358 Super Ram made 392whp with dual cats, SLP Headers, 280xfi cam, extrude honed Big Mouth TPIS manifold and Trickflow 195 heads, 1.6 roller rockers and hooker 3in cat-back. All emissions hooked up.
Thank you for doing this test! There isn't enough 350 tpi tech around. The results you got would make a great street machine. Would love to see some real world vortec headed TPI tests for us guys who want to maintain the integrity of these cars. I feel like they may be coming back into their own.
Agreed! I bought an old c4 to learn how to work on cars, but totally neglected the lack of info on cars from that era since they are overlooked because of other more desirable generations. I just want 500 hp 500torque out of it. Just hard to figure out where to start since the corvette forums are full of old men who bitch about any questions related to going beyond stock power specs or all the build info are on the later gen c4’s and I have an 85 with the weaker engine but forge pistons from the leftover higher trim models from the c3😂 I need an engine rebuild so might as well give her some extra umph 🎉
@@jakejake7162the corvette guys are the worst. I don’t even consider them car guys it might as well be an investment forum. 500 horsepower and 500 pound feet isn’t something that can be done easily and honestly I’d say if you could knock down 20 numbers from either the power or torque it would be more realistic since these motors only have so many induction systems that make disproportionate power and torque. There really isn’t an intake that will make that power with a stock block unless it’s a built fire breathing 383 with a performer rpm and all forged bottom end. I’m a budget guy so it dont even consider it in my world of expertise lol
@@jakejake7162 You're not getting 500 hp and 500 ft lbs out of a TPI 350 running pump gas, naturally aspirated. Buy a DART SHP 406 SBC short block, and put some top-shelf 195cc - 210c heads on it, the FIRST fuel injection TPI-style intake, and an AGGRESSIVE roller cam and Holley Terminator to control it and 500 hp / 500 ft lbs on pump gas is EASY. There's no cheap big power with TPI; you CAN make shockingly big power with them vs. what most people think, but it's going to COST YOU. (I've got a decently budget 440 HP SBC 350 FIRST TPI-based build (if you ignore the cost of the Holley HP EFI system), but I bought all the parts 6 years ago and took my sweet time.)
@@jakejake7162 Build a 421 out of a factory 400 block, use AFR 210 heads, or have a set of Profiler heads ported for even more power. (210 heads). You'll be over 500 hp and torque.
Not a fail. The tests prove that a stroker kit is the way to get 500 pound feet from a TPI small block. 465 torque from a 350 is no slouch. It did just what you taught us about TPI motors way back in the day - massive torque. A Comp XFI cam might have made a little more, but building a TPI stroker is the real answer!
465 foot pounds out of a 350 would have been ludicrous in the 70’s and 80’s. Everyone was running torker ii’s and making like 360 foot pounds and the same power number as this motor. I thought my 350 was a torque monster for making 420 foot pounds from a mild roller cam eps intake and world s/r torquer heads. Low end for days and pushed around a heavy square body like a big block.
Throwing in a cam with 107 LCA and 35-40° of overlap will get the right cam needed for maximizing torque which should be around 490 ft-lbs and be 1.4 ft-lbs/CID.
Mill the heads for a bit higher compression. Tune primary length on the 1.75" headers. Tune collector length as well. Add 1.7 roller rockers to take better advantage of the head flow. Scorpion makes them for sbc. I'm running them in my daily driver on my old 92 c1500. Larger throttle body if possible.
I guess youve never heard of port saturation or parasitic stress on the crank. You guy and this massive lift, in most cases high lift loses horsepower. Theres a point (especially with stock heads) where they start to lose power because the ports dont have the ability to flow any better. The stress the added lift puts on the crank due to increasing spring pressure cost horsepower. You use the lift that the heads are capable of flowing and valve springs that dont cause the crank to work harder to turn. Most small block street engines like .450 - .500 lift and 325 - 350 lbs of spring pressure at max lift. Going beyond that does little if anything as far as power is concerned.
106 LSA and 11.5 to 1 compression will get you there. My only issue is that we're limited on airflow with the Tuned Port Injection set up. Also I'm wondering about installing collector extensions with mufflers. You never know until you try. I hope you return to try again. Nice work Richard. Thanks for doing all these test
106 LSA and 11.5:1 is helpful, but it'll knock like crazy on pump gas. Top shelf heads + the FIRST fuel injection TPI-style intake and an aggressive roller cam get rid of the airflow issues, withing the RPM window that you have to work with with the long runners. Long runner engines pushing the boundaries quickly become octane limited. Great quench velocity, cold coolant and cold air help to a certain degree, advanced fuel injection strategies like open valve injection can help a bit more, but if you want to REALLY push a TPI engine, you give it compression and E85. These things cry out for E85. (Get you more oxygen and more knock resistance.) An E85 all-out FIRST TPI build would be so awesome...
XFI hydraulic roller cam up to 230 or 240* duration with extreme ramp rates that match larger diameter lifter rollers. Extra high lift. 7MM or 8MM valve stems. 1.7 high average ratio roller rockers. PAC Beehive or other conical high quality springs. 106* LSA. 2.2" intake valve. 1.5" exhaust valve. High attention to detail on AFR 210cc heads or Promaxx Project X215cc heads. Enough swilr and tumble blend with 300 fps velocities in high port energy and efficiency head. A giant single barrel carburetor with a part throttle circuit modification like the Pro 1 single blade carburetor on a dual plane or dual cross ram divided ram intake manifold. Very high cylinder pressure with proper fuel enrichment jetting for WOT. Then with best results slightly enhance results and make a short stroker between 358 and 372 cubic inches. I.E. = 3.5" crank, 3.625 to 3.64 or 3.65" stroke. The 3.5" stroke could net you a 10 ft lb increase. Or a 3.6" stroke would be really nice. Part of the reason the 383 stroker does so well is not only the additional cubic inches. It's bore to stroke ratio is perfectly in the zone of efficiency. So if the stroke and bore was reversed it would be equally in the perfect zone as well.
I think no on the 4/7 or the 4 pattern and you will be hard pressed to find a better head than the AFR, the tighter lsa will work, no on changing the bore/stroke (displacement makes torque)
I like where you're going here. Totally agree on the XFI lobes, but still on a tight LSA and all the extra valve train stuff to control those lobes and more rocker ratio. You're kind of "changing the game" with changing the intake, though. I think the challenge of the limitations of long runner intakes is what "makes it fun". If you're stuck with the long-runner intake; then a FIRST Fuel Injection super high flowing TPI is a part of the recipe, and I think you want MORE STROKE because you're RPM limited and the extra piston FPS is useful; it also helps provide more quench action to fight the detonation that becomes a risk as you push the DCR of a high performance TPI engine. -Combine the extra stroke with thin piston ring packs to not lose some of the torque from friction (the 1mm ring pack Mahle PowerPak pistons are perfect and reasonably priced). You COULD do fuel enrichment to fight detonation even with EFI and keeping a long-runner intake, but with a modern EFI system you can also use an Open Valve Injection strategy that helps reduce detonation risk, too.
Best truck intake that never was. Had one in an Iroc-Z and the part throttle drivability and response is something I haven't experienced in anything else. Small cam, Brodix street heads and 1 5/8 headers is a potent little combo.
What do you think are good 4wd transmission options for a tpi setup like this? I wanna rip mine out of my vette and throw it in a 2 door wrangler, then figure out something a bit more ballsy for the vette 😁
More compression always helps. David has said the 383 is geometrically superior than the 350 because it gains more power than the displacement predicts. This test shows similar.
Yep. The TPI engines are going to have a lower RPM HP peak, so increasing the stroke is super helpful with them as it gets the average piston speeds up AND it gets the quench velocity up which helps reduce detonation risk on these things. A 4"/4.030" bore SBC 396 would be great for a high power TPI build. (Thin piston ring packs become more useful with the higher piston velocities, too.)
I agree, tighter lsa and more lift. Usually can get away with lower duration and more lift with roller camshafts. Remember higher ratio rockers add more valve lift everywhere not just peak and thats what adds torque. I love the tpi for truck applications. Currently have a 383 tpi with lt4 hotcam with gt45 turbo.
Occasionally I would see a C4 or an IROC (auto) scoot down the 1/4 mile much better than stock. Besting the LT1 even. And under the hood it looked stock, no power adder. I was thinking stroker and porting. Back in the day.
Hi Richard, I think the first cam you used with a tighter LSA might’ve helped up the torque. Something we learned in your other video and coincides with what David vizard talks about in his books and videos. Thanks for always producing excellent videos!!!!
Yes, they did the same thing with LSA on Engine Masters (quite?) a few episodes back. Mentioned tightening up the LSA of an oval track car for better "pull" out of the turn.
HEY RICHARD. More aggressive cam lobes... Howard's has a lobe that specs 281 duration 231 at .050 .552lift .589 w a 1.6. Have it ground on a 108 lsa. I have a hunch that tpi engines will respond well to a mild single pattern cam with lots of lift on a tight lsa.
@@b.c4066 I'm running the Mike Jones 70375 / 71360 on a 110 LSA in my 350 FIRST TPI build, so I have to agree. ;-) 272/280 ADV, 227/228 @.050", .600"/.576" with 1.6 rockers. Mike said if i didn't need vacuum brakes, he would've gone a little bit tighter still on the LSA, too...
Aloha from Maui! I have a 90 corvette as my daily driver and I'm saving up to have the motor torn down and rebuilt. As of right now, it has cat delete, x-pipe and 2 aftermarket mufflers. I would love to have my car make some beautiful music out the pipes and more low end torque for light to light, have a little fun and really don't need top end speed due to living on a small island. With it as my daily, I am thinking of having it bored 30 over to a 355 instead of a 383 to keep the structurability and from wrecking the engine later down the road, short tube headers, x-pipe and straight pipes all the way. I've been told that I can keep the original TPI and get up to 400hp and 500 fp torque and those are the numbers that i would really like to see. Recently I talked to a buddy and he said to slap a charger under the hood and I should be able to see those numbers, but I may run into problems with tuning with the old computer tech from the era. What say you?
I have been wrenching on tuned port engines since the first one rolled off the truck at the dealership I was working at in ‘85. I have tried lots of combinations with both good and bad results. But honestly, the best I have seen on a 350 TPI is in the 450 ft lb range. A TPI engine is kind of limited to that sweet rpm range. I enjoy torque in a streetcar so it works for me. Your Y-pipe results are interesting because an X-pipe seems to help mid-range torque with a slight loss at lower rpms. My current tuned port has absolutely as much material removed from the inside of the plenum as possible because the stock plenum volume is too small with this design. In fact, it’s still too small after mods. I think that a 383 is probably a better choice if 500 ft lbs is the goal. I have a desktop Dyno sheet stashed away for a virtual 383 TPI that pulled a hypothetical 550 ft lbs. If driving something like that doesn’t put a smile on your face, someone should check you for a pulse.
Yeah it may just come down to the lack of rotating mass at the certain rpm the tpi likes to spin at. The 383 had always been a disproportionately powerful motor that makes uncharacteristic torque for a small block but still capable of high rpm power when built for it. There might just not he enough stroke and rotating mass to take advantage of the tpi’s strengths. As a matter of face there’s a video floating around with a 305 stroked with a 3.75 inch crank to make a 334 and a tpi setup and made some tuning crazy like 430-440 foot pounds. That big crank is the thing that turns the tpi into its own in my opinion but it’s all conjecture so what do I know lol
@@theeoddments960 , My problem with a 305 is that the small bore seems to shroud the valves and reduces airflow substantially. So there seems to be a limit on how much power you can make aside from just the displacement. I ran a 383 with a Holley 3310 in the 90s and loved it. And I swore by stroke for many years as being the key to torque. But Dyno numbers suggest that it is more about displacement. These days, I believe that aftermarket cylinder heads would give a 377 an advantage over a 383 due to it’s larger bore and better flow potential. It would just breathe better.
@@richardholdener1727 465 ft Lbs? One of my favorite 350 Mag engines did that with an oriental Dual Plane. "Budget Sledgehammer" Sept 22, 2006 Dulcich/Hunkins.. L31 block w iron EQ Vortecs, 10:1 comp w shaved heads/58cc chambers. They used a Vizard spec 224/224 108 LSA cam with 528/563 lift w 1.6 rockers (Comp Cams custom).. You've got better heads than they had, you've got a better manifold for torque than they had .. Use their cam. The mainstays of torque are stroke, size, compression, camshaft .. My armchair suggestion .. Similar spec cam .. maybe up lift to .550 minimum, 11:1 compression with Flatops only- no domes (there are factory sportbikes with this ratio it can be done) max cubes on 350 archetecture.040 over gives you 359 ci .. .060 gives you 362 ci .. 10% of 400 cid is 40 cid.. So a 360 cid engine is 90% of a 400... 90% of a 400 means you'll hit 400 level air demand just a few RPM's higher in the scale. This is a great concept Richard .. 500ft lbs/350.. the power/torque from the 383 w TPIS or Extrude Hone Tune Port manifold was insane .. Inspiring. The factory spec on the 1970 Chevelle LS6 454 was 460hp and 500 tq @ 3600 rpm with 11:1 comp.
Memories... I ran that 218/224 cam in my IROC. (CIRCA late 90s) I think mine was on a 112 or 114 LSA though, maybe I'm wrong? It was another lifetime ago. I had a stock 87 L98 shortblock, that cam, a set of 2nd hand heads off of a ZZ4. It ran well for what it was.
What heads in particular are those? Most AFR heads continue to see improved flow all the way out to 0.600" lift The duration is probably about right for the goals here, but there is the possibility that 20-30CFM was being left on the table by sticking with the low lift cam.
Perhaps a little overkill but... everyone always does the 383.. I know it's a little extra effort but what about a 396 stroker, fully ported and port matched tpi intake to AFR 195's, not sure what cc chambers would be the best, 65 or 75.., tpis large tube runners, fully ported plenum, comp xfi 268 cam. 218/224, 113 lsa, 568/572 lift maybe, pick a throttle body, whatever you think is best. We all know a stock 48mm can support 500hp. Maybe 24# injectors and one hell of a custom burned ECU chip. If torque is the name of the game then there's no replacement for displacement. This combination could belt out around 480hp and 550tq if my calculations are correct. Now that would be a "bulletproof" street motor. What do you think? Can it be done or am i completely wrong lol. Thanks for all the great videos and content!
@@richardholdener1727 by"calculations" I think I meant more like speculations. Was I in the ball park tho at least? Solid combination tho? And thank you for responding sir, i appreciate the feedback.
Im sad that i missed this when you posted it, as I feel a direct correlation to my 500ftlb comment in my L98 on a previous video inwhich you said "a tall order". Pretty damn close, and like i said mine is 470ish. Inwhich I rounded... what man doesnt stretch a bit 😅. Great vid. Thanks for verifying.
I think your answer is in the early video, you made the area inside the pipes larger without changing the length, and made more everywhere. Probably could use some small exhaust pipe elbows to add even larger volume. Outside of that, I think I'd try to crank up the fuel pressure and some 4 hole injectors, and give it all the timing I could, regardless of how rich I had to run it. I don't know how you'd use an h pipe on a dyno, but using one side of the exhaust to pull on the other might be worth a shot.
Custom cams are expensive: 224/232 @.050, 106 lobe separation, installed @ 102 icl. Cranking compression should be 190-200 for pump gas to work. Just guessing I hope it works. Try this combo with 750 carburetor also 😊
My guess would be deck the block and/or heads for more compression, notch the bores of the block to unshroud the valves, a bigger valve package, and possibly a tighter LSA for dynamic compression. My position is allow more intake charge in and compress it more.
So sad that I missed this one for 6 months. GREAT set of tests! As you know increasing torque per cubic inch is HAAAARD. To hit 500 ft lbs, you'd have to make 1.41 ft lbs / cubic inch on a 355, which is a difficult feat without a big budget. The easy way to hit 500 ft lbs on a 350 inch TPI SBC: Use highly oxygenated race gas; something like CHP+ circle track gas, or E85. Combine that E85 with a bunch more compression and it gets even easier. A more aggressively lobed cam would help; obviously you have to keep the seat-to-seat durations in the range that are going to work for those long intake runners, so the big option to increase VE at the torque peak is to get more lift with the same seat-to-seat durations. -Higher ratio rockers -yes, moving to a more aggressive hyd roller family like the XFI lobes (but on a custom tighter LSA), or moving to a "street Solid roller". Compression is obviously useful but pump gas and high compression and high VE is a combination for knock in a real car when you don't have 160F or colder dyno water. Meth injection would help, but so would using an advanced EFI system like Holley HP or Terminator and using a strategy like "Open Valve Injection" and significantly larger injectors that can inject all of the fuel when the valve is open in a small number of degrees / milliseconds: you get more evaporative cooling with this strategy right before the intake valve closes and it allows you to use more compression with the same octane fuel. (Bosch found that they can run with +0.5- +1 CR increase in static compression with the same octane fuel when using an open valve injection strategy.) I've seen SO many tests of TRI-Y headers now where the TRI-Ys lead to over-scavenging and then a torque drop for part of the curve; that's my suspicion on the TRI-Y test; open valve injection is also ideal in this situation, too, because it can be timed so that injection doesn't start until overlap is over, at least in the low to mid RPM range; then you're not just shooting the fuel out the exhaust during overlap and seeing that torque dip. Reducing friction where possible can help make tiny gains, too; those Mahle Powerpak SBC pistons with the 1mm ring pack option are a great option to help maximize CR and reduce friction at the same time.
Just curious for the below average guy like me! How does Vizards cam formula work out with factory heads or even the best aftermarket heads & stock bottom? Can the factory cam be optimized for the stock setup?????? I'd love to come up with the BEST top end package & intake including a custom cam at all costs, but for the below average guy who doesn't want to pull the motor, or have yet to find anyone in S. Florida competent or honest enough to do a full built 383 ect..... At one point I wanted to put on a supercharger kit & intercooler......so the C4 with 19k miles stayed in storage for many years, due to health problems. I'm planning soon to carefully get it running & pre-lube the engine with a pre-oiler ect, ect. before even turning by hand. Glad I drained the tank, but not fuel rails, but ill put in upgraded Bosch 22lb EV 1.3 vs. the troublesome Multecs. My biggest fear is rodent damage since the storage facility once had major rodent problems, so first on the list is 20 traps & Jug of Skippy & Jam .🐁🐁🐁🐁🐁🐁😏 If I find the worst, ill just throw in a loaf bread & let them make their own sandwiches in the front seat & just give up on my dream.🙄
Try a Comp Cams 268h and 1.6 rockers. Back in the day I had a stump puller of a '76 BLAZER with a 383 that cam, flat tops 10-1, 650 double pumper, and an Edelbrock Torker manifold. I know, 383 and Torker are different, but the 268H and 1.6 rockers are solid. I would be curious to see what they would do for you. It was an amazing combo for me! I used Rhodes lifters, remember those???
Ran a 355 tpi at 10.25:1 w/mildly ported iron eagle 180s, lt4 hot cam kit(so 218°/228° .525" on a 113lsa) and the old edelbrock tes headers for a few years before stepping up to a 385 stealth ram setup. My assometer is not certified but 450ish ft/lb sounds abt right. 1st gear with a 700r4 was wonderfully useless
It's incredibly scary to disagree with Richard and his dyno time, but I'm going to 100% disagree on this point and say "yes". 1. These TPI engines are usually oxygen-limited and E85 brings with it plenty of extra oxygen (like an oxygenated race fuel). 2. When you have a real street-driven, high performance TPI engine and you're pushing the dynamic compression to make max power, the big VE can cause detonation around the torque peak RPM in a real car with 200F engine coolant and if you have to pull ignition timing to avoid the knock, you're leaving power on the table. E85 allows you to push the dynamic compression in a high HP / Torque TPI combo without needing to worry about knock, so you can keep all the timing in that it wants. (If you use E85 to push the compression higher, "Certainly Yes".) The general consensus on these comments seems to be to add more LIFT, go with a tighter cam LSA, add more COMPRESSION to hit 500 ft lbs from a TPI 350. If you go in all three of those directions, the E85 becomes particularly useful, because all three of those things will bring you closer to the detonation limits of your fuel in a real car with real world (not 150F cold dyno water) coolant and air temps.
I'd try adjusting the cam timing. Pull the plugs and set up a compression tester. Test as is then start moving it forward and back until you get the highest compression reading. Then retest. I have feeling you will find more torque at a loss of hp.
From the pic you showed of the Tri-Y header it is basically a shortie header design with pairs of primary pipes connecting at 270* and 450* degrees of crank rotation, which i think usually favors higher RPM operation, and not ideal for the TPI engine. I would have tried to find actual long tube tri-Y headers with the pairs of primary pipes connecting at 180* and 360* degrees of crank rotation, like the tri-Y header version that works so well on the chevy big block, made by a company called Schumacher. I think use of this type tri-Y could help the torque peak. Boosting lower RPM torque is not the easiest thing to do for an engine builder, and you'd usually use things like more mechanical compression and tightening up the LSA on the cam, but other than swapping cams you might just advance the cam about 6* degrees and put a higher ratio rocker on the intake side to see if that might boost up that peak area and get your desired number. Personally, I think that a compression ratio of at least 11.5 would be in order for this type engine especially after you added the larger cam. Inside the TPI plenum you can sharpen up the divider between the ports that feed cylinders 5 & 7 and add more radius on the forward side of the #5 port to cut down on the charge stealing, and this will boost up the lower RPM torque a little. I hope to see you try this test again and get your number. Dan Olympiadis.
All tests are learning opportunities. I think 1 5/8" is just too small at 355 inches. Could use a balance tube as well. Increase rockers test1.6, 1.65, 1.7 for sure. Most of us would rather do a fast rocker swap than a long cam swap. Good video.
"1 5/8 is just too small at 355 inches" The late Jack Davis (formerly at Hooker back in the day) would build headers for the 454 powered crew cab dually tow rigs of his and friends drag cars. With 1-1/2" primary tubes about 42" long into 2-1/2" collectors. Pass others on the Grapevine, and at the gas pump.
OK, same small cam but on a 108*, another point of compression , and E30 for fuel (or E85 if that's easier, or equals better availability). I would have used the AFR 180 heads too!
Thanks for sharing! Very well done. Valve timing was all spot on, but I think the big cam told the story. The bigger tubes needed more duration to get the gain in tq. The smaller cam probably would have done better tq yet with the smaller tubes. Pressure wave tuning is completely different than everything upstream of the throttle body, diameter and length both affect Helmholtz resonance.
I think that the crankshaft stroke length has the biggest and most direct impact on torque production. None of the cool stuff you applied during the tests can increase the stroke length, only changing a crankshaft can do that. But I have no idea if putting in a crankshaft with greater throws/offset is even an option with that engine. Cylinder diameter and cylinder wall length, connecting rod geometry, and piston geometry and piston skirt length may already be optimized or maximized for that engine. Of course, may be missing it as well. These are just some thoughts that I thought would be worth sharing. Thanks for another great video. Take care
For the same volume there's no difference between stroke or bore, unless it's flow limited and you need the valve size that's possible with bigger bore.
Love the L98 videos. I have an 85 Corvette, and have a TPIS Miniram, Comp Cams 280xfi and AFR195 Comp eliminators sitting on the shelf ready to bolt onto the stock bottom end. Probably a bad idea but I want to give it a shot. I'll just have to set a conservative rpm limit until I have a real shortblock to back it up.
Hard to wrap my head around… this exact same combo with a little hotter cam and 3.750” stroke went from 372hp to 450hp. That’s nearly 70hp with just .252” more stroke? I would’ve figured a ported TPI intake with bigger runners would at least make 400 with AFR 195’s and a cam.
Richard, I think you can get to 500 lb/ft, but it's gonna require 11.5:1 compression and 1.65 rockers on the intake side.....a cam with 108 LCA would be ideal but I think you can still hit the mark with the cam that's in there..........just my thinking on it
Just discovered this video! Can't wait to watch the 383 video! How about 1.6 rockers on the intake side with a single pattern camshaft. Better yet a camshaft with more lift on the intake side like the mutha thumper line and what you have already mentioned, tighter lobe separation 106. I don't understand and it was never made clear, why the 1.39 ft/lb per cube formula not only didn't work but was off so much. Thank you for the great video. I'm building a 10.6 to 406 with AFR enforcer 195 heads, .450/.450 218@.050 106 flat tappet hydraulic cam with 1.6 X 1.5 roller rockers and performer eps intake. I am using lightweight rods and lightweight wristpins (156 grams vs. 92 grams) I wonder what kind of power I should expect. I'm guessing 375 hp @ 5100 rpm and 515 lb/ft torque @ 3800 rpm!😀 for my '64 Biscayne with a th350, 2,800 stall and 3.36 gears
This is why I'm building my autocross engine with a LS truck manifold and really long tube headers, and a long duration cam with a tight LSA so it will keep pulling past peak HP without losing too much power. Autocross doesn't need lots of HP at high RPM because the car is not going fast enough to be making much drag so it will still accelerate past peak power if the power doesn't drop too much, and that big cam 383 with the TPI intake only lost 3 HP between peak power and redline. I'm hoping my engine has a similar power curve with the TrailblazerSS manifold and really long tube headers and the Jeg's 295/336 cam.
Richard, how about a dyno test on a dual plane manifold which has had injectors fitted close to the head ports MPI style. Then dyno test it against the same manifold running a carb. The purpose is to see what happens with the Air/fuel ratio in each cylinder. Will the EFI cause rich/lean cylinders due to uneven air flow but equal fuel application to each cylinder. Especially at low RPM's. Typical manifold would be a Edelbrock RPM air gap.
if you have port injection, you can tune individual cylinder to optimize the af at every rpm (see the video I did on this using the single plane) It will work the same with a dual plane
If I remember correctly, First recommends 224 duration around a 112 LSA. It be interesting to see what a tighter LSA would with the 224 duration. Keep up the good work!!!
It depends if you're keeping the stock ECM or not. Aftermarket EFI will support tighter LSAs and more overlap. You go with a more aggressively lobed cam, you can keep the tuning and the seat-to-seat durations where they need to be and the @ 0.050" durations and lift numbers get bigger, too. Modern EFI gives you a lot more options on these high power TPI builds.
I ran TPI on a G20 van. At low rpm off-idle to 2,500 rpm, it sucks compared to TBI on a dual plane. The TPI only made more torque than the dual plane with TBI from about 2,700-3,800.
@@chrisreynolds6520 People don't talk about that ENOUGH! TPI are great a MID RANGE, but at RPMS above and below the tuned range, those waves arrive at exactly the WRONG TIME and make a torque dip. (The real reason for TRI-Y headers: to attenuate those waves, so that the AVERAGE power across the RPM band goes up vs. having the big dip on either side of the tuned range.)
In my opinion, it's the stroke that helps produce all that low speed torque . It's difficult to make up for that. It would be interested to see what another point or so of static compression would do. Let's cut to the chase and add some boost.
I think more lift to take advantage of those heads, and a tighter LSA. Not sure if primary diameter or length would get it there. Aren't unequal length primaries for best scavenging in need of development?
I agree with you. More lift and more compression and then increasing Ethanol gives you the added knock resistance AND more oxygen stuffed into the cylinders.
It has probably been said but tighter LSA on something like the smaller cam (so about 106 lobe separation) and advancing it so it would close the intake sooner and shift torque to lower speeds, like 100 to 102 intake centerline, but along with more octane so timing could be advanced more and/or more compression and timing and octane may have done it. I thought you had testing a F.I.R.S.T. TPI set up but I don't see it....
Some comp xfi hyd roller lobes, around 216/216 on a 105 lsa, 1.6 rockers, and another point of compression. Peak HP might not impress, but should do the trick for making a big peak torque number in the 3500-4000 range
I knew it! I didn't trust those triple Y headers to be better than long 4:1 headers, seeing it well is almost the same 🤷🏽♂️. To increase power a solid roller camshaft with more lift and duration will help a lot
I had a completely stock 1963 Impala SS with a 327/Glide combo that had Horsepower Engineering Tri-Y headers on it since it was new. In the mid 70's the headers were rusty and leaky, so I had it on the rack at work so a buddy could weld up the leaks. Fired it up, sounded great, start to back out of the shop...and the rack wasn't all the way down, and tore the hell out of the headers. Had to replace them with some Hedman 4 tubes to get back on the road. It felt like I had pulled 2 plug wires off! It was a gutless turd with no bottom end at all! Gas mileage went down, driveability sucked, I couldn't believe the difference.
I agree completely. People don't talk enough about the benefits of a Solid Roller cam on a long-runner build! (I disagree on the Tri-y comments, but that's a much longer conversation.)
On the 383, can we talk about how the Performer RPM made 100 hp more than the stock TPI? Seems like the way to go. Give up some low speed tq, in order to gain 100 hp. Cheaper, simpler, too.
Would be fun to do a setup with 2n or 4 used VW 1.9 - 2.0 TDI turbos on a motor like this just to se how early the boost comes on. Or just 4 really small turbos on any SBC/BBC.... You get those new for like 220$/piece here on the other side of the pond, but used is what is interesting since you almost get them free if they are close to end of life. A tiny budget "other guys" video, excluding engine management cost (there has to be a clever and cheap way of doing that with far eastern stuff?) would be so cool.
I like the idea of trying this again with testing cams that have a little tighter lsa. Also how about header collector extensions? Those seem to often help. Are zero-gap rings a thing? There were magazine articles about their benefits in power production back in the late 90s. Maybe one of those articles was authored by you?
Try the thumpr cam with 1.6 ratio on the intake. the tighter lsa and the extra lift on the intake will take advantage of the long exhaust duration and extra scavenging.
Are the heads as-cast (not ported or cnc at all)? I believe a good smaller port in the 170 range, a stock hand-ported base, stock runners blended/raidused at the plenum (opening the plenum like you would to siamese a pair of runners), and a custom cam you'd hit your number... might even make more power too! I want to say the short primary section of the tri-y setup is what hurt low end torque. I don't know enough science about it yet, but I have no reason to NOT believe the long primary size of the regular longtubes don't offer the same benefit to low-end torque like TPI does.
Here goes. 13:1 compression, 1mm rings, 2.05/1.72 valves with 30 degree seats, a solid flat-tappet cam with 220/236 @.050 and .525 lift with 1.6 rockers and 108 LSA installed 6 degrees advanced..and a bag of ice on the plenum.
I would have tried a 106 or 107 LSA cam. A little more compression and 1.6:1 rockers would have helped too. One of the magazines ran a Vortec TPI with a SDPC lower intake and got like 489 ft lbs of torque on a 355 SBC, so a little more playing around and you could get there. You might want to talk to David Vizard and ask how to eak out those last few ft lbs. I would love to see how a TPI power curve looks on a mild 400 SBC. Torque, torque, torque! That would be a killer truck set up!
With 130° coolant temperature, 190° oil temperature, no water pump, no intake filter, no alternator, and open wheel modified headers that will never fit in a street car chassis and maxed out timing they got that. What those kind of tests do not show you is.. run it in that state for 1-2 minutes at normal operating temp and it will die. Take magazine article tests with a grain of salt. They are paid for advertising parts, high power numbers sell parts. If all you want is a trailer queen for the track sure! But who builds a track only car then strangles it with tpi? Build a 383/400 use a well ported first performance tpi with afr 195 comp eliminators, 10.5:1 compression and around 280/280 advertised, 228 to 232 @ 50 with as close to .600/.600 lift as you can get, keep quench tight (.035-.039") and it will make 500+ foot pounds, 435-465 HP. Make sure the piston crowns and combustion chambers have been softened, no sharp edges, use a decent 1-3/4" primary around 30-34" long, 3" collectors, full 3" dual exhaust with good dynomax super turbo mufflers and at least a 2500 rpm stall converter with a well built 4l60e. It will make close to 350-375 rwhp, 400-440 rwtq if you build the drivetrain right, in a 3200 pound car it's a super simple easy low 12 second car that can actually be used and driven daily without cam surge, overheating, or destroying the valve springs every 10,000 miles. Not cheap, now days simpler to just get a 6.0/6.3 LS with mild cam and springs.
Try the stock runnters. Your ported runners are meant to overcome restrictions at higher RPMs. The factory TPI was designed for low end torque. Limit lobe overlap. more overlap results in lower real world compression, less torque. Not even sure the 500 lb-ft is the right measure. Torque is best felt at lower RPM applications. You don't "Launch off the line" in streat applications at 4000RPM. You need to maximize torque at 2000RPM to have a great streat car.
@@richardholdener1727 Less HP is fine on a street car if it is sacrificed for a flat torque curve that starts no later than 2000 RPM and gets over 400ft/lbs by 3000. However, I realize now you are just making entertainment, not doing anything practical or helpful. I Got a hint with that with your destroker/stroker vid where you changed so many variables your results were meaningless. Time to quit wasting my time. Adios.
500 lb/ft divided by 350 CID = 1.43 It is said that only the top 10% of engine builders can manage building 1.35 lb/ft/CID engines and only the top 1% can manage 1.40 lb/ft/CID. NA engines of course.
@@richardholdener1727 It definitely is. Maybe to lofty. Not impossible but close for most of us because a SBC with 3.75 " stroke is more efficient than all the ones with less stroke. I believe one need "high" pistonspeed, "high" airspeed , "high" valvespeed and 108 LSA camshaft with 224 +/-2 degrees intake duration at 0.050. Speier ported heads on a stroked 307 CID engine. ;) :D
I built a 355 then 383 in 1989 and used a cam dynamics 306 enforcer on both engines with a 106 lca. I have to say i couldnt believe the torque from that cam. No dyno results but seat of the pants. Lol.
I think the tri-y headers were not the best example of what a good set of tri-y headers could do. Increase the primary lengths to that of a good set of long tube 4-1s reduce the secondary y to 18 inches and run a good 3 or 3.5 collectors look at NASCAR or V8 supercar headers. Oh and the answer is always boost gt45 cheap China turbo or a good China Gt3582RS something like a PSR or a factory Garrett from a xr6 turbo
I think the tri y headers only work better with the ford firing order. BMW, Merceds have also offered tri y exhaust from factory, but they all share the firing order with the late model ford.
@@danr9584 yes and no Honda's seam to respond to tri ys better than 4-1. The issue is it's very easy to get any set of 4-1 headers to work while a good set off tri ys takes alot of math but even more testing as the range at which they really work will be different for each engine combo. I will definitely agree Ford's are easier to get to work saying that I tried 4 different brands of tri ys on a 4v 5.4 before working out what primary and secondary dimensions worked best throughout the entire rpm. I still maintain that well designed tri-ys will out perform 4-1s look at motorsports very few V8 American/Australian racing cars that run 4-1s (again talking about the big league ppl NASCAR etc)
The problem is 11.25:1 with the high VE at a torque peak between 3,500-4,500 RPM makes it a knock-monster in a long-runner build. You have to run the cam in the range that it's going to make power, and then you get skyrocketing VE on these long-runner builds at that torque peak and you get knock even on 93 octane pump gas with cool coolant and a cold air intake and you have to pull timing around the torque peak and the power per cubic inch goes back down from having to pull timing to run on 93 octane (On the WestTech dyno with the water set at 150F, it might be ok, but in a real car... It's a problem.) A good long-runner TPI build on 93 octane makes it tough to avoid knock even at around 10:1. -I agree with you completely on the approach, but then these engines become knock-limited (they cry out for E85)...
Imo I’d run a tight LSA and adj the duration for a decent idle quality.Unfortunately people do the opposite when they try to get a decent idle quantity.
My first change would be a pair of Extrude Honed Dart 200cc cast iron heads so the engine would keep compression that aluminum heads would lose. 2.05/1.60 valve package, a roller cam with a .050 duration of 218°int and 230°exh, .520 lift int and .535 lift exh, and a 112 LSA. And instead of a 355, I would go with a 4.125 bore block to unshroud the valves and have a 372. Keep the same TPI combo from the original test. Flat top pistons, with a modern ring package and dual valve reliefs. 1 3/4" diameter, long tube headers into a pair of Flowmaster 4-2-1 collectors and a 3" X pipe. See what happens.
11.1 compression, more lift with a good Roller rocker use cam with tighter lsa. A switch to a 180 cc head from arf may help, for torque you def want to maximize the velocity of the head. I am going to be using a 170 cc edelbrock head that will come out to a 18ish cc head and will flow around 270 at max but have killer 250 numbers in midrange. Add some good engine oil maybe a windage tray with baffle and crank scraper. If that gets you close add a first tpi and then have that manifold worked, i think it could be done, my combination will be similar but with all the things ive said, i calculated 500 ftlbs minimum at about 4k and 420 ish hp at 5200 to 5500 or so....will shift that at 6k and hope for mid 11s in my camaro.
Look at the FLOW for the cross-sectional area between the 180cc AFR head and the 195cc AFR head. The 195cc is the velocity "sweet-spot". Velocity is determined by the amount of FLOW per the cross-sectional area; it's counter intuitive, but you CAN have a bigger port that has more velocity than a smaller port.
Larger tri-y's with an ordered 8-4-2-1 configuration will flatten the torque curve; not make "more" peak torque. Of course, it's gotta be dialed in, not just bolted on. Otherwise, when all else fails: just get the burnt air OUT as fast as possible (4-1 large and long tubes with good collectors).
Haha. OK, shoulda run a smaller cam in the 383 as you said, but the 383 did pull a bloody good torque number with that biggish cam. @@richardholdener1727
Thanks Richard! All very informative. I have 4x tpi sbcs in C4 Corvettes. 2x383s, 2x350s, 2 have Super Rams, 1 has an old Paxton SC...How about building a 350ci TPI from a 305 block with a 4" stroke? If you can get a good flowing head on the smaller bore, I'm guessing you'll get 500ft/lb with 4 inches of stroke.
@@richardholdener1727 To gain torque you could have used an old Header by Ed catalog advice, and cut up the 4 into 1 header and ran the set up into a 4-1 collector. If done right, you coulc have flattened out the torque curve some more.
Have You tried L98 350 (355) with higher lift? Lingenfelter made camshaft with 0,560/0,560 inch lift to use with Superram intake. That cam is short in duration 219/219@0,50. As an alternative I like also Comp cam XFI 218/224 cam with 0,57/0,565 lift. I am trying to choose which of these to cams to buy for my SBC 350 89' Corvette. It has Superram, ported 113 heads, forged pistons and oldschool Paxton supercharger, Crover Enduro roller rockers 1.6/1.5, tri y headers.
These tests always make me feel conflicted, I have an old TPI engine that is due for a refresh and I think I should hop up, but in the end I know if my goal is easy power I can get it out of a 6.0 LS so easily. If Super Ram intakes hadn't become so silly expensive I'd probably run one of those on top of a 383 just for the nostalgia factor.
Stick to sbc....!!!! Represent!!! Torque is king!!!!! I had 355 that would leave an eleven marks doing 55 to 60 on the highway!!!!!! 🥺😢 I miss my 90 silverado!!!!!!
I'd love to stick with the SBC and tpi and keep my car "period correct", but as you said, LS power is just so damn easy. And unfortunately all those good old intakes are prohibitively expensive for me.
About 10.2:1 compression, heads with smaller cc intake runners with 1.94, 1.6 valves, higher lift camshaft with 107° ish lsa, high flowing 4 into 1 long tube headers would be my thoughts
358 Super Ram made 392whp with dual cats, SLP Headers, 280xfi cam, extrude honed Big Mouth TPIS manifold and Trickflow 195 heads, 1.6 roller rockers and hooker 3in cat-back. All emissions hooked up.
right
Your car is 3rd Gen infamous! Dynoed at Dyno Dons, MAAANY times, right? SuperRAM is cheating in a "true long runner" test, though. ;-)
@@adamarndt7617 Right! Have you seen the rest of the videos?
Thank you for doing this test! There isn't enough 350 tpi tech around. The results you got would make a great street machine. Would love to see some real world vortec headed TPI tests for us guys who want to maintain the integrity of these cars. I feel like they may be coming back into their own.
Agreed! I bought an old c4 to learn how to work on cars, but totally neglected the lack of info on cars from that era since they are overlooked because of other more desirable generations. I just want 500 hp 500torque out of it. Just hard to figure out where to start since the corvette forums are full of old men who bitch about any questions related to going beyond stock power specs or all the build info are on the later gen c4’s and I have an 85 with the weaker engine but forge pistons from the leftover higher trim models from the c3😂 I need an engine rebuild so might as well give her some extra umph 🎉
@@jakejake7162the corvette guys are the worst. I don’t even consider them car guys it might as well be an investment forum.
500 horsepower and 500 pound feet isn’t something that can be done easily and honestly I’d say if you could knock down 20 numbers from either the power or torque it would be more realistic since these motors only have so many induction systems that make disproportionate power and torque. There really isn’t an intake that will make that power with a stock block unless it’s a built fire breathing 383 with a performer rpm and all forged bottom end. I’m a budget guy so it dont even consider it in my world of expertise lol
@@jakejake7162 You're not getting 500 hp and 500 ft lbs out of a TPI 350 running pump gas, naturally aspirated.
Buy a DART SHP 406 SBC short block, and put some top-shelf 195cc - 210c heads on it, the FIRST fuel injection TPI-style intake, and an AGGRESSIVE roller cam and Holley Terminator to control it and 500 hp / 500 ft lbs on pump gas is EASY. There's no cheap big power with TPI; you CAN make shockingly big power with them vs. what most people think, but it's going to COST YOU.
(I've got a decently budget 440 HP SBC 350 FIRST TPI-based build (if you ignore the cost of the Holley HP EFI system), but I bought all the parts 6 years ago and took my sweet time.)
TPIS
@@jakejake7162 Build a 421 out of a factory 400 block, use AFR 210 heads, or have a set of Profiler heads ported for even more power. (210 heads). You'll be over 500 hp and torque.
Not a fail. The tests prove that a stroker kit is the way to get 500 pound feet from a TPI small block. 465 torque from a 350 is no slouch. It did just what you taught us about TPI motors way back in the day - massive torque. A Comp XFI cam might have made a little more, but building a TPI stroker is the real answer!
Considering the majority out there can't even handle 150 hp in a sub compact car...
lol
@@shadowopsairman1583
465 foot pounds out of a 350 would have been ludicrous in the 70’s and 80’s. Everyone was running torker ii’s and making like 360 foot pounds and the same power number as this motor. I thought my 350 was a torque monster for making 420 foot pounds from a mild roller cam eps intake and world s/r torquer heads. Low end for days and pushed around a heavy square body like a big block.
Throwing in a cam with 107 LCA and 35-40° of overlap will get the right cam needed for maximizing torque which should be around 490 ft-lbs and be 1.4 ft-lbs/CID.
Mill the heads for a bit higher compression. Tune primary length on the 1.75" headers. Tune collector length as well. Add 1.7 roller rockers to take better advantage of the head flow. Scorpion makes them for sbc. I'm running them in my daily driver on my old 92 c1500. Larger throttle body if possible.
I guess youve never heard of port saturation or parasitic stress on the crank. You guy and this massive lift, in most cases high lift loses horsepower. Theres a point (especially with stock heads) where they start to lose power because the ports dont have the ability to flow any better. The stress the added lift puts on the crank due to increasing spring pressure cost horsepower. You use the lift that the heads are capable of flowing and valve springs that dont cause the crank to work harder to turn. Most small block street engines like .450 - .500 lift and 325 - 350 lbs of spring pressure at max lift. Going beyond that does little if anything as far as power is concerned.
106 LSA and 11.5 to 1 compression will get you there. My only issue is that we're limited on airflow with the Tuned Port Injection set up. Also I'm wondering about installing collector extensions with mufflers. You never know until you try. I hope you return to try again. Nice work Richard. Thanks for doing all these test
106 LSA and 11.5:1 is helpful, but it'll knock like crazy on pump gas. Top shelf heads + the FIRST fuel injection TPI-style intake and an aggressive roller cam get rid of the airflow issues, withing the RPM window that you have to work with with the long runners. Long runner engines pushing the boundaries quickly become octane limited. Great quench velocity, cold coolant and cold air help to a certain degree, advanced fuel injection strategies like open valve injection can help a bit more, but if you want to REALLY push a TPI engine, you give it compression and E85. These things cry out for E85. (Get you more oxygen and more knock resistance.)
An E85 all-out FIRST TPI build would be so awesome...
I wish you would get your hands on a First TPI unit and run it..
XFI hydraulic roller cam up to 230 or 240* duration with extreme ramp rates that match larger diameter lifter rollers. Extra high lift. 7MM or 8MM valve stems. 1.7 high average ratio roller rockers. PAC Beehive or other conical high quality springs. 106* LSA. 2.2" intake valve. 1.5" exhaust valve. High attention to detail on AFR 210cc heads or Promaxx Project X215cc heads. Enough swilr and tumble blend with 300 fps velocities in high port energy and efficiency head. A giant single barrel carburetor with a part throttle circuit modification like the Pro 1 single blade carburetor on a dual plane or dual cross ram divided ram intake manifold. Very high cylinder pressure with proper fuel enrichment jetting for WOT. Then with best results slightly enhance results and make a short stroker between 358 and 372 cubic inches. I.E. = 3.5" crank, 3.625 to 3.64 or 3.65" stroke. The 3.5" stroke could net you a 10 ft lb increase. Or a 3.6" stroke would be really nice. Part of the reason the 383 stroker does so well is not only the additional cubic inches. It's bore to stroke ratio is perfectly in the zone of efficiency. So if the stroke and bore was reversed it would be equally in the perfect zone as well.
I think no on the 4/7 or the 4 pattern and you will be hard pressed to find a better head than the AFR, the tighter lsa will work, no on changing the bore/stroke (displacement makes torque)
I like where you're going here. Totally agree on the XFI lobes, but still on a tight LSA and all the extra valve train stuff to control those lobes and more rocker ratio. You're kind of "changing the game" with changing the intake, though. I think the challenge of the limitations of long runner intakes is what "makes it fun".
If you're stuck with the long-runner intake; then a FIRST Fuel Injection super high flowing TPI is a part of the recipe, and I think you want MORE STROKE because you're RPM limited and the extra piston FPS is useful; it also helps provide more quench action to fight the detonation that becomes a risk as you push the DCR of a high performance TPI engine. -Combine the extra stroke with thin piston ring packs to not lose some of the torque from friction (the 1mm ring pack Mahle PowerPak pistons are perfect and reasonably priced).
You COULD do fuel enrichment to fight detonation even with EFI and keeping a long-runner intake, but with a modern EFI system you can also use an Open Valve Injection strategy that helps reduce detonation risk, too.
Best truck intake that never was. Had one in an Iroc-Z and the part throttle drivability and response is something I haven't experienced in anything else. Small cam, Brodix street heads and 1 5/8 headers is a potent little combo.
I want this in a tow truck.
What do you think are good 4wd transmission options for a tpi setup like this? I wanna rip mine out of my vette and throw it in a 2 door wrangler, then figure out something a bit more ballsy for the vette 😁
@@jakejake7162
Easiest would be 700-r4 but idk if the length is good for a wrangler.
Maybe 400
Maybe sm465.
More compression always helps. David has said the 383 is geometrically superior than the 350 because it gains more power than the displacement predicts. This test shows similar.
Yep. The TPI engines are going to have a lower RPM HP peak, so increasing the stroke is super helpful with them as it gets the average piston speeds up AND it gets the quench velocity up which helps reduce detonation risk on these things. A 4"/4.030" bore SBC 396 would be great for a high power TPI build. (Thin piston ring packs become more useful with the higher piston velocities, too.)
Do a first tpi on it richard!!!!!!!!!!!
I'd like to see this motor tested with the FIRST TPI intake.
I agree, tighter lsa and more lift. Usually can get away with lower duration and more lift with roller camshafts. Remember higher ratio rockers add more valve lift everywhere not just peak and thats what adds torque. I love the tpi for truck applications. Currently have a 383 tpi with lt4 hotcam with gt45 turbo.
Occasionally I would see a C4 or an IROC (auto) scoot down the 1/4 mile much better than stock. Besting the LT1 even. And under the hood it looked stock, no power adder. I was thinking stroker and porting. Back in the day.
Hi Richard, I think the first cam you used with a tighter LSA might’ve helped up the torque. Something we learned in your other video and coincides with what David vizard talks about in his books and videos.
Thanks for always producing excellent videos!!!!
Yes, they did the same thing with LSA on Engine Masters (quite?) a few episodes back. Mentioned tightening up the LSA of an oval track car for better "pull" out of the turn.
HEY RICHARD. More aggressive cam lobes... Howard's has a lobe that specs 281 duration 231 at .050 .552lift .589 w a 1.6. Have it ground on a 108 lsa. I have a hunch that tpi engines will respond well to a mild single pattern cam with lots of lift on a tight lsa.
Comp xfi 280, order it on any lobe center you want. Jones cam designs ehr 72360 lobes on a 110-112 lsa would be about the same
@@b.c4066 I'm running the Mike Jones 70375 / 71360 on a 110 LSA in my 350 FIRST TPI build, so I have to agree. ;-)
272/280 ADV, 227/228 @.050", .600"/.576" with 1.6 rockers.
Mike said if i didn't need vacuum brakes, he would've gone a little bit tighter still on the LSA, too...
Try 180 degree headers
My favorite exhaust sound EVER!
Have you tried a first TPI setup? I haven't seen one in your videos. I'm putting one on a 355 just like this one. Be interesting to see what it makes.
I have not
I love your videos, especially the 80s SBC stuff.
Aloha from Maui!
I have a 90 corvette as my daily driver and I'm saving up to have the motor torn down and rebuilt.
As of right now, it has cat delete, x-pipe and 2 aftermarket mufflers.
I would love to have my car make some beautiful music out the pipes and more low end torque for light to light, have a little fun and really don't need top end speed due to living on a small island.
With it as my daily, I am thinking of having it bored 30 over to a 355 instead of a 383 to keep the structurability and from wrecking the engine later down the road, short tube headers, x-pipe and straight pipes all the way.
I've been told that I can keep the original TPI and get up to 400hp and 500 fp torque and those are the numbers that i would really like to see.
Recently I talked to a buddy and he said to slap a charger under the hood and I should be able to see those numbers, but I may run into problems with tuning with the old computer tech from the era.
What say you?
I have been wrenching on tuned port engines since the first one rolled off the truck at the dealership I was working at in ‘85. I have tried lots of combinations with both good and bad results. But honestly, the best I have seen on a 350 TPI is in the 450 ft lb range. A TPI engine is kind of limited to that sweet rpm range. I enjoy torque in a streetcar so it works for me.
Your Y-pipe results are interesting because an X-pipe seems to help mid-range torque with a slight loss at lower rpms.
My current tuned port has absolutely as much material removed from the inside of the plenum as possible because the stock plenum volume is too small with this design. In fact, it’s still too small after mods.
I think that a 383 is probably a better choice if 500 ft lbs is the goal. I have a desktop Dyno sheet stashed away for a virtual 383 TPI that pulled a hypothetical 550 ft lbs. If driving something like that doesn’t put a smile on your face, someone should check you for a pulse.
the 383 made 535 lb-ft, and we didn't test x pipes or y pipes in thsi test-just header design
Yeah it may just come down to the lack of rotating mass at the certain rpm the tpi likes to spin at. The 383 had always been a disproportionately powerful motor that makes uncharacteristic torque for a small block but still capable of high rpm power when built for it. There might just not he enough stroke and rotating mass to take advantage of the tpi’s strengths. As a matter of face there’s a video floating around with a 305 stroked with a 3.75 inch crank to make a 334 and a tpi setup and made some tuning crazy like 430-440 foot pounds. That big crank is the thing that turns the tpi into its own in my opinion but it’s all conjecture so what do I know lol
@@theeoddments960 , My problem with a 305 is that the small bore seems to shroud the valves and reduces airflow substantially. So there seems to be a limit on how much power you can make aside from just the displacement.
I ran a 383 with a Holley 3310 in the 90s and loved it. And I swore by stroke for many years as being the key to torque. But Dyno numbers suggest that it is more about displacement. These days, I believe that aftermarket cylinder heads would give a 377 an advantage over a 383 due to it’s larger bore and better flow potential. It would just breathe better.
@@richardholdener1727 465 ft Lbs? One of my favorite 350 Mag engines did that with an oriental Dual Plane. "Budget Sledgehammer" Sept 22, 2006 Dulcich/Hunkins.. L31 block w iron EQ Vortecs, 10:1 comp w shaved heads/58cc chambers. They used a Vizard spec 224/224 108 LSA cam with 528/563 lift w 1.6 rockers (Comp Cams custom).. You've got better heads than they had, you've got a better manifold for torque than they had .. Use their cam. The mainstays of torque are stroke, size, compression, camshaft .. My armchair suggestion .. Similar spec cam .. maybe up lift to .550 minimum, 11:1 compression with Flatops only- no domes (there are factory sportbikes with this ratio it can be done) max cubes on 350 archetecture.040 over gives you 359 ci .. .060 gives you 362 ci .. 10% of 400 cid is 40 cid.. So a 360 cid engine is 90% of a 400... 90% of a 400 means you'll hit 400 level air demand just a few RPM's higher in the scale. This is a great concept Richard .. 500ft lbs/350.. the power/torque from the 383 w TPIS or Extrude Hone Tune Port manifold was insane .. Inspiring. The factory spec on the 1970 Chevelle LS6 454 was 460hp and 500 tq @ 3600 rpm with 11:1 comp.
Memories... I ran that 218/224 cam in my IROC. (CIRCA late 90s) I think mine was on a 112 or 114 LSA though, maybe I'm wrong? It was another lifetime ago. I had a stock 87 L98 shortblock, that cam, a set of 2nd hand heads off of a ZZ4. It ran well for what it was.
What heads in particular are those? Most AFR heads continue to see improved flow all the way out to 0.600" lift
The duration is probably about right for the goals here, but there is the possibility that 20-30CFM was being left on the table by sticking with the low lift cam.
Perhaps a little overkill but... everyone always does the 383.. I know it's a little extra effort but what about a 396 stroker, fully ported and port matched tpi intake to AFR 195's, not sure what cc chambers would be the best, 65 or 75.., tpis large tube runners, fully ported plenum, comp xfi 268 cam. 218/224, 113 lsa, 568/572 lift maybe, pick a throttle body, whatever you think is best. We all know a stock 48mm can support 500hp. Maybe 24# injectors and one hell of a custom burned ECU chip. If torque is the name of the game then there's no replacement for displacement. This combination could belt out around 480hp and 550tq if my calculations are correct. Now that would be a "bulletproof" street motor. What do you think? Can it be done or am i completely wrong lol. Thanks for all the great videos and content!
I think you might be a tad high on the hp with a TPI and 218 cam
@@richardholdener1727 by"calculations" I think I meant more like speculations. Was I in the ball park tho at least? Solid combination tho? And thank you for responding sir, i appreciate the feedback.
it will make plenty of torque
Im sad that i missed this when you posted it, as I feel a direct correlation to my 500ftlb comment in my L98 on a previous video inwhich you said "a tall order". Pretty damn close, and like i said mine is 470ish. Inwhich I rounded... what man doesnt stretch a bit 😅. Great vid. Thanks for verifying.
the desire for 500 lb-ft from a 350 came right after originally testing the motor (decades ago)
I think your answer is in the early video, you made the area inside the pipes larger without changing the length, and made more everywhere. Probably could use some small exhaust pipe elbows to add even larger volume. Outside of that, I think I'd try to crank up the fuel pressure and some 4 hole injectors, and give it all the timing I could, regardless of how rich I had to run it. I don't know how you'd use an h pipe on a dyno, but using one side of the exhaust to pull on the other might be worth a shot.
Custom cams are expensive: 224/232 @.050, 106 lobe separation, installed @ 102 icl. Cranking compression should be 190-200 for pump gas to work. Just guessing I hope it works. Try this combo with 750 carburetor also 😊
I forgot...this is a Solid lifter cam
My TPI car loves the TPIS ZZ-9 cam. Can’t give you any dyno numbers, it’s never been dynoed. I run it with boost and it runs with boosted LS cars.
My guess would be deck the block and/or heads for more compression, notch the bores of the block to unshroud the valves, a bigger valve package, and possibly a tighter LSA for dynamic compression. My position is allow more intake charge in and compress it more.
Yes Richard, I think the first short duration cam on a tighter lsa 107 would be my pick and maybe a rocker change to 1.65 would put you there.
So sad that I missed this one for 6 months. GREAT set of tests!
As you know increasing torque per cubic inch is HAAAARD. To hit 500 ft lbs, you'd have to make 1.41 ft lbs / cubic inch on a 355, which is a difficult feat without a big budget.
The easy way to hit 500 ft lbs on a 350 inch TPI SBC: Use highly oxygenated race gas; something like CHP+ circle track gas, or E85. Combine that E85 with a bunch more compression and it gets even easier.
A more aggressively lobed cam would help; obviously you have to keep the seat-to-seat durations in the range that are going to work for those long intake runners, so the big option to increase VE at the torque peak is to get more lift with the same seat-to-seat durations. -Higher ratio rockers -yes, moving to a more aggressive hyd roller family like the XFI lobes (but on a custom tighter LSA), or moving to a "street Solid roller".
Compression is obviously useful but pump gas and high compression and high VE is a combination for knock in a real car when you don't have 160F or colder dyno water. Meth injection would help, but so would using an advanced EFI system like Holley HP or Terminator and using a strategy like "Open Valve Injection" and significantly larger injectors that can inject all of the fuel when the valve is open in a small number of degrees / milliseconds: you get more evaporative cooling with this strategy right before the intake valve closes and it allows you to use more compression with the same octane fuel. (Bosch found that they can run with +0.5- +1 CR increase in static compression with the same octane fuel when using an open valve injection strategy.)
I've seen SO many tests of TRI-Y headers now where the TRI-Ys lead to over-scavenging and then a torque drop for part of the curve; that's my suspicion on the TRI-Y test; open valve injection is also ideal in this situation, too, because it can be timed so that injection doesn't start until overlap is over, at least in the low to mid RPM range; then you're not just shooting the fuel out the exhaust during overlap and seeing that torque dip.
Reducing friction where possible can help make tiny gains, too; those Mahle Powerpak SBC pistons with the 1mm ring pack option are a great option to help maximize CR and reduce friction at the same time.
Used David Vizard 128 cam formula.
128-cubic inch÷ number of cylinders÷ intake valve size × .91
Example 128-355÷8÷2.02×.91= 108 LSA
Just curious for the below average guy like me! How does Vizards cam formula work out with factory heads or even the best aftermarket heads & stock bottom?
Can the factory cam be optimized for the stock setup??????
I'd love to come up with the BEST top end package & intake including a custom cam at all costs, but for the below average guy who doesn't want to pull the motor, or have yet to find anyone in S. Florida competent or honest enough to do a full built 383 ect.....
At one point I wanted to put on a supercharger kit & intercooler......so the C4 with 19k miles stayed in storage for many years, due to health problems.
I'm planning soon to carefully get it running & pre-lube the engine with a pre-oiler ect, ect. before even turning by hand. Glad I drained the tank, but not fuel rails, but ill put in upgraded Bosch 22lb EV 1.3 vs. the troublesome Multecs.
My biggest fear is rodent damage since the storage facility once had major rodent problems, so first on the list is 20 traps & Jug of Skippy & Jam .🐁🐁🐁🐁🐁🐁😏
If I find the worst, ill just throw in a loaf bread & let them make their own sandwiches in the front seat & just give up on my dream.🙄
Try a Comp Cams 268h and 1.6 rockers. Back in the day I had a stump puller of a '76 BLAZER with a 383 that cam, flat tops 10-1, 650 double pumper, and an Edelbrock Torker manifold. I know, 383 and Torker are different, but the 268H and 1.6 rockers are solid. I would be curious to see what they would do for you. It was an amazing combo for me! I used Rhodes lifters, remember those???
@Richard Holdener what fuel pressure did you run this at?
58
Ran a 355 tpi at 10.25:1 w/mildly ported iron eagle 180s, lt4 hot cam kit(so 218°/228° .525" on a 113lsa) and the old edelbrock tes headers for a few years before stepping up to a 385 stealth ram setup. My assometer is not certified but 450ish ft/lb sounds abt right. 1st gear with a 700r4 was wonderfully useless
Chevrolet should have put tpi on truck's their mistake. Would e85 increase torque ?
I don't think so
It's incredibly scary to disagree with Richard and his dyno time, but I'm going to 100% disagree on this point and say "yes".
1. These TPI engines are usually oxygen-limited and E85 brings with it plenty of extra oxygen (like an oxygenated race fuel).
2. When you have a real street-driven, high performance TPI engine and you're pushing the dynamic compression to make max power, the big VE can cause detonation around the torque peak RPM in a real car with 200F engine coolant and if you have to pull ignition timing to avoid the knock, you're leaving power on the table. E85 allows you to push the dynamic compression in a high HP / Torque TPI combo without needing to worry about knock, so you can keep all the timing in that it wants. (If you use E85 to push the compression higher, "Certainly Yes".)
The general consensus on these comments seems to be to add more LIFT, go with a tighter cam LSA, add more COMPRESSION to hit 500 ft lbs from a TPI 350. If you go in all three of those directions, the E85 becomes particularly useful, because all three of those things will bring you closer to the detonation limits of your fuel in a real car with real world (not 150F cold dyno water) coolant and air temps.
I'd try adjusting the cam timing. Pull the plugs and set up a compression tester. Test as is then start moving it forward and back until you get the highest compression reading. Then retest. I have feeling you will find more torque at a loss of hp.
From the pic you showed of the Tri-Y header it is basically a shortie header design with pairs of primary pipes connecting at 270* and 450* degrees of crank rotation, which i think usually favors higher RPM operation, and not ideal for the TPI engine. I would have tried to find actual long tube tri-Y headers with the pairs of primary pipes connecting at 180* and 360* degrees of crank rotation, like the tri-Y header version that works so well on the chevy big block, made by a company called Schumacher. I think use of this type tri-Y could help the torque peak. Boosting lower RPM torque is not the easiest thing to do for an engine builder, and you'd usually use things like more mechanical compression and tightening up the LSA on the cam, but other than swapping cams you might just advance the cam about 6* degrees and put a higher ratio rocker on the intake side to see if that might boost up that peak area and get your desired number. Personally, I think that a compression ratio of at least 11.5 would be in order for this type engine especially after you added the larger cam. Inside the TPI plenum you can sharpen up the divider between the ports that feed cylinders 5 & 7 and add more radius on the forward side of the #5 port to cut down on the charge stealing, and this will boost up the lower RPM torque a little. I hope to see you try this test again and get your number. Dan Olympiadis.
All tests are learning opportunities. I think 1 5/8" is just too small at 355 inches. Could use a balance tube as well. Increase rockers test1.6, 1.65, 1.7 for sure. Most of us would rather do a fast rocker swap than a long cam swap. Good video.
Agree 100%!! On all accounts. A stroker would've done it I believe....
me too i think a h pipe may help , 1,7 on that cam use i think it will make it
"1 5/8 is just too small at 355 inches" The late Jack Davis (formerly at Hooker back in the day) would build headers for the 454 powered crew cab dually tow rigs of his and friends drag cars. With 1-1/2" primary tubes about 42" long into 2-1/2" collectors. Pass others on the Grapevine, and at the gas pump.
OK, same small cam but on a 108*, another point of compression , and E30 for fuel (or E85 if that's easier, or equals better availability). I would have used the AFR 180 heads too!
Thanks for sharing! Very well done. Valve timing was all spot on, but I think the big cam told the story. The bigger tubes needed more duration to get the gain in tq. The smaller cam probably would have done better tq yet with the smaller tubes. Pressure wave tuning is completely different than everything upstream of the throttle body, diameter and length both affect Helmholtz resonance.
I think that the crankshaft stroke length has the biggest and most direct impact on torque production.
None of the cool stuff you applied during the tests can increase the stroke length, only changing a crankshaft can do that.
But I have no idea if putting in a crankshaft with greater throws/offset is even an option with that engine.
Cylinder diameter and cylinder wall length, connecting rod geometry, and piston geometry and piston skirt length may already be optimized or maximized for that engine.
Of course, may be missing it as well.
These are just some thoughts that I thought would be worth sharing.
Thanks for another great video.
Take care
we purposely did not want to change displacement (we easily made the number with a 383-harder with a 350
For the same volume there's no difference between stroke or bore, unless it's flow limited and you need the valve size that's possible with bigger bore.
Love the L98 videos. I have an 85 Corvette, and have a TPIS Miniram, Comp Cams 280xfi and AFR195 Comp eliminators sitting on the shelf ready to bolt onto the stock bottom end. Probably a bad idea but I want to give it a shot. I'll just have to set a conservative rpm limit until I have a real shortblock to back it up.
see the mini ram test in the TPI intake video
and the magical tight LSA camshaft for the win. With carb run the tunnel ram intake because it boosts torque across the curve.
I'd like to see a 1/2" 4 hole spacer between the carb and the wilson manifold taper spacer and a 1/2" open spacer under the wilson manifold spacer.
Richard, I didn't pick up where you explained what you were doing for a tune. How are you managing the fuel injection system and timing?
Holley HP or FAST stand alone
11:1, single pattern cam or only 2 degree duration split (221/223) and tighter lobe separation 108, 1.6 rocker for .540-.550” lift.
Which injectors, and where did you get them?
any bosche style injector that supplies enough fuel for your power level will work-we used Deka 80s from Accel
Try to put the 74219 Lingenfelter cam with the superram, with 1.6 roller rockers, use The TPIS headers
Hard to wrap my head around… this exact same combo with a little hotter cam and 3.750” stroke went from 372hp to 450hp. That’s nearly 70hp with just .252” more stroke?
I would’ve figured a ported TPI intake with bigger runners would at least make 400 with AFR 195’s and a cam.
the 270 cam on 108 lsa and more lift. if open to more compression that would help too.
Richard, I think you can get to 500 lb/ft, but it's gonna require 11.5:1 compression and 1.65 rockers on the intake side.....a cam with 108 LCA would be ideal but I think you can still hit the mark with the cam that's in there..........just my thinking on it
Something old something new gm high-tech magazine. 355 tpi with vortech iron heads 416 HP 486 TQ wow
Honestly that 355 in a c4 corvette will be very fun on the street, 372hp and 469ft/lbs of torque would be plenty!
LSA, compression, and maybe even 165s for more port velocity
Just discovered this video! Can't wait to watch the 383 video! How about 1.6 rockers on the intake side with a single pattern camshaft. Better yet a camshaft with more lift on the intake side like the mutha thumper line and what you have already mentioned, tighter lobe separation 106. I don't understand and it was never made clear, why the 1.39 ft/lb per cube formula not only didn't work but was off so much. Thank you for the great video. I'm building a 10.6 to 406 with AFR enforcer 195 heads, .450/.450 218@.050 106 flat tappet hydraulic cam with 1.6 X 1.5 roller rockers and performer eps intake. I am using lightweight rods and lightweight wristpins (156 grams vs. 92 grams) I wonder what kind of power I should expect. I'm guessing 375 hp @ 5100 rpm and 515 lb/ft torque @ 3800 rpm!😀 for my '64 Biscayne with a th350, 2,800 stall and 3.36 gears
This is why I'm building my autocross engine with a LS truck manifold and really long tube headers, and a long duration cam with a tight LSA so it will keep pulling past peak HP without losing too much power. Autocross doesn't need lots of HP at high RPM because the car is not going fast enough to be making much drag so it will still accelerate past peak power if the power doesn't drop too much, and that big cam 383 with the TPI intake only lost 3 HP between peak power and redline. I'm hoping my engine has a similar power curve with the TrailblazerSS manifold and really long tube headers and the Jeg's 295/336 cam.
Thank you for more content on tpi.
Richard, how about a dyno test on a dual plane manifold which has had injectors fitted close to the head ports MPI style. Then dyno test it against the same manifold running a carb. The purpose is to see what happens with the Air/fuel ratio in each cylinder. Will the EFI cause rich/lean cylinders due to uneven air flow but equal fuel application to each cylinder. Especially at low RPM's. Typical manifold would be a Edelbrock RPM air gap.
if you have port injection, you can tune individual cylinder to optimize the af at every rpm (see the video I did on this using the single plane) It will work the same with a dual plane
I think you hit the best possible #s for that configuration.
If I remember correctly, First recommends 224 duration around a 112 LSA. It be interesting to see what a tighter LSA would with the 224 duration. Keep up the good work!!!
It depends if you're keeping the stock ECM or not. Aftermarket EFI will support tighter LSAs and more overlap. You go with a more aggressively lobed cam, you can keep the tuning and the seat-to-seat durations where they need to be and the @ 0.050" durations and lift numbers get bigger, too. Modern EFI gives you a lot more options on these high power TPI builds.
Why didn’t they use TPI on trucks? Seems like it would’ve been best suited for a truck application.
I ran TPI on a G20 van. At low rpm off-idle to 2,500 rpm, it sucks compared to TBI on a dual plane. The TPI only made more torque than the dual plane with TBI from about 2,700-3,800.
@@chrisreynolds6520 interesting
@@chrisreynolds6520 People don't talk about that ENOUGH! TPI are great a MID RANGE, but at RPMS above and below the tuned range, those waves arrive at exactly the WRONG TIME and make a torque dip. (The real reason for TRI-Y headers: to attenuate those waves, so that the AVERAGE power across the RPM band goes up vs. having the big dip on either side of the tuned range.)
In my opinion, it's the stroke that helps produce all that low speed torque . It's difficult to make up for that. It would be interested to see what another point or so of static compression would do. Let's cut to the chase and add some boost.
see the turbo tpi video
I think more lift to take advantage of those heads, and a tighter LSA. Not sure if primary diameter or length would get it there. Aren't unequal length primaries for best scavenging in need of development?
Popup pistons would have pushed it up where you was wanting but mainly the stroke is whats limiting the torque....
1.6 rockers, 11:1, e85, even a blend like e40 or e47 might be enough.
wonder if a fully ported air gap would make the whole thing way easier?
AIR GAP MAKES LESS TORQUE
@@richardholdener1727 i mean, if the new set up made 528, the modded air gap might just make 504 but be way easier to source.
the 383 made 535, but the goal was to make 500 lb-ft from a 350 (the air gap makes less torque than the TPI)
I agree with you. More lift and more compression and then increasing Ethanol gives you the added knock resistance AND more oxygen stuffed into the cylinders.
It has probably been said but tighter LSA on something like the smaller cam (so about 106 lobe separation) and advancing it so it would close the intake sooner and shift torque to lower speeds, like 100 to 102 intake centerline, but along with more octane so timing could be advanced more and/or more compression and timing and octane may have done it. I thought you had testing a F.I.R.S.T. TPI set up but I don't see it....
Some comp xfi hyd roller lobes, around 216/216 on a 105 lsa, 1.6 rockers, and another point of compression. Peak HP might not impress, but should do the trick for making a big peak torque number in the 3500-4000 range
I knew it! I didn't trust those triple Y headers to be better than long 4:1 headers, seeing it well is almost the same 🤷🏽♂️.
To increase power a solid roller camshaft with more lift and duration will help a lot
I had a completely stock 1963 Impala SS with a 327/Glide combo that had Horsepower Engineering Tri-Y headers on it since it was new. In the mid 70's the headers were rusty and leaky, so I had it on the rack at work so a buddy could weld up the leaks. Fired it up, sounded great, start to back out of the shop...and the rack wasn't all the way down, and tore the hell out of the headers. Had to replace them with some Hedman 4 tubes to get back on the road. It felt like I had pulled 2 plug wires off! It was a gutless turd with no bottom end at all! Gas mileage went down, driveability sucked, I couldn't believe the difference.
I agree completely. People don't talk enough about the benefits of a Solid Roller cam on a long-runner build! (I disagree on the Tri-y comments, but that's a much longer conversation.)
A lot more compression. And further optimization of the camshaft including 107 lsa.
On the 383, can we talk about how the Performer RPM made 100 hp more than the stock TPI? Seems like the way to go. Give up some low speed tq, in order to gain 100 hp. Cheaper, simpler, too.
Would be fun to do a setup with 2n or 4 used VW 1.9 - 2.0 TDI turbos on a motor like this just to se how early the boost comes on. Or just 4 really small turbos on any SBC/BBC.... You get those new for like 220$/piece here on the other side of the pond, but used is what is interesting since you almost get them free if they are close to end of life. A tiny budget "other guys" video, excluding engine management cost (there has to be a clever and cheap way of doing that with far eastern stuff?) would be so cool.
Go check out boosted lifestyle he did multiple turbo stuff with dyno results things like 8 turbos on a ls
I like the idea of trying this again with testing cams that have a little tighter lsa. Also how about header collector extensions? Those seem to often help. Are zero-gap rings a thing? There were magazine articles about their benefits in power production back in the late 90s. Maybe one of those articles was authored by you?
I have not tested ZG rings back to back
Tighter flowing head. Keep the port velocity to feed less cubic inches?
Try the thumpr cam with 1.6 ratio on the intake. the tighter lsa and the extra lift on the intake will take advantage of the long exhaust duration and extra scavenging.
tighten lsa from 110 to 108 or to 106. You have to test to see which lsa it likes best, then change duration and test again.
Are the heads as-cast (not ported or cnc at all)? I believe a good smaller port in the 170 range, a stock hand-ported base, stock runners blended/raidused at the plenum (opening the plenum like you would to siamese a pair of runners), and a custom cam you'd hit your number... might even make more power too!
I want to say the short primary section of the tri-y setup is what hurt low end torque. I don't know enough science about it yet, but I have no reason to NOT believe the long primary size of the regular longtubes don't offer the same benefit to low-end torque like TPI does.
Here goes. 13:1 compression, 1mm rings, 2.05/1.72 valves with 30 degree seats, a solid flat-tappet cam with 220/236 @.050 and .525 lift with 1.6 rockers and 108 LSA installed 6 degrees advanced..and a bag of ice on the plenum.
I would have tried a 106 or 107 LSA cam. A little more compression and 1.6:1 rockers would have helped too. One of the magazines ran a Vortec TPI with a SDPC lower intake and got like 489 ft lbs of torque on a 355 SBC, so a little more playing around and you could get there. You might want to talk to David Vizard and ask how to eak out those last few ft lbs. I would love to see how a TPI power curve looks on a mild 400 SBC. Torque, torque, torque! That would be a killer truck set up!
a monster
With 130° coolant temperature, 190° oil temperature, no water pump, no intake filter, no alternator, and open wheel modified headers that will never fit in a street car chassis and maxed out timing they got that. What those kind of tests do not show you is.. run it in that state for 1-2 minutes at normal operating temp and it will die. Take magazine article tests with a grain of salt. They are paid for advertising parts, high power numbers sell parts. If all you want is a trailer queen for the track sure! But who builds a track only car then strangles it with tpi? Build a 383/400 use a well ported first performance tpi with afr 195 comp eliminators, 10.5:1 compression and around 280/280 advertised, 228 to 232 @ 50 with as close to .600/.600 lift as you can get, keep quench tight (.035-.039") and it will make 500+ foot pounds, 435-465 HP. Make sure the piston crowns and combustion chambers have been softened, no sharp edges, use a decent 1-3/4" primary around 30-34" long, 3" collectors, full 3" dual exhaust with good dynomax super turbo mufflers and at least a 2500 rpm stall converter with a well built 4l60e. It will make close to 350-375 rwhp, 400-440 rwtq if you build the drivetrain right, in a 3200 pound car it's a super simple easy low 12 second car that can actually be used and driven daily without cam surge, overheating, or destroying the valve springs every 10,000 miles. Not cheap, now days simpler to just get a 6.0/6.3 LS with mild cam and springs.
Try the stock runnters. Your ported runners are meant to overcome restrictions at higher RPMs. The factory TPI was designed for low end torque. Limit lobe overlap. more overlap results in lower real world compression, less torque. Not even sure the 500 lb-ft is the right measure. Torque is best felt at lower RPM applications. You don't "Launch off the line" in streat applications at 4000RPM. You need to maximize torque at 2000RPM to have a great streat car.
stock TPI makes less hp and less torque-we tested that-overlap is not your enemy (even for torque) and 500 lb-ft is the metric
@@richardholdener1727 Less HP is fine on a street car if it is sacrificed for a flat torque curve that starts no later than 2000 RPM and gets over 400ft/lbs by 3000. However, I realize now you are just making entertainment, not doing anything practical or helpful. I Got a hint with that with your destroker/stroker vid where you changed so many variables your results were meaningless. Time to quit wasting my time. Adios.
12.5:1 compression the bigger cam or maybe a touch bigger and e85.
500 lb/ft divided by 350 CID = 1.43
It is said that only the top 10% of engine builders can manage building 1.35 lb/ft/CID engines and only the top 1% can manage 1.40 lb/ft/CID.
NA engines of course.
it is a lofty goal
@@richardholdener1727 It definitely is. Maybe to lofty. Not impossible but close for most of us because a SBC with 3.75 " stroke is more efficient than all the ones with less stroke. I believe one need "high" pistonspeed, "high" airspeed , "high" valvespeed and 108 LSA camshaft with 224 +/-2 degrees intake duration at 0.050. Speier ported heads on a stroked 307 CID engine. ;) :D
I built a 355 then 383 in 1989 and used a cam dynamics 306 enforcer on both engines with a 106 lca. I have to say i couldnt believe the torque from that cam. No dyno results but seat of the pants. Lol.
Sounds incredible to me. I have a vortec 350 in my suburban and this is on my radar!
That first 350 he showed would be great in a GMT400 Burb.
Yep!
What year?
I think the tri-y headers were not the best example of what a good set of tri-y headers could do. Increase the primary lengths to that of a good set of long tube 4-1s reduce the secondary y to 18 inches and run a good 3 or 3.5 collectors look at NASCAR or V8 supercar headers. Oh and the answer is always boost gt45 cheap China turbo or a good China Gt3582RS something like a PSR or a factory Garrett from a xr6 turbo
I think the tri y headers only work better with the ford firing order. BMW, Merceds have also offered tri y exhaust from factory, but they all share the firing order with the late model ford.
@@danr9584 yes and no Honda's seam to respond to tri ys better than 4-1. The issue is it's very easy to get any set of 4-1 headers to work while a good set off tri ys takes alot of math but even more testing as the range at which they really work will be different for each engine combo. I will definitely agree Ford's are easier to get to work saying that I tried 4 different brands of tri ys on a 4v 5.4 before working out what primary and secondary dimensions worked best throughout the entire rpm. I still maintain that well designed tri-ys will out perform 4-1s look at motorsports very few V8 American/Australian racing cars that run 4-1s (again talking about the big league ppl NASCAR etc)
You have to get the compression up to 11. 25 to 1 to get the power per cubic inch up!
The problem is 11.25:1 with the high VE at a torque peak between 3,500-4,500 RPM makes it a knock-monster in a long-runner build. You have to run the cam in the range that it's going to make power, and then you get skyrocketing VE on these long-runner builds at that torque peak and you get knock even on 93 octane pump gas with cool coolant and a cold air intake and you have to pull timing around the torque peak and the power per cubic inch goes back down from having to pull timing to run on 93 octane (On the WestTech dyno with the water set at 150F, it might be ok, but in a real car... It's a problem.)
A good long-runner TPI build on 93 octane makes it tough to avoid knock even at around 10:1. -I agree with you completely on the approach, but then these engines become knock-limited (they cry out for E85)...
I think a narrow lsa cam around 106, maybe mill the heads a bit and bit longer primary s headers could do it
Imo I’d run a tight LSA and adj the duration for a decent idle quality.Unfortunately people do the opposite when they try to get a decent idle quantity.
I have a 385 ci don't know cam but it has Accel superram with edelbrock lower AFR Heads 10-1about 400 wheel horsepower
Go tighter LSA and more lift. Watch that the max cam lift timing matches torque peak.
Im guessing the restricive TPI and bigger head intake port is creating a volumetric inefficiency. Or, fuel fallout
think torque and runner length
My first change would be a pair of Extrude Honed Dart 200cc cast iron heads so the engine would keep compression that aluminum heads would lose. 2.05/1.60 valve package, a roller cam with a .050 duration of 218°int and 230°exh, .520 lift int and .535 lift exh, and a 112 LSA. And instead of a 355, I would go with a 4.125 bore block to unshroud the valves and have a 372. Keep the same TPI combo from the original test. Flat top pistons, with a modern ring package and dual valve reliefs. 1 3/4" diameter, long tube headers into a pair of Flowmaster 4-2-1 collectors and a 3" X pipe. See what happens.
BIG NO ON THE IRON HEADS
@@richardholdener1727 , can you give me a reason why you would say no?
11.1 compression, more lift with a good Roller rocker use cam with tighter lsa. A switch to a 180 cc head from arf may help, for torque you def want to maximize the velocity of the head. I am going to be using a 170 cc edelbrock head that will come out to a 18ish cc head and will flow around 270 at max but have killer 250 numbers in midrange. Add some good engine oil maybe a windage tray with baffle and crank scraper. If that gets you close add a first tpi and then have that manifold worked, i think it could be done, my combination will be similar but with all the things ive said, i calculated 500 ftlbs minimum at about 4k and 420 ish hp at 5200 to 5500 or so....will shift that at 6k and hope for mid 11s in my camaro.
no on the smaller port heads
Look at the FLOW for the cross-sectional area between the 180cc AFR head and the 195cc AFR head. The 195cc is the velocity "sweet-spot". Velocity is determined by the amount of FLOW per the cross-sectional area; it's counter intuitive, but you CAN have a bigger port that has more velocity than a smaller port.
Larger tri-y's with an ordered 8-4-2-1 configuration will flatten the torque curve; not make "more" peak torque. Of course, it's gotta be dialed in, not just bolted on. Otherwise, when all else fails: just get the burnt air OUT as fast as possible (4-1 large and long tubes with good collectors).
So the big cam in the 383 gave the long runners more time to fill the cylinder, should have tried the 383 cam in the 355.
no
Haha. OK, shoulda run a smaller cam in the 383 as you said, but the 383 did pull a bloody good torque number with that biggish cam. @@richardholdener1727
Thanks Richard! All very informative. I have 4x tpi sbcs in C4 Corvettes. 2x383s, 2x350s, 2 have Super Rams, 1 has an old Paxton SC...How about building a 350ci TPI from a 305 block with a 4" stroke? If you can get a good flowing head on the smaller bore, I'm guessing you'll get 500ft/lb with 4 inches of stroke.
I FEEL (AND TESTING SHOWS) THE DISPLACEMENT IS WHAT MAKES TORQUE-NOT JUST STROKE
Could try some 1.4 rockers with that big cam. Never now.
THE TPI was sized for 305 original. To get more power out it you would need Edelbrock manifold and runners.
the edelbrocks made less torque than this combo
@@richardholdener1727 To gain torque you could have used an old Header by Ed catalog advice, and cut up the 4 into 1 header and ran the set up into a 4-1 collector. If done right, you coulc have flattened out the torque curve some more.
Have You tried L98 350 (355) with higher lift? Lingenfelter made camshaft with 0,560/0,560 inch lift to use with Superram intake. That cam is short in duration 219/219@0,50. As an alternative I like also Comp cam XFI 218/224 cam with 0,57/0,565 lift. I am trying to choose which of these to cams to buy for my SBC 350 89' Corvette. It has Superram, ported 113 heads, forged pistons and oldschool Paxton supercharger, Crover Enduro roller rockers 1.6/1.5, tri y headers.
I would pick the 218/224 cam and not worry about the higher lift
These tests always make me feel conflicted, I have an old TPI engine that is due for a refresh and I think I should hop up, but in the end I know if my goal is easy power I can get it out of a 6.0 LS so easily. If Super Ram intakes hadn't become so silly expensive I'd probably run one of those on top of a 383 just for the nostalgia factor.
Stick to sbc....!!!!
Represent!!!
Torque is king!!!!!
I had 355 that would leave an eleven marks doing 55 to 60 on the highway!!!!!!
🥺😢
I miss my 90 silverado!!!!!!
I'd love to stick with the SBC and tpi and keep my car "period correct", but as you said, LS power is just so damn easy. And unfortunately all those good old intakes are prohibitively expensive for me.
About 10.2:1 compression, heads with smaller cc intake runners with 1.94, 1.6 valves, higher lift camshaft with 107° ish lsa, high flowing 4 into 1 long tube headers would be my thoughts
108 LSA?