Good to know going with the 1 3/4 headers for steering shaft clearance didn't cost me any power on the ole 6.2. 2010 Silverado 6.2 Speed Engineering 1 3/4 and ORY. I asked you about 2 weeks ago this very question and you made these two videos. You really kick ass.
Interesting. Given the boost drop, i’d say there was a restriction and the bigger header did make a difference. Maybe not a restriction issue, but better cylinder evacuation with the larger header. But that one degree of timing at those HP levels could easly be responsible for a big portion of the gains.
I honestly think the timing didn't do much because the lines match down low. I think the increased flow allowing for better cylinder emptying gave the extra power.
@@christianmeeks4430 He said he only added timing from 4400 rpm+ so down low should be accurate as far as the 2 header sizes tested. He mentions that at 9:43
I love how this guy listens to the viewers. If you are building an engine you can find pretty much all of your answers right here on this channel. I don’t know why this channel isn’t more well known. Anybody that asks me performance related engine questions I always refer them to this channel.
I've been stressing, thinking I needed to find a good deal on 1 7/8" headers. That difference has not been worth worrying about. I will call Holley and order the 1 3/4" headers this morning. A great video as always. Thanks Richard.
Slightly off subject but somewhat applies . I tried 1 7/8 on a G Body swap and ran into several interference problems . Then bought a pair of 1 3/4 ...... problem solved !
Great minds think alike!!! I'm trying to find a 1 3/4 long tube system for my G8 to hopefully avoid any fitment issues. Do you think a mini starter would be worth it for weight savings and ease of fitment too?
@@WhaleRacer I bought a set of 1 3/4 Pypes tri-y style headers for my G8 that fit nicely a few yrs ago. American Racing Headers (ARH), or Kooks are very popular for our cars. Both should fit perfectly, but I'd check reviews on fitment. The steering shaft clearance on ours is sometimes an issue, mine have plenty of clearance there.
@@WhaleRacer Starter clearance I don't believe is an issue for us. Car makes 358/375 With Vararam, headers and tune. Roughly factory rated flywheel power, but at rear wheels. About 60+ more at tire compared to stock.
I've got a mild Gen 2 LT1 build. 355 cubes, forged rods and pistons balanced to the stock crank, 10.3:1 compression, ported stock heads, Tick Performance cam, Vortech V1-S making roughly 7psi @ 6500rpm. I put it together with ceramic coated 1 3/4" longtubes, all controlled with a Holley Terminator X. Haven't had a chance to get it on the dyno yet but it pulls strong AF lol. When this comes apart for version 2.0 I'll add a forged crank, 4 bolt splayed cap conversion, aftermarket heads like some AFR's, a bigger cam from Tick, and a smaller pulley on the blower. That'll be the time I go to 1 3/4" stepped to 1 7/8" headers.
I truly enjoy these tests, myself... nothing I build is a dedicated "racecar." So I tend to err on the small side, 1.75" primary headers would be my choice 99% of the time. I like the thinking on the exhaust port, it is a factor few people consider. I'd like to see it done on a set of junk heads for giggles - even though I think we all know what the result would be. But, humor me... how about opening the exhaust port to match the size of the hole in the header flange, then blending it down into the port? I have a feeling that it would = loss of power and disappointment. But, would be fun to see. Lastly, I had a similar combination to the N/A aluminum 383 you tested back in 2008-2010. It made similar power, and ran 10.70s @ 125 MPH on 93 pump gas in a full weight car.
THANK YOU SO MUCH!!!! WOW!!!! THAT IS A TOTALLY AWESOME & BUILDABLE MOTOR!!!! ANYBODY COULD BUILD THAT FOR THEIR HOT ROD!!! I AM SO IMPRESSED!!!! I AGREE WITH YOU. PORT & POLISH THE INTAKE & EXHAUST PORTS TO FLOW MORE AIR. MAYBE GET A BIGGER THROTTLE BODY IF AVAILABLE. THANKS FOR SHARING!!!
I am willing to bet an LY6, or larger inch Ls will make more difference with the 1-7/8 Absolutely LOVE the comparison done here Richard. You really touch on areas MANY NEGLECT.
Great info here! Thanks Richard! I saw the last vid on this, too, and was surprised by the results - I figured the bigger headers would make much more power up top than they did, and I thought the same with boost. Great stuff!
I have a sbc 406 with a 6-71 and I’m putting on small block to big block adapters on it so I can run the larger and better looking open car sprint style headers
The head port size is not the only factor as often the exhaust gases are still expanding quite rapidly just after leaving the head port. But yes surely a restrictive port will ruin any possibility of power gains from a larger header.
Scavenging is a function of tube length (sets the frequency and thus the rpm range) and velocity (flow and tube diameter). The faster velocity the better the scavenging, but too small and you'll cause restriction at high flow. "Back in my day" 1&3/4" was considered too big for a small block, 1&5/8" was enough for us mere mortals... 😂 I'd say that is still true up to 600 hp or so.
David Vizard has researched best header size. For a correctly spec'd engine combo, he picks header diameter based on the exhaust port flow at the max cam lift.
This is great thanks Richard. I have been watching the Enginemasters header/exhaust/muffler tests while I plan to finish my exhaust. Blown SBC. I already have very good fitting ss 1 5/8 headers. My conclusion is I am best optimising the exhaust inc 3" collectors tuned with a x resonators and high flowing glasspacks. There is more power to be lost in the exhaust than 1 5/8 vs 1 3/4 headers which I estimate at only 5hp at 6000. This may be good advice to someone. Headers are expensive.
I use something similar to the old Ford Fe exhaust manifolds that I welded up myself from some store bought "No Stub Header Flanges." It's basically just a 3" half pipe horizontally over the exhaust outlets, and exits at the end so that each manifold looks like an L shape. That's the best I can describe it. I use it on a supercharged motor. I don't really know if it hurts flow or not, but it sure fits the engine bay easy.
It's been my experience that most roots/screw motors don't really care about header size or length very much but some do. I think it has more to do with cam timing, overlap, and how an individual engine's intake and exhaust "talk" to each other.
Would a higher rpm 7500-8000 rpm 383-408 engine start to have more of an advantage with the 1-7/8 over the 1-3/4, is it more of the rpm along with high power Also if the exhaust port is slightly smaller than the headers does it have a anti reversion type of deal
If this proves anything it takes more ths 600 horse worth of air flow to need a 1 7/8th... Edit: just saw the comment on air flow and exhaust port size. So is it a volumn thing? Can you run a 1 3/4 ehsder to a bigger collector and have the same equivalent volumn in the exhaust? I know post collector the harmonics and scavenging of the exhaust plays a role and exhaust length
I am of the mindset, that you would actually see a power increase, if you matched the exhaust port and the header tube, then do a step series, with a choke at the merge collector. By doing that, you get to keep the exhaust velocity that you see at the port, further down the header. You'd actually might be able to change the cam requirements as well. Think about it...we port the intake track, match and flow the intake to the port, but just leave the exhaust to chance? Slide on over to SpeedTalk, it's discussed plenty over there.
Exhaust port size!!! Oh geez... here we go. Test heads that have been matches exactly to the header primary point of entry - or vice versa... 1 3/4, 1 7/8, 2.0 inch with ports in D shape, rectangular, oval, fully round...
I think the added timing helped the engine breathe better and the headers added to that. When tuning with HP Tuners, you can add timing and see if it is creating a higher or lower pull on the MAF to determine if it's creating more power or losing more power. Since there is no maf, the boost level is where you can get that info from. Another good video.
I play a lot in car audio and headers act a lot like ports in ported boxes. In a ported box, you basically have a controlled leak that boosts specific frequencies There's a lot of similarities between them. To make a ported box play lower you can do 3 things. Make the box bigger (bigger motor makes more low end torque) Make the port longer (longer header primary tube makes more low end torque) make the port area smaller (Smaller header primaries make more low end torque)
that is actually more like Helmholtz Resonance-the resonating frequency of the volume-reflected wave requires traveling the length of the runner (twice), once as a positive then as a negative pressure wave
Hopefully it's not a redundant question. Have you measured the primary lengths (they look close but maybe some differences in # 3 & 7 between the two)? Ideally the same manufacturer would be a nice aba. Know Kooks makes em 1 3/4 & 1 7/8 for the same application. Also wonder if different lengths (not as important) might show different results for preference. Probably would need to be a good bit different in primary lengths for that, idk. If I had to guess, for most people's application a 1 3/4 stepped to 1 7/8 would be best but it'd have to go through the lie detector
I always run 1 3/4 headers the clear better and cheaper on instances. Also 1 3/4 clear most spark plug wires unlike the eBay 1 7/8 that bunt about every stock style plug boot.
My take home: for a daily driver or towing, go smaller. Bigger for high revs for Mo Powah! I drive a manual truck and tow my RV. I rarely go over 3500 rpm… and that’s where these graphs start. I’d live to see these graphs in the more driveable rpm range.
the last couple of videos he made had the dyno runs start at 2000 rpm. And he said for this test, it made no sense for him to start the runs at at say, 2000 rpm, since this is clearly a spicy race-ish setup.
I 3/4 on an lsa supercharged 6.0 with Advanced Induction cathedral port heads.(Brian from T.E.A). On the rx7, long tubes go in from the bottom..clearance is everything, clearance wasn't worth the 5 hp at 6400 rpm.
Any stepped header tests? I know the internet sewing circles say that that the step increases midrange power. I'm curious if any of your tests have reflected that statement.
Do these headers, the 1 3/4” and 1 7/8” sets, have the same size collector/flange? From my own builds aside from the design of a header and scavenging effects changing power curves, I have also seen power differences when using the same style/size header but with different size collector flanges outlets. This hasn’t been with my LS setups but I’m actually referring to my old Honda days as I remember one particular dyno session where I ran essentially two identical 4 into 2 into 1 style headers only one ended at a 2.5” and one at 3”. I was running a 3” exhaust at the time, and the 2.5” flanged header made less power while on the big cam lobe than the 3” flanged piece.
One thing that can't be felt here by strapping it to an engine dyno is what throttle response feels like in the driver's seat. On the street is the 1-3/4" header simply better? Is there a noticeable difference between the two? Will never know how response manifests itself in tests like this.
Smaller engines at more modest power levels probably benefit from relatively small header primaries. Larger engines at elevated power levels probably benefit from larger primary pipes. Or not.
Needing to fab up exhaust for my twin s480 t6 ...on a 496 bbc ..25psi goal . On methonal. Fairly Racey deal for a mud race deal ...if we just build a log type manifold rather than a tubular headers i...are we giving up that much?
Sure like to see a 1 5/8 header test as well, good luck finding them for a LS though. 5.3, 5.7 engines in a true daily SUV. Yes, it Probably ain't that much, knowledge is Power though?
I had a set in a fcar with a ls6 in it. They were mac mid length 1 5/8. I went to kooks 1 7/8 and was really surprised it picked up bottom end power pretty noticeably. If course the kooks were a long tube so not exactly apples to apples but that's what i experienced.
I don’t mean to nitpick, I’m enjoying the vids, but something not being considered is the collector where the pipes merge. The 1 3/4 looks like a mor gradual curve into the merge in the collector. Desirable. The 1 7/8 looks like a shorter and more abrupt merge. Not to mention what the inside looks like. Are the 1 3/4 pinched together where all the tubes touch to form a symmetrical “+” shape? Does the hookers have that sloppy welding in there where it’s a bunch of weld where the pipes all touch? All of that makes a difference. Theres a few other details, but I’m getting too picky and technical. Anyways, good comparison. Street duty is always better with a smaller header. Wonder if 1 5/8 would be more tq down low.
@@richardholdener1727 it’s quite difficult to describe and convey my thoughts in the comment section. Unfortunately it does not let me post images, picture is worth a thousand words. But more so I was referring to collector design being different for both. But I’m splitting hairs tbh. Just pointing out factors that effect things that the “average “ gear head doesn’t consider. Not meaning to nitpick, I enjoy all the info and I know you can’t please everyone!
I’m getting a 355 Holden built and headers are doing my head in as I’m not smart enough to work out the maths for to work out what size headers at buy, I want 4 into 1’s but unsure on size between 1 3/4 and 1 7/8, engine specs are 12:5.1 comp aluminium 200cc heads cam specs 268/272 720thou lift @50 106lobe sep , it has all the good supporting mods to see around roughly 620+ hp and 7500/8000rpm, Any help would muchly appreciated !!
Thanks Richard! I bought some Speed Engineering 1-3/4" headers for my LS1 based on your tests. The goal is a certain air speed to maximise scavenging...which relates to cylinder pressure when the exhaust valve opens. These new LS cams open the valve so early that they can get away with larger primaries, although it's not the best solution. The speed of sound also changes with exhaust temperature, and 2 stroke engine builders commonly lean out engines to tune the power band.
air speed is not the primary positive pressure wave that returns as a negative pressure wave to induce charge filling, nor is it the pressure wave that follows then passes the actual exhaust flow
@@richardholdener1727 Can you, or some other knowledgeable individual, please elaborate on this?? I don't understand how exhaust velocity is not the primary driver of cylinder scavenging.
@@aaronnoyb I used to confuse exhaust velocity with the speed of the pressure waves too. The sound/pressure waves move at the speed of sound; about 514 m/s in hot exhaust. Obviously air can't move that fast. The ideal exhaust velocity to evacuate the cylinder is 55 m/s. I think it's more helpful to think of Bernouilli than waves. hth
I dont think I have ever seen you go over 38 degrees in timing on an SBC but Bill on Old Mans Garage says that SBC's with decent cams run best at 40 or more.
I’m not Richard, but I know the answer to your question lol. When talking about these factory Eaton blowers and porting, what is done is the outlet on the underside of the blower is opened up to a larger size than it is from the factory. This is the orifice/location where the vanes dispense their boost from the blower and force it down either into the intake manifold or, if equipped, through an intercooler and then into the manifold to the engine. What this does is allow the volume of airflow to be less restricted coming out of the blower, so In theory it allows more CFM of airflow to exit the blower and therefore make more power.
Also, in addition to the opening of the factory port on the bottom of the blower case, some methods of porting will also include boring new holes in the blower case as well, in a further effort to increase airflow of the unit into the engine.
Also it's frequently ported on the intake side of the supercharger. superchargers are particularly affected (negatively) by intake restrictions, so porting the intake, and/or adding a bigger throttle body is almost always a good upgrade.
Stock: not so much. But when you get a cam, intake, tune, etc., the stock headers can choke up the engine. One dude gained 50hp on a cammed LS3 swapping from stock to 1 3/4 headers
Yes! Any LS engine will benefit from long tubes. Even a stock 4.8 will be worth putting headers on. I've got a 2010 Silverado 6.2 headers only into stock catback. It made a nice difference in a 6k lbs truck, in a car it would be very noticeable. From 2k to redline it pulls harder. It also runs smoother with the long tubes on my 87 octane tune.
I have always used 17/8 because that extra up top always helps and I believe buy once headers are always something you can grow into it’s like buying a big turbo just cause you can’t use the power now doesn’t mean you won’t later
Unless you can test each individual combination in a tightly controlled scientific environment, you couldn't measure the minute differences. Moreover, the tiny performance variations might not make a measurable difference at the track. I wish we had an easy button
Good to know going with the 1 3/4 headers for steering shaft clearance didn't cost me any power on the ole 6.2. 2010 Silverado 6.2 Speed Engineering 1 3/4 and ORY. I asked you about 2 weeks ago this very question and you made these two videos. You really kick ass.
Did headers really wake up your 6.2? I have a 2011 6.2 and have been considering long tubes.
Interesting. Given the boost drop, i’d say there was a restriction and the bigger header did make a difference. Maybe not a restriction issue, but better cylinder evacuation with the larger header. But that one degree of timing at those HP levels could easly be responsible for a big portion of the gains.
I honestly think the timing didn't do much because the lines match down low. I think the increased flow allowing for better cylinder emptying gave the extra power.
@@christianmeeks4430 He said he only added timing from 4400 rpm+ so down low should be accurate as far as the 2 header sizes tested. He mentions that at 9:43
@silentbravo Ah ok. I missed that part.
But less heat in the charge thanks to less boost pressure helps facilitate more timing..
I love how this guy listens to the viewers. If you are building an engine you can find pretty much all of your answers right here on this channel. I don’t know why this channel isn’t more well known. Anybody that asks me performance related engine questions I always refer them to this channel.
thnx-go tell a million or so friends
I've been stressing, thinking I needed to find a good deal on 1 7/8" headers. That difference has not been worth worrying about. I will call Holley and order the 1 3/4" headers this morning. A great video as always. Thanks Richard.
I’ve been waiting for this upload especially on the 383 😎
Slightly off subject but somewhat applies . I tried 1 7/8 on a G Body swap and ran into several interference problems . Then bought a pair of 1 3/4 ...... problem solved !
Same reason I went with 1 3/4 on the 88 S10 Blazer dang steering shaft.
Great minds think alike!!! I'm trying to find a 1 3/4 long tube system for my G8 to hopefully avoid any fitment issues. Do you think a mini starter would be worth it for weight savings and ease of fitment too?
@@WhaleRacer I bought a set of 1 3/4 Pypes tri-y style headers for my G8 that fit nicely a few yrs ago. American Racing Headers (ARH), or Kooks are very popular for our cars. Both should fit perfectly, but I'd check reviews on fitment. The steering shaft clearance on ours is sometimes an issue, mine have plenty of clearance there.
@@WhaleRacer Starter clearance I don't believe is an issue for us. Car makes 358/375 With Vararam, headers and tune. Roughly factory rated flywheel power, but at rear wheels. About 60+ more at tire compared to stock.
I'm going through the same thing right now😂
I have always been told that 1 7)8 should be used on a Super Charge motor. Awesome content 👍💯🔥👏
Looks like I'll be getting 1 3/4" for my street driven blown goat
I've got a mild Gen 2 LT1 build. 355 cubes, forged rods and pistons balanced to the stock crank, 10.3:1 compression, ported stock heads, Tick Performance cam, Vortech V1-S making roughly 7psi @ 6500rpm. I put it together with ceramic coated 1 3/4" longtubes, all controlled with a Holley Terminator X. Haven't had a chance to get it on the dyno yet but it pulls strong AF lol.
When this comes apart for version 2.0 I'll add a forged crank, 4 bolt splayed cap conversion, aftermarket heads like some AFR's, a bigger cam from Tick, and a smaller pulley on the blower. That'll be the time I go to 1 3/4" stepped to 1 7/8" headers.
I truly enjoy these tests, myself... nothing I build is a dedicated "racecar." So I tend to err on the small side, 1.75" primary headers would be my choice 99% of the time. I like the thinking on the exhaust port, it is a factor few people consider. I'd like to see it done on a set of junk heads for giggles - even though I think we all know what the result would be. But, humor me... how about opening the exhaust port to match the size of the hole in the header flange, then blending it down into the port? I have a feeling that it would = loss of power and disappointment. But, would be fun to see. Lastly, I had a similar combination to the N/A aluminum 383 you tested back in 2008-2010. It made similar power, and ran 10.70s @ 125 MPH on 93 pump gas in a full weight car.
I think it’s safe to say 1 3/4” headers are sufficient for that engine displacement, power level and RPM and most LS combinations
THANK YOU SO MUCH!!!! WOW!!!! THAT IS A TOTALLY AWESOME & BUILDABLE MOTOR!!!! ANYBODY COULD BUILD THAT FOR THEIR HOT ROD!!! I AM SO IMPRESSED!!!! I AGREE WITH YOU. PORT & POLISH THE INTAKE & EXHAUST PORTS TO FLOW MORE AIR. MAYBE GET A BIGGER THROTTLE BODY IF AVAILABLE. THANKS FOR SHARING!!!
This is what we have been waiting for
I am willing to bet an LY6, or larger inch Ls will make more difference with the 1-7/8
Absolutely LOVE the comparison done here Richard. You really touch on areas MANY NEGLECT.
Great info here! Thanks Richard! I saw the last vid on this, too, and was surprised by the results - I figured the bigger headers would make much more power up top than they did, and I thought the same with boost. Great stuff!
I have a sbc 406 with a 6-71 and I’m putting on small block to big block adapters on it so I can run the larger and better looking open car sprint style headers
Happy I saved 350$ getting a set of 1 3/4 headers for my Mild (6500rpm) 408 LQ4 build vs 1 7/8 after watching this video.
Thank you for sharing your data and explaining it. Your videos certainly help out newbies like myself!
The head port size is not the only factor as often the exhaust gases are still expanding quite rapidly just after leaving the head port. But yes surely a restrictive port will ruin any possibility of power gains from a larger header.
Another solid video from Richard paindinfull really love the data.....
Scavenging is a function of tube length (sets the frequency and thus the rpm range) and velocity (flow and tube diameter). The faster velocity the better the scavenging, but too small and you'll cause restriction at high flow. "Back in my day" 1&3/4" was considered too big for a small block, 1&5/8" was enough for us mere mortals... 😂 I'd say that is still true up to 600 hp or so.
David Vizard has researched best header size. For a correctly spec'd engine combo, he picks header diameter based on the exhaust port flow at the max cam lift.
that does not take into account scavenging
This is great thanks Richard.
I have been watching the Enginemasters header/exhaust/muffler tests while I plan to finish my exhaust. Blown SBC.
I already have very good fitting ss 1 5/8 headers.
My conclusion is I am best optimising the exhaust inc 3" collectors tuned with a x resonators and high flowing glasspacks.
There is more power to be lost in the exhaust than 1 5/8 vs 1 3/4 headers which I estimate at only 5hp at 6000.
This may be good advice to someone. Headers are expensive.
I use something similar to the old Ford Fe exhaust manifolds that I welded up myself from some store bought "No Stub Header Flanges." It's basically just a 3" half pipe horizontally over the exhaust outlets, and exits at the end so that each manifold looks like an L shape. That's the best I can describe it. I use it on a supercharged motor. I don't really know if it hurts flow or not, but it sure fits the engine bay easy.
It hurts flow.. BUT it fits, that's more important.
It's been my experience that most roots/screw motors don't really care about header size or length very much but some do. I think it has more to do with cam timing, overlap, and how an individual engine's intake and exhaust "talk" to each other.
Would a higher rpm 7500-8000 rpm 383-408 engine start to have more of an advantage with the 1-7/8 over the 1-3/4, is it more of the rpm along with high power
Also if the exhaust port is slightly smaller than the headers does it have a anti reversion type of deal
If this proves anything it takes more ths 600 horse worth of air flow to need a 1 7/8th... Edit: just saw the comment on air flow and exhaust port size. So is it a volumn thing? Can you run a 1 3/4 ehsder to a bigger collector and have the same equivalent volumn in the exhaust? I know post collector the harmonics and scavenging of the exhaust plays a role and exhaust length
I am of the mindset, that you would actually see a power increase, if you matched the exhaust port and the header tube, then do a step series, with a choke at the merge collector. By doing that, you get to keep the exhaust velocity that you see at the port, further down the header. You'd actually might be able to change the cam requirements as well. Think about it...we port the intake track, match and flow the intake to the port, but just leave the exhaust to chance? Slide on over to SpeedTalk, it's discussed plenty over there.
Exhaust port size!!! Oh geez... here we go. Test heads that have been matches exactly to the header primary point of entry - or vice versa... 1 3/4, 1 7/8, 2.0 inch with ports in D shape, rectangular, oval, fully round...
I think the added timing helped the engine breathe better and the headers added to that.
When tuning with HP Tuners, you can add timing and see if it is creating a higher or lower pull on the MAF to determine if it's creating more power or losing more power.
Since there is no maf, the boost level is where you can get that info from.
Another good video.
we get the power info-that tells us if timing does anything
I was thinking the same thing about the port size being the restriction and not the headers.
Would love to see ignition maps
I am on team header cuz I know you already tuned it to what it needed on the smaller headers.
It would be interesting if you compared the factory exhaust manifolds vs. the headers. Are headers worth the money and fitment headaches?
they are worth a lot over stock exhaust manifolds-those videos are up
I play a lot in car audio and headers act a lot like ports in ported boxes.
In a ported box, you basically have a controlled leak that boosts specific frequencies
There's a lot of similarities between them. To make a ported box play lower you can do 3 things.
Make the box bigger (bigger motor makes more low end torque)
Make the port longer (longer header primary tube makes more low end torque)
make the port area smaller (Smaller header primaries make more low end torque)
Perfect analogy!
that is actually more like Helmholtz Resonance-the resonating frequency of the volume-reflected wave requires traveling the length of the runner (twice), once as a positive then as a negative pressure wave
Hopefully it's not a redundant question. Have you measured the primary lengths (they look close but maybe some differences in # 3 & 7 between the two)?
Ideally the same manufacturer would be a nice aba. Know Kooks makes em 1 3/4 & 1 7/8 for the same application.
Also wonder if different lengths (not as important) might show different results for preference. Probably would need to be a good bit different in primary lengths for that, idk.
If I had to guess, for most people's application a 1 3/4 stepped to 1 7/8 would be best but it'd have to go through the lie detector
Definitely wish it was a straight up test and not added timing but still a good test.
I always run 1 3/4 headers the clear better and cheaper on instances. Also 1 3/4 clear most spark plug wires unlike the eBay 1 7/8 that bunt about every stock style plug boot.
I'm wonder if you can do a back to back test on a stock cam vs stock core regrind cams
My take home: for a daily driver or towing, go smaller. Bigger for high revs for Mo Powah!
I drive a manual truck and tow my RV. I rarely go over 3500 rpm… and that’s where these graphs start. I’d live to see these graphs in the more driveable rpm range.
the last couple of videos he made had the dyno runs start at 2000 rpm. And he said for this test, it made no sense for him to start the runs at at say, 2000 rpm, since this is clearly a spicy race-ish setup.
I 3/4 on an lsa supercharged 6.0 with Advanced Induction cathedral port heads.(Brian from T.E.A). On the rx7, long tubes go in from the bottom..clearance is everything, clearance wasn't worth the 5 hp at 6400 rpm.
Ok you started it. I'd like to see 1.625 and 1.5.
Killin it Richard!
Any stepped header tests? I know the internet sewing circles say that that the step increases midrange power. I'm curious if any of your tests have reflected that statement.
it doesn't
Port match exhaust just like the intake ports.
What we learned: if under 800hp, 1 7/8 is fine. If over, it's still fine.
What we really learned was 1 3/4 is good up to 650-750 for clearance purposes. And even at that power it's still only loosing about 15-25HP.
Personally I blame squirrels
Do these headers, the 1 3/4” and
1 7/8” sets, have the same size collector/flange? From my own builds aside from the design of a header and scavenging effects changing power curves, I have also seen power differences when using the same style/size header but with different size collector flanges outlets. This hasn’t been with my LS setups but I’m actually referring to my old Honda days as I remember one particular dyno session where I ran essentially two identical 4 into 2 into 1 style headers only one ended at a 2.5” and one at 3”. I was running a 3” exhaust at the time, and the 2.5” flanged header made less power while on the big cam lobe than the 3” flanged piece.
collector design and size can certainly change the power curve
Love this type of information!
There will always be a trade, the question is, when do the upsides outweigh the downside
One thing that can't be felt here by strapping it to an engine dyno is what throttle response feels like in the driver's seat. On the street is the 1-3/4" header simply better? Is there a noticeable difference between the two? Will never know how response manifests itself in tests like this.
Try to do 2” headers please so we can see if it’s worth it going from 1 7/8 to 2” stroker N/A set up 🤘🔥🙏🙏🙏
You don't need a 2" primary unless you're in blown alchohol territory
if the 1 7/8 only added 3-5 hp, the 2.0 isn't necessary-except on the blower motor possibly
my guess is you'd loose even more power down low and gain nothing up top whatsoever
I guess I'm good then with my 1 3/4 headers. My mild 496 made 565hp/600tq
Smaller engines at more modest power levels probably benefit from relatively small header primaries. Larger engines at elevated power levels probably benefit from larger primary pipes. Or not.
Needing to fab up exhaust for my twin s480 t6 ...on a 496 bbc ..25psi goal . On methonal. Fairly Racey deal for a mud race deal ...if we just build a log type manifold rather than a tubular headers i...are we giving up that much?
only if you are looking to max out the turbos
Sure like to see a 1 5/8 header test as well, good luck finding them for a LS though. 5.3, 5.7 engines in a true daily SUV. Yes, it Probably ain't that much, knowledge is Power though?
I had a set in a fcar with a ls6 in it. They were mac mid length 1 5/8. I went to kooks 1 7/8 and was really surprised it picked up bottom end power pretty noticeably. If course the kooks were a long tube so not exactly apples to apples but that's what i experienced.
I don’t mean to nitpick, I’m enjoying the vids, but something not being considered is the collector where the pipes merge. The 1 3/4 looks like a mor gradual curve into the merge in the collector. Desirable. The 1 7/8 looks like a shorter and more abrupt merge. Not to mention what the inside looks like. Are the 1 3/4 pinched together where all the tubes touch to form a symmetrical “+” shape? Does the hookers have that sloppy welding in there where it’s a bunch of weld where the pipes all touch? All of that makes a difference. Theres a few other details, but I’m getting too picky and technical. Anyways, good comparison. Street duty is always better with a smaller header. Wonder if 1 5/8 would be more tq down low.
sloppy welding changes nothing-even big dents change nothing-collector design can change the power curve
@@richardholdener1727 it’s quite difficult to describe and convey my thoughts in the comment section. Unfortunately it does not let me post images, picture is worth a thousand words. But more so I was referring to collector design being different for both. But I’m splitting hairs tbh. Just pointing out factors that effect things that the “average “ gear head doesn’t consider. Not meaning to nitpick, I enjoy all the info and I know you can’t please everyone!
1 upgrade, at the time. Headers, then timing. Let, us see headers, then timing.
Thats a stout engine! Nearly 600 hp out of a 383. Nice!
What kind of HP do you think a stock rotating assembly and aluminum block 6.2 ls handle max and then reliably
we don't take the LS alum block above 1000 hp
Enlightening
I’m getting a 355 Holden built and headers are doing my head in as I’m not smart enough to work out the maths for to work out what size headers at buy, I want 4 into 1’s but unsure on size between 1 3/4 and 1 7/8, engine specs are 12:5.1 comp aluminium 200cc heads cam specs 268/272 720thou lift @50 106lobe sep , it has all the good supporting mods to see around roughly 620+ hp and 7500/8000rpm,
Any help would muchly appreciated !!
I doubt you see much difference but I would be tempted to run 1 7/8 on that
Thank you for the reply Richard! I love your channel mate. Cheers!
I want 2in headers for my ls3 with ported heads but mainly if i ever go ls7 ill havum & i herd 5hp gain goin from 17/8 headers too 2in above 6k.rpms
Would the header results be the same on a 454 bbc in the 500 to 600 hp range? Im running 2 inch headers, are they too big? Thankx.
that is fine for a 454
I’m using stock LS3 exhaust manifolds on my 4.8 with a summit stage 1 truck cam. Any idea how bad the manifolds are killing power?
TAKE A LOOK AT THE STOCK VS LONG TUBE VIDEO RUN ON A 4.8L
I say 7-8hp on each add 1deg.timing 7-8 hp from 6600rpm to 6700 so on with bigger headers
Thanks Richard! I bought some Speed Engineering 1-3/4" headers for my LS1 based on your tests.
The goal is a certain air speed to maximise scavenging...which relates to cylinder pressure when the exhaust valve opens. These new LS cams open the valve so early that they can get away with larger primaries, although it's not the best solution. The speed of sound also changes with exhaust temperature, and 2 stroke engine builders commonly lean out engines to tune the power band.
air speed is not the primary positive pressure wave that returns as a negative pressure wave to induce charge filling, nor is it the pressure wave that follows then passes the actual exhaust flow
@@richardholdener1727
Can you, or some other knowledgeable individual, please elaborate on this??
I don't understand how exhaust velocity is not the primary driver of cylinder scavenging.
@@aaronnoyb I used to confuse exhaust velocity with the speed of the pressure waves too. The sound/pressure waves move at the speed of sound; about 514 m/s in hot exhaust. Obviously air can't move that fast. The ideal exhaust velocity to evacuate the cylinder is 55 m/s. I think it's more helpful to think of Bernouilli than waves. hth
@@aaronnoyb
. B
I dont think I have ever seen you go over 38 degrees in timing on an SBC but Bill on Old Mans Garage says that SBC's with decent cams run best at 40 or more.
THE CAM HAS NOTHING TO DO WITH TIMING REQUIREMENTS-THAT IS MORE THE PISTON AND CHAMBER DESIGN-MORE TIMING MEANS AN INEFFICIENT CHAMBER DESIGN
@@richardholdener1727 cool, I just found it odd that he was advocating for such high timing. So its more about the heads than the cam.
I’d be interested in seeing an 1 7/8” stepped 1 3/4” header in this mix.
I have tried step headers too
Richard, could you please explain "porting" a blower. That is a new term I would like to understand. Thank you so much.
I’m not Richard, but I know the answer to your question lol. When talking about these factory Eaton blowers and porting, what is done is the outlet on the underside of the blower is opened up to a larger size than it is from the factory. This is the orifice/location where the vanes dispense their boost from the blower and force it down either into the intake manifold or, if equipped, through an intercooler and then into the manifold to the engine. What this does is allow the volume of airflow to be less restricted coming out of the blower, so In theory it allows more CFM of airflow to exit the blower and therefore make more power.
Also, in addition to the opening of the factory port on the bottom of the blower case, some methods of porting will also include boring new holes in the blower case as well, in a further effort to increase airflow of the unit into the engine.
@@kennethpowers8995 Thank you so much. Just what I thought. So all the ports match. To increase airflow.
the porting would and should also include the inlet side of the blower-throttle body size opening and opening into the rotor pack
Also it's frequently ported on the intake side of the supercharger. superchargers are particularly affected (negatively) by intake restrictions, so porting the intake, and/or adding a bigger throttle body is almost always a good upgrade.
Is it actually worth swapping out stock ls3 headers power wise?
Stock: not so much. But when you get a cam, intake, tune, etc., the stock headers can choke up the engine. One dude gained 50hp on a cammed LS3 swapping from stock to 1 3/4 headers
Yes! Any LS engine will benefit from long tubes. Even a stock 4.8 will be worth putting headers on. I've got a 2010 Silverado 6.2 headers only into stock catback. It made a nice difference in a 6k lbs truck, in a car it would be very noticeable. From 2k to redline it pulls harder. It also runs smoother with the long tubes on my 87 octane tune.
I have plenty of stock ex manifold to long tube header videos up
@@richardholdener1727 yep watched them now. Cheers Richard
Diverging lines is an airflow gain, not a 1 degree of timing gain.
TIMING NEAR THE POWER PEAK DOES THE SAME THING
@@richardholdener1727 even just 1 degree over such a wide rpm window? Thanks for taking the time to reply.
The NA combo would’ve done a bit better with some aftermarket heads
the na combo had cnc ported 243s-see the big head test video to see why those heads are not a restriction to this combo
@@richardholdener1727 I’ll check it out. Thanks for the reply
I have always used 17/8 because that extra up top always helps and I believe buy once headers are always something you can grow into it’s like buying a big turbo just cause you can’t use the power now doesn’t mean you won’t later
Would a 2 inch header be Useful on a 6.2
not in my testing
@@richardholdener1727 what would be the best size for a TT 6.2?
How much boost can I run with stock TTY heads bolts? ; )
1.7 psi max
Is there some math you can use to estimate?
"threw the kitchen sink at it" pfhahaha
Unless you can test each individual combination in a tightly controlled scientific environment, you couldn't measure the minute differences. Moreover, the tiny performance variations might not make a measurable difference at the track. I wish we had an easy button
So basically if you've already got 1 3/4 headers don't waste your time changing to 1 7/8 because you'll only pick up 5 or 10hp 😂
What's funny is most trucks would benefit from 1 1/2" headers yet nobody makes them.
Because bigger is better you know.
not sure about 1.5 inch headers-maybe 1 5/8?
Wheres the nitrous test???
JUST ADD 100 HP TO EACH-BOOM, DONE!
Ahhh.... I reluctantly agree 🤣🤣
🐿🐿🐿🐿🐿🐿🐿😎😁