PUMP GAS TURBO-WHAT WORKS BEST?
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- Опубліковано 30 вер 2024
- DYNO RESULTS-COMPRESSION vs BOOST-WHAT WORKS BETTER on Pump Gas? Higher Compression/Lower Boost or Lower Compression/Higher Boost? The higher compression allows the 706 heads make more power than the 317 heads-both NA and Turbo, but what about on pump gas? Can the low compression compete with added boost and/or timing? Plus, we revisit three previous videos for updates.
I’m no professional, but here’s my opinion based on what I just did. So o had a 10.7:1 5.7ls1 in my gto. Pump 93. I could only run 11 degrees of timing at 11-12psi and if I added one more I’d pick up knock in my hp tuners scanner and I could hear it clatter when I shifted to 3rd gear. So based off of that, I wanted to run higher boost (I broke a piston in the 5.7 from detonation, I leaned it out to 11.7 afr and it clattered and I didn’t let off) so I built a lower compression 5.3. Same cam. Same heads. Same intake. Turbo. Everything except engine size and compression. New motor is 9.4-9.5:1. I’m running 15psi, 14-15 degrees timing. Feels about 100hp stronger. I ran it on 19.6psi (accident lol) the other night, 14 degrees, 93 pump and it didn’t clatter nor did my log pick up knock.
My take: higher compression will work, however, it’s more dangerous and the line you may cross from safe to dangerous....is much thinner than with lower compression. I feel like the lower compression allows more boost, more timing and more power. I could probably run 87 octane on 8-10psi.
If you could pull this test off, it would be epic.
Lower compression plus opened ring gaps are the recipe for stock boost applications. Higher compression can help hp numbers sure, but in stock form those pistons and rods will thank you later with lowered compression. This is why many people run 9:5:1 or lower while adding forced induction. This small step can save lots of time and money in the long run and your story is a perfect example. And obviously the higher the octane (93) has less risk of causing knock and detonation especially under heavy load. Why run 87 when 93 is at the same pump and super available. Heck I would love to use ethanol for that matter but it’s not available in my area.
Suq Madiq yep. I was at the drag strip chasing a number and got greedy. Otherwise, it might still be in the car. But no matter, the 5.3 is much stronger and I can beat on it more. More room for error.
I agree. Done similar in my little 4 banger. Running 8.5:1 on pump. 21psi all day. Lower comp may loose a little throttle response but once on boost, all good.
I agree. Done similar in my little 4 banger. Running 8.5:1 on pump. 21psi all day. Lower comp may loose a little throttle response but once on boost, all good.
@@boosthit811 If you can get in and mess with the timing curve before boost that trade goes away. Basically stronger "vacuum advance". Once I got that part right, it felt NA like before boost, and didnt give up anything into boost. I go up to around 20-22psi, on pump gas, no I.C., no waste gate, 8.0:1 cr. I've been out as far as 20 degrees at that boost level, it just felt a lot better at 18 degrees.
The problem I havr saw with 317 heads on a 5.3 or 4.8 is the combustion chamber is larger than the bore diameter so the air coming in the intake valve hits the head gasket and top of the block before it goes in the bore killing power
Richard, I would definitely love to see a video comparing the compression on boost with an octane limited fuel. I had this same dilemma when choosing pistons for my Subaru motor. I went with the lower compression of the two just because the internet said to use lower compression with more boost, but I always wondered if I could make the same peak power and have more power before any boost builds (daily driving stuff) with higher compression.
I lost a piston to factory ring gap and a bad injector in my boosted LS7. Just had Texas speed put together a low compression 427 because I can always feed it more boost, but I can’t decrease static compression, unless I stuff another piston that is. I want pump gas and factory reliability. So I chose the safe and forgiving route. It shouldn’t sweat IATs at the track as much ether.
@@TheTmshuman and Brett, what compression did you guys end up choosing?
For snappy engine feel 10-1 is fine for pump on boost look at the new mustangs/camaros I think they are 11-1 and running pump gas making 700+ on pump the only time I would see running low compression is if you have no boost control or plan on 1000+ hp for pump 10-1 in my opinion is great also talk to your tuner and ask before you build what they are comfortable tuning and set ups they have seen be successful
First mistake was building a Subaru motor.
@@knorespect7403😂
Take a piece of 1/4" copper tubing and bolt it to the engine, just pinch it under a bolt on the side of the block. Then run that tubing back into the control room and put a cut top of a 2 litre bottle over the tubing like a megaphone. you will positively be able to hear the detonation when it happens.
I've seen it run into a set of hearing protector "ear muffs" works the tits,
I've done engine development in top-flight facilities, that had multimillion dollar in-cylinder pressure transducer systems. The old copper tube method straight up works better.
Would this copper tubing trick also work in a car .., while driving it around..?
@@hemi-denny Sure does.
The basic camps are the old school turbo LS projects built between 2001-2009 when we targets 9-9.5:1 compression to run on 91/93 octane on the streets and that dumped in meth injection or C16 to max effort at the track, and those built after 2010 where E85 started to become available and used the 10-10.5:1 stock compression.
So, a test mule that's in the 9-9.5: range and a test mule at 10:1 would work fine. It's cheaper to build the test mules with different heads and/or gaskets to hit those desired compression targets, but we do have the variable of the head flow. I think we can accept that impact but if we can't, then use the same heads with different piston in each mule.
We'd run the tests with each engine on 91 or 93 and E85.
See what HP they make and the max timing at a targeted boost of 10lbs and note the timing for each fuel.
Then run the test with max at two locked timings (say 15 degrees and 19 degrees as a decent range) and note the max boost at that timing and peak HP. Optionally pick two boost targets like 15lbs and 20-25lbs to give a range. We need a spread but we don't want to kill a mule before all the testing is done.
Then the final test is run your max timing at 20lbs and note the max timing and peak HP. This last test is the same as the first but I've put it last because this might be the one that breaks a test mule. :)
That should provide some interesting data points across fuel octane, compression, boost and timing. It's a lot of work to run all those tests though. :)
My testing has shown compression wins every time
👍🏻👍🏻👍🏻
That’s what I wanna see
That’s what me and my buddy argue about he runs 8.0 and I run 10.5
I say it makes it more responsive and you don’t need as much boost to get where you wanna be ...he says physics boost is boost 🤷🏻♂️
Would definitely love to see some real world testing on this one 👍🏻
I enjoy your work and videos, but I have noticed you like E85. You should try our 85 - 88 oct. MON pump fuel. :D
So how well do 862/706 heads work on 6 liter bottom ends?
@@turbolq4 just keep the 317s and run a .027 thick head gasket and you'll bump up your compression and have better flowing heads. The difference in flow isn't huge on a 5.3 but it is definitely noticable with a 6.0.
@sloppy mechanics 😎 it's that area under the curve h8torade.
Class is in session, quarantine won’t stop our learning.
Turbo test. GT45 vs VSR 7875 vs S475.
Having lower compression gives room for more horsepower with higher boost and timing when knock limited. The VE loss going 9,5:1 to 8:1 is diminished. But this is only works under full load and full boost. Which makes drivability and boost lag a bigger concern with low compression.
So it is wiser to compare torque curves rather than peak power, like always
This guy went with high compression ratio and the heads lifted as a matter of course. Then rebuild the engine with more boost friendly compression ratio. Here the test drive en what he thinks about the new "lowcomp" setup. This is typical :) :
ua-cam.com/video/fNjAb8Ac6hU/v-deo.html
That's good point alot of us are limited to used pump fuel cause of our were we live. Like to see low compression setup done on 87 or 89 octane something average person could street in there truck or car.
I would like to think that it all revolves around peak cylinder pressure and the point of occurrence in the cycle. If 91 is the octane limit, I'd rather go with more compression and less boost. Size the turbo to be very responsive and have low backpressure to get good midrange and area under the curve. Probably pull timing around torque peak and add back in around hp peak. Probably not skimp on the intercooler to keep the IAT under 100F. I just think that lower compression and more boost will be sluggish on the bottom and ultimately have less area under the curve, but higher peak numbers. Just my opinion until Richard Holdner tests and breaks down the data😎
I don't understand. I get not being able to rely on a knock sensor on an engine dyno. But how do you tune engines for optimal power?? You must have some method of dialing in the ignition timing, no?If you figure it out I'd like to see what 87, 91 and 93 would do with boost. Ideally you'd compare compression ratios, boost levels but also cams because certain cams are going to spike cylinder pressure at lower RPMs and really cause issues. So can you tune around it? Pick a few engine combinations and then run an optimized dyno run on 87, 91 and 93 and let's see what the curves look like. How much timing did you have to pull out and where is the line for switching to higher octane? Actually, you probably should throw race octane levels (or just E85) into the mix as a baseline. A lot of work but done right could be VERY interesting.
Need to test quad IDA-48mm down draft webers😁. Or quad 55mm-sidedraft Weber😁.
With big cam and lots of compression.
no
Yes! PLEASE do a test with some lower octane fuels for those of us poor people that can't get good fuel in our neck of the woods!
The closest place I can get anything better than 91 octane is like 3 states away... same for E-85. I know there are a lot of guys running-around that are power-limited by octane, who would love to know how to optimize.
High compression and low boost will be an amazing street motor. Low compression will allow more volume for higher boost, but it will be super sluggish because not enough exhaust energy is made to get it up on boost while it’s under the curve.
From all the street engines we've built this holds 100% true. If you use good fuel and with a good tune there is no issue mixing boost and compression. This is actually beneficial for a street engine because the compression helps with power when you are not in boost and many times on the street you aren't cruising around in boost.
@@kennethpowers8995 What's good fuel?
@@bartpang I was using the term loosely just to describe something with a high octane rating. Simply put the higher a fuels octane rating the more resistant it will be to preignition/detonation so you can get more aggressive with your tune on higher octane fuel without running Into problems. E85 is so popular because it typically has an R+M/2 octane rating of 108-110 in most cases but costs about the Same at the pump as premium gasoline 91-93 octane. The downside to this is that you use significantly more ethanol than gasoline per volume for a given setup, so your fuel system needs to be able to flow larger amounts and in a street car your overall mileage will suffer on E85 vs gasoline, however you can typically see nice power gains when tuning on E85. This isn't to say you can't run a boosted or higher compression engine on regular 87 because you absolutely can, however you will have to pull significant power from your tune in order to keep it safe. We have seen some success with quality additives as well such as "Race Gas" (Brand) which can be added to pump gasoline to bring the octane points up quite a bit and when mixed properly it does work very well. For an example today we have an import on our rollers, a B20Vtec Honda @12.5:1 compression breathing through a GTX3076R turbo. This setup just made 446whp on a content of about 77% ethanol as per the sensor reading and we have seen zero knock count at this power level thus far. This is an 84mm bore x 89mm stroke 2.0L inline 4 cylinder with a stock port head, stock crank and just some off the shelf pistons and rods with ARP hardware. Very basic and steerable import setup with quite dated engine technology.
@@bartpang In race only setups there are a lot of good fuel choices as well. For instance methanol fuels such as VP M5 etc have a cooling effect besides detonation resistance so many people do not even run an intercooler on boosted methanol setups to save weight and still do not see any negative detonation issues due to high IATs with no cooler. There are also a plethora of oxygenated race fuels which make power over standard pump fuels because of their composition and how you can tune because of it.
That's getting away from what the topic is about which is boost on pump gas.
That’s an interesting test. Compression vs boost vs octane. A tuff motor on pump is more useful then one that only runs race gas. Well unless it’s a full track car.
Consider the following formula: Compression X Absolute Pressure. I do not think the fuel would have any idea how the cylinder pressure is generated. If knock limited at 11:1 NA you would have the same cylinder pressure at 9:1 with about 3.2 psi boost.
I saw a video on compression ratios and cam profiles where this was the very discussion. It boils down to any given fuel will detonate at a particular pressure, the demonstration was 11:1 advertised compression and the old L9 cam. Both service manuals noted a cylinder pressure of 150psi. The L9 cam achieved this by bleeding off pressure gained by having 11:1 ratio compared to earlier 8-9:1.
Man, you always rock the tests. I really appreciate all the info. Even stuff I wasnt aware of. Learning every day. Thanks. Btw.... you sling them hands around. You be you, my bro. Dont let anyone change you. Thanks
Richard, you mentioned running your non-intercooled Mustang on 87 for routine commuting, and higher octane for competition-maybe I’m reading something into your comment. However, with the compression ratio question, longer duration cams that give the strong mid-range and top end power will kill the low end. The part throttle, low rpm part of the chart, never seen on full throttle dyno runs, will suffer. David Vizard’s answer, as I recall, was to increase compression ratio to get much of that back. In a turbocharged engine driven on the street, this guidance would seem to apply. I’d suggest as much compression ratio as you can reasonably get and limited boost for routine driving, and E85 when you want/need to turn it up. Water-meth injection probably has a place here, too. One more question, though; my Harley uses something called ion detection for knock sensing. Do any factory or after-market V8 ignition systems read the ignition current wave form to detect knock? Seems like this would work on the dyno even with solid engine mounts.
The 706 does not make more power than the 317 only due to compression ratio, the ports are sized better in cross sectional area for the power level. if people think of cylinder heads as flow you miss the point entirely.
Advanced cam is never as good as the proper lobe centres
, the caveat is it depends a bit if the duration is excessive or not. the more excessive duration the more the advancing helps bottom end without hurting the top.
Test this intake racehead.com.au/product/ls3-itb-kit-rectangle-port-carbon-scoop-plenum/
You're gonna need to send that to him lol. But he's already tested ITB intakes on LSx engines.....
For the first three minutes, I'm thinking Richard's been in the super glue. HANDS HOLDENER!!!
Wow sounds like some great videos coming up. I'd like to see the new Edelbrock Cross-Ram tested with twin turbos.
Richard what about rubber engine mount and driveshaft guebo/giebo/flex joint between dynometer and flywheel
Add a fluid dampener and I think you got it!
@warpigolet
fluid dampener will cancel engine harmonics. The issue is NVH from dynometer not engine itself.
@@RadRidesByCru In my mechatronic point of view if it can't be solved in simply mechanical way. we should use electronic.
Just install knock sensor on the engine as always plus add the same sensor on dynometer to record vibration caused by this device. You overlay recording from the engine and measuring device and that way you filter your signal cutting noise and clean knock signal is sent than to ECU
@@RadRidesByCru taht way i fully agree with you.
It's static compression ratio VS. effective compression ratio
Interested in the compression/ boost theory your on to something and I’d love to know
Can we get a video on the square body in the background??
My opinion:
The higher compression / lower boost combo is going to out perform the opposite combo with lower compression / higher boost.
It is going to make more power out of boost, be more responsive and likely make the same power at peak boost, as the opposite scenario.
But I'd still like to see what You find.
Off-boost the moderately-higher compression engine wins. On boost, at the detonation threshold for pump gas, the moderately lower compression engine will prevail. I wish we could wager on it.
It’s been proven by the likes of Gale Banks and other pioneers years ago that lower compression and higher boost with more timing makes more power till fuel threshold is reached , high compression and high boost works with Methanol not e85
Chilly Willy I agree. The efficiency of an engine is directly related to the CR so maximizing it for any given power level should be the best you can do. Get it as close to detonation as possible.
Marc and Josh. I’m assuming that we are talking about making the same power level both ways as opposed to which way has the most power potential.
@@marcstlaurent3719 sounds like a guy still running a carburetor, time to embrace the new century grandpa
I think the best method to test this is on a chassis dyno, my personal opinion, is that lower compression will offer greater flexibility, as you can always turn the boost up, but if your compression ratio is high enough, you can run into detonation with no boost. That being said, I think the best bet is probably around 9.5-10:1 range.
Adding boost is adding compression dynamically. There 8s a mathematical equation for this using Nitrous. It's the same for boost. If you have higher or lower compression dosent change anything other than the starting point. How efficient your combustion chamber is will play the largest factor at any level of compression or boost.
How about a test with just regular, 87 octane?
Richard, in the process of building my car. It's a 1980 Pontiac Sunbird all steel car even the hood but, all mild steel round tube chassis. I always watch your videos as you tell it like it is. Well anyway I have all the internals for a 403 stroker. Pistons are Wisco 8.5 cr 4.005 bore. I'm a believer of the low compression high boots cword. I'll keep you posted on how it goes.
I have see alot of the testing on the intakes. I not see a stock ls2 intake test. All I find is the dorman ls2.
Just a thought, the msd intake, and possibly porting some of those aftermarket intakes. Just a thought. Great oversights on those videos as well.
I would think when octane is an issue the lower compression would be better. I think you could get more gains out of say 3psi of boost vs 1/2ish point of compression. I don't think it is a 1 for 1 give and take. like you give up 30hp in compression and all you can get is 30hp in boost. You might be able to get 60hp in boost. Everything else being the same of course. But you're the expert. I have learned so much in the last few weeks watching your videos than I ever thought I knew.
Compression is a great way to make an engine more powerful, for the naturally aspirated guys it's a no brainer! But with extra cylinder pressure comes less margin of error available in the tune. Again, this is fine for the n/a guys that have the ability to properly tune even on pump gas run 12.5:1 it's great!
Now with boost your changing the entire game, cylinder pressure brings efficiency so you don't really have to work so hard to increase the efficiency of your combustion with compression when you have boost. The standard 9.x:1 compression is perfect for the average guy to keep sustainable cylinder pressure while doubling their output on some of the worst fuel available. Which brings me to my next point.
The faster a fuel burns the less power you can make with it and the regular unleaded is about the worst. Anything that gets pressurised burns much faster and of course the higher the pressure the faster the burn. You have different cylinder pressure limitations for different fuels for this reason. Basically the higher your cylinder pressure is the less ignition timing advance you can run. You can only retard timing so far before your not gonna make power anymore.
So if you wanna make a lq9 with 706 heads you got almost 12:1 compression. You could probably make 750-850 crank hp on the Dyno on low boost on premium pump gas with a big turbo but after that your done unless you go to a different fuel. Now put the stock 317 heads back on it for that 10.2:1 compression and your gonna see 1000hp safely on pump gas with the same setup and way different tune and more boost (my dyno numbers are hypothetical). Engine will probably rev out a little better on top too with the bigger intake valves of the 317s.
Just gotta understand the science to know what parts combination is going to meet your goal the most accurately.
BTR LS3 equalizer versus Holley EFI high-rise LS3 race intake
Right on time richard thanks for my drive to work knowledge
congrats on pole position
@@richardholdener1727 lol i give the credit to youtube for a quick notification
With a professional knock detection you can run the engine on the dyno with low timing and high octane and plot out the freq threshold of the setup on the dyno and then you will start raising timing and see when the knock sensor will detect the ping that is higher than the threshold you measured before .
Offcorse this is all theory till somebody try it on the dyno.
Good luck love your videos 💪❤🔥
@Paul Schwartz My built LS with aggressive cam and loose gapped internals doesn't trigger the factory knock sensor in the vehicle. I suspect it's something in the dyno room setup.
@Paul Schwartz yes offcorse my friend you are 100% correct. I talking about the AFTERMARKET solutions and he is not using factory stuff anyways
@Paul Schwartz That totally makes sense to me ... Solid motor mounts are going to transfer a lot more, and the tapping on the exhaust manifolds is a very similar frequency band! You're definitely right that lots of things can cause false knock. In my case the cam and forged loose gapped internals just don't do it (lucky me) but I do also have a relatively stock vehicle in terms of transmission, mounts, etc.
I think the most important thing to consider concerning the compression of a boost motor is how forgiving it is when it comes to the tune up, fuel inconsistencies, etc. A motor that's on the edge isn't a good idea for 99% of people.
J-Tec Blowby meter. Superflow sells them with most Dyno's these days. Then with an I/O in the holly setup, configure the knock module for a given voltage. Of course it would take few light pulls on low timing to get a base, and Unfortunately every engine would be different, BUT, you would have knock detection free of sound. Many racers are using a map sensor for this and pressure sensors in the coolant reservoir too. Lastly, You could point a camera at the exhaust. If you see black smoke you knew it detonated. The bad thing about that is coordinating time/Rpm to know exact data points, but you can go by ear too for a low budget alternative.
I'm surprised J&S couldn't tune the background noise out of the knock setup he builds. Must be REALLY noisy in that dyno cell, lol.
I use his interceptor setup and love it. I just tuned the sensitivity til the normal noises my car makes quit triggering the retard and its gtg. Lots of confidence when you run pump gas / water-meth. Bad gas , bad weather conditions, emptied meth reserve , etc isn't going to kill my engine . 10* dropped out instantly when the sensors are triggered puts my timing table in a very safe zone for almost any situation. I use the innovate scg1 boost controller too. That pulls all the boost back to wastegate if my afr leans out . The combination of the 2 systems is something I'd recommend to anyone who hates pulling engines ! Can it cost me a race ? Very possibly . 10* zapps a lot of power. So does a drop in boost from 16lbs to 8lbs. Id gladly loose a race to keep my pistons , headgaskets, and rods where they are suppose to be , lol.
Richard, I'd love to see a test on compression vs boost on pump gas. Lots of guys in areas like me without easy access to E85 would appreciate it , I guarantee.
I know this is an older video but have you tried something such as the PLEX knock monitor? You baseline it for normal frequency then induce knock intentionally to distinguish the difference. Looks like version 2 was discontinued but v3 is on its way.
It's something I'd like to play with on some circle track carbureted stuff. Get fuel distribution best as possible, then use an LS style ignition (can be for dyno purposes and have an end application to make sense cost wise) and get individual cylinders tuned and transfer that to an adjustable distributor rotor. Get a motec dash and take everything to the track to test and tune. Then pull it to be legal and use DA/ADR...
Would be more useful on turbo applications but not exactly realistic for most DIY
Thanks for the content 👍
I WOULD LOVE TO SEE THE BTR Cathedral port MANIFOLDS VS some of the higher-end intakes ....
Equalizer vs High Ram vs Pro Flow boosted would be nice....
Richard Holdener have you done anything with the VVT? I'm fixing to put a 4.8 VVT-non DOD into my 69 Chevelle. First LS for me. Should I keep the VVT system or delete it? I'm on a tight budget, but I would eventually like to install a performance camshaft in it. My car has been parked for nearly 20 years. Time to pull it out of the weeds!
On Knock limited fuel. As long as the adiabatic efficiency isn't compromised (by going off the map), and you're not out flowing a turbine side... You'll always make more power with more fuel, less compression and more boost.
Few reasons. The primary cooling of a cylinder is actually the air and fuel entering the cylinder.
More O2 density than not...
And having a VARIABLE compression (ignition timing) gives you more resolution to dial that in.
Richard, here is how the top tier car manufacturers are sensing detonation now. Shoud be the answer to your problem: www.pistonheads.com/news/ph-explains/what-is-ion-sensing-knock-detection-ph-explains/38892
I think you can run more boost, safety. But it will create more heat, obviously.
So you’d have to compensate with the intercooling. Maybe run water to air on turbo applications and water pump volume…obviously on a standalone system
Are any of the ion knock detection systems available in the aftermarket ? I know oem are using it. I thought I heard maybe haltech had a unit for their system
Not that I am aware of I have searched hi and low for this system it would be really nice to have that for per cylinder correction
In the end it’s still all a mathematical equation and what you plan to do with your set up. If your gona only run 91-93 oct and 10-14lbs of boost. Why run the 706. Your not looking for that power level. Why push the tuning threshold just throw 317’s on it and be safe and have fun. If you lookin to run race fuel and make 20lbs of boost and your looking for every hp you can get do the higher compression head and run a race fuel. Me personally. I want all I can get out of my set up. My engine going in my car is 11-1 comp. I’m gona run E90 and I’m gona put 20+lbs of boost threw it and I ported my heads and all the supporting mods. If you looking to street drive and only run 93 oct. why go for the higher compression You’ll never feel the difference of 50-100 hp by adding more boost and timing and all that. It’s more of a question what’s your plan with the combo. Full race or daily fun driver.
What I wanna see is difference between 87 and 93 octane - what you can get away with. E85 and race fuel is cool, but I'm more interested in what works for a daily driver. Price difference between 87 and 93 is too big for me to ignore. And yes, please, more M90 :) Maybe it needs to be tested on a turd like 5.2l magnum?
Richard Holdener Have you come across the www.plex-tuning.com/products/plex-knock-monitor/ It's supposed to ver good and configurable
Here's a thought: I don't have dyno numbers but a 5.3 with a stage 3 truck cam, 6psi, and 88 octane has been dependable so far. I never tried higher than 6psi on gas. I have pushed 15 on e85 though, on the same engine.
Comp ratio is not as much a problem as lack of quench imo... in the old days of my 351 Cleveland I had with open chamber heads that engine wouldn’t take as much timing on 91 as the closed chambers heads with more compression ( and bear in mind that in Australia our 91 is like 87 octane.) before knock would set in.. Obviously it’s not the compression ratio that was the problem..
Richard, to use knock sensor control effectively you will need to use an ECU with a more advanced knock control, like a Motec.
The Holley stuff is good, but not when it comes to using knock control. ...and the difference isn't even close.
BTR equalizer vs its competitors (hi-ram, proflo etc..)...everyone has been waiting for some actual numbers!!
Step up to a Kistler in-cylinder pressure transducer.
Shave the 317 heads to have the same compression ratio as the 706. I still don't think they'll match them on a 4.8/5.3.
I wonder about the knock sensor problem, can it be filtered like mount it through different metal? like an aluminum block to help filter the extra noise ... feed the knock sensor into an audio input and use a computer to 'see' the spectrum is what I did with a f150 4.9L I6.
Direct cylinder pressure testing equipment will tell you for sure if it's knocking. Best way to know on the engine dyno. Knock sensors false activate on the chassis dyno as well. You have to calibrate them using individual cylinder pressure testing equipment. A good person to talk to about this would be Scott Clark at realtuners on facebook.
I can tell you for certain, it is not the trade it sounds like! The issue with a really low compression boosted engine is NOT that it cant be made to feel snappy, because it can, it just needs a lot more ignition timing to do that, and the timing pull into boost simply has to be based off that "na" timing, What is wrong with that strategy is that there's much more time for bad combustion events. The higher compression engine wont need as much timing to make the same power. The detonation limits for both have a lot more to do with "continous boost" versus intermittent boost. At 6.5:1 cr, you can probably run close to 40-45psi continuously at best timing, but when the cr goes up, the boost better be coming down or not be in it as long. I've heard of guys going out to 30psi on pump gas at 9:1, but the timing to do that was zero degrees. The real trades on high compression/ low boost versus low compression high boost have a lot more to do with the exhaust gas temps... the higher the compression is, the lower the exhaust temps are, so the turbo would likely need a smaller exhaust turbine to spin at the same rate as the lower compression engine does, all else being equal. In fact a great way to "equalize" the 2 combinations would be to go for the same exhaust temperature, and creep the timing up at a fixed boost level... I guarantee you, when you are too close to blowing it up, the exhaust temps start falling, and the engine starts loosing power, at the same boost level.
In the dyno cell you should put knock sensors everywhere you suspect there is the same knock frequency. Next you should both find a correlation, or eliminate, sources of that same frequency
Have you thought about testing a Shelby GT500 blower ? They are super cheap and I think you can use just a flat plate for an adapter . I been looking at some on EBay
You know, I think one of the most valuable things you're providing here Richard is that you're teaching people to have a model of how turbocharging behaves with an engine, how cams behave, heads, etc. Now detonation and octane is one thing that there's plenty of information out there on, but I still have yet to find a succinct explanation that gives the same sort of quick instinctual understanding that for example your "hp=NA HPxPressure ratio" model provides. So maybe dive into tuning some, and play around with 87 octane or something just to stress the system. Take a turbo LS, say you run 10lbs on 91, then do a 87 tune on at that same boost. Obviously the 87 will be less, but can you just add more boost and run 87 with conservative timing and fueling? Street cars aren't class limited like race cars, there's no restrictor plate governing how big we can make our turbo. How much worse is it? I guess that's the question, how much does octane really affect the ability to add timing. Is it that you can run 25 degrees vs 20? Or is it that you can run 25 degrees vs like 5, or less? Can you even push 10lbs into an LS on 87 octane? Do EGTs get dangerous when running extremely conservative timing?
A bigger problem on the street is what works with a 100 manifold temp can detonate at 120. So you could make one pass at the track, shut off for 15 minutes in the staging lanes break pistons on the second run because everything is heat soaked.
Much agreed. Always excellent content.👍I'd like to see low comp. High boost vs high comp, low boost. Along with 87 compared to 91-93 octane tune. I think a lot of us would give up a few hp in order to run regular 87 pump gas. Would make some interesting testing, just saying.
It takes are air and fuel to build power. Simply put if you run high comp pistons your filling the applicable space with metal from the pistons, thus reducing the amount of air and fuel you can put into the cylinder. I mean look at top fuel engines they actually use a really low compression pistons. That gives them more room for air and fuel. But now remember key word in all this is (91 octane) not max power at the strip.
Nix the idea of using the Northstar integrated blower manifold with the Laminova tube intercooler. The intercooler is lousy. Low effectiveness and high pressure drop. I did a lot of testing on Laminova tube intercoolers when I worked at Eaton in the aughts, and they were far outperformed by brazed bar and plate or tube and fin types.
For snappy engine feel 10-1 is fine for pump on boost look at the new mustangs/camaros I think they are 11-1 and up running pump gas making 700+ on pump the only time I would see running low compression is if you have no boost control or plan on 1000+ hp for pump 10-1 in my opinion is great also talk to your tuner and ask before you build what they are comfortable tuning and set ups they have seen be successful also remember more boost is hotter air sometimes it’s better to have a snappy engine with compression and less boost making great power thru efficiency then boosting it higher to make up for compression and not being faster due to heat
My old 95 Mustang GT with RHS 180 heads, I ran 13lbs of boost with my Vortech and 22 degrees of timing non intercooled with no issues. Made 453 to the tire.
Lower compression will allow more timing for more power sometimes. You have to build the head smooth enough to not have hot spots which are magnified by the higher temperatures. More easy to increase compression for power in lower air flow, street, set ups. But we will all dream of perfect engines.
Personally I blame squirrels
My beaters got more gutless and less responsive off boost with low compression but about the same once the turbo spooled up with pump gas. Seems like i got away with more with big cams, but that also made the low comp motor even doggyer before boost and idel worse
I have put a turbo on a stock LS1 (10:1cr) a stock 4.8 and 6.0 both (9.5:1) a 5.3 with 317 heads to drop comp to (8.8:1ish) and I built a 370ci with dished pistons (8.5:1) .Out of all those engines the LS1 made the same power (within a couple numbers) of them all on the least amount of boost. So it proves the better NA the better under boost. And the LS1 sounded much less like it was going to blast off into space doing so.
I'm gonna say lower compression with more boost is gonna make the most power being octane limited. I guarantee that a 7:1 motor would make gobs more power than say a 12:1 motor on low octane and taken all the way to detonation. Downside is that the low octane motor will be very lazy outside of boost.
Get adapters and run a ls7 intake on the smaller ls3/sq port heads and see if it gains anything..
Dropping compression will make a engine a complete dog out of boost on the street..
Not being able to test with a knock sensor does make that pretty difficult. When I asked this question it was more about being able to use boost with crappy fuel. In Australia the guaranteed available fuel has a rating of 91RON. the equivalent US fuel grade 87~88. Australian 98RON is only US fuel grade 93. The US fuel grades use an average between Ron and Mon to better describe the fuels resistance to knock. I know the cam and flow restrictions plays a huge part of the achieved compression ratio so maybe just test with the standard cams and manifolds? Maybe a 4.8 and a 6 liter test stock and boosted with a plot that at a certain set boost level say 5 lb increments just feeding in timing until detonation? Test this on the crappy fuels and maybe just look for the detonation in the power output? Basically I'm trying to decide on compression ratio wanting to use crappy fuel with boost. My L98 runs a pretty high compression ratio to begin with with a 10.4 to 1.
Anyway I know I should just bolt it together and see but now is kind of the time to replace the pistons if required. Droping the comp down to 9.5 will let it live on the crap fuel with good timing and spin up the turbo faster and any short coming from the low comp power wise could be easily masked with boost.
Just thinking out loud.
Keep em coming Richard these videos are a daily highlight.
I would like the pump gas test with compression vs boost and maybe just graph the knock sensors to just have as comparative data points
Isn't it just a function of cylinder pressure so the 1 psi extra gives the same cylinder pressure as the higher CR setup? Other factors then dictate where knock occurs (end gas, poor turbulence therefore mixture distribution, hot spots etc?).
I could be wrong but my theory is that one more pound of boost will contain more air density with the ability to burn more fuel and raises the compression stroke cylinder pressure to the higher compression ratio level yielding more power.
U should test a Frankenstein intake at least that's what I think its called it's the same intake that ruby has cleetus red Corvette. What's the power gain on a stock engine vs $. Is it worth it because it's not cheap at all.
Guys He said this before and it's TRUE. The more efficient your air pump is at making power, the better it will be when adding boost. I imagine he is doing this video to support his claim , just in a different way to draw you into what he is talking about. Doesn't matter what your starting point is on compression, boost is a dynamic compression adder. So if you change a variable in the equation, like adding efficiency to the combustion chamber, VIA find which head works best, now your making more power from optimization as opposed to arbitrary flow data.
I don't think he is leading us. So I half Agree with you, because You're quoting him. And he tested And showed us the Is results. But the thing is. He is talking about pump gas. And keeping it together, more so then max Possibilities. # you could run 30lbs with 12.1 compression. If you could get the IAC down super low and run E85 . 🤘
You would have to analyze the exhaust gas for presence of nox gas it starts showing iirc 6 to 10 degrees before audibly detectable of a conventional knock... sensor. Hope that helps
Lol what exactly is "NOX" gas? Havent seen that one on the periodic table. I kid, I kid, I know what you mean but this is more of a trade done with diesel engines not really ethanol setups. Hands down the best way to adjust timing without using audible knock sensors is spark plug reading. Do your pull to WOT, kill the engine before the revs even drop and then pull the plugs to read the timing marks.
From what i have seen oems do on subaru EJ platforms ,, more boost with slightly less compression in an engine with better flow characteristics is pushed to yield higher power levels.... while the more modest setup is less boost but with a few decimals higher compression, and longer runner intake, (less top end flow setup) smaller cams and smaller intercooler surface area and smaller volume of plumbing..... seems the latter is dialed for a bit more response and efficiency at the cost of top end power... and top end setup has a bit more buffer for detonation but more flow in system , both want premium gas.
Like it see this tested about to build a iron 5.7 and want to boost it down the road. Back and forth on which way to go with compression
Maybe manually check the nock whit a stethoscope? Seen some wizard do that on max speed runs
Alright I recently opened up my gen 3 5.3 and did some boost ready upgrades. With advertised 8.5cc stock dish pistons ( i personally CC'd mine and it was 7.5cc ) 799 heads 63.5cc 3.780 bore .050 LS9 head gaskets i was around 8:8.1 my goal is to get to 15 psi without needing methanol injection. I will keep everyone posted
What happens?
When you're octane limited with boost, lower compression is the way to go. We build, tune and chassis dyno many different modern domestic vehicles and 9-9.5:1 is the sweet spot for 91-93 octane. This allows 15ish psi with a wider tuning window and good reliability. This is also assuming you're after the biggest power number possible on low octane fuel. Some combinations may call for the lowest iat's possible such as a road race combination. Then lower boost is desired (8-10 psi) and 10.5-11:1 compression is the better way to go. Once you go e85 or race fuels then it's a whole different game. 10.5:1 is a good starting point for higher octanes and boost.
Matt, on a 9.6 compression gen 4 5.3 at 11 psi what timing do you get away with running on a carburated set up? Stage 2 turbo cam, I have 92 octane here but can mix if needed. I'm at 12 but I feel like I'm giving away some power?
@@jimcrawford4360 intercooled?
Not intercooled
it seems like the engineers at Chevy ford and dodge use lower compression engines with boost. So clearly it does offer some safety. But IMO compression is nothing but efficiency, and should not be forgotten even with boosted engines when it comes to hobbyists
I have been wondering what is the best trade off between compression ratio, boost, and ignition timing.
I tend to follow the “more power with less boost” line of thinking so I would choose the 706 heads for more compression with a lower boost level because that’s more efficient but I am curious how far that can go on pump gas.
I think Mr. Holdener, that the time has come to upgrade from the (admittedly very user friendly) Holley HP EFI to a more fully featured and capable ECU that has more advanced features. The obvious choice is the Motec M150 (because I'm an Aussie.) The Holley is pretty limited in its sensor pack and knock control strategy (as you've discovered here,) vs ecu's not targeted directly at the American V8's.
With the Motec (and other ECU's like the adaptronic M6000 I use,) you can 'gate' the knock signal vs. crank rotation so that the ECU will only look for knock at very specific crank angles (say between -35 BTDC to +5ATDC of each cylinder.) This means the ecu can reject a great deal of 'noise' which is occurring when there is no spark event. In addition you're able to adjust what frequency the ECU is listening for vs crank rotation. As knock at -30° and-10° may occur at different frequencies.
To the best of best of my knowledge the Holley ECU's don't have these advanced features.
Regards
Jordan
I'd hit Haltech up, those guys love publicity, and if it was getting used all the time, that would be good advertising for them...
@@DodgyBrothersEngineering Haltech isn't in the same league as Motec/Syvecs(Life.)
Unfortunately you're not really able to use the ecu's from nasvar/indy either, as their bespoke, despite their advance nature.
@@manitoublack I know Motec have been around a lot longer, but Haltech is no new kid on the block either. What can a Motec offer that a Haltech cant on the dyno? My 14 year old E11v2 I have sitting on the shelf is still a fairly advanced bit of kit, probably as advanced as the Holley.
@@DodgyBrothersEngineering Motec are leading the way with Torque demand electronic throttle mapping/tuning.
Basically your throttle position doesn't = a throttle-plate opening. But rather acts as a 'I want X-ammount of torque.' basically you can use a motec to play tunes with the throttle plate to make a high boost small engine behave itself. This also interacts with wastegate control to make power delivery far more linear instead of peaky.
Motec also have a developer sweet so you can write your own runtimes for specific requirements. And that's just scratching the surface. There is a reason motec (and Life) are found in rally and touring cars the world over. They're the best non-bespoke option.
Hey Richard, did I miss the links in the video or did you forget to add them (LOL). I'll find them.
Is detonation a function of CR/ boost, or simply the pressure inside a cylinder? I can't wait to find out! Looking forward to the advancing cam testing. Would it be possible to run VVT as a test? Awesome work, thank you!
Hey Richard, it seems to me years ago there was tests run, and they were using a Ford with vortech Blower, and they were comparing compression at 10 and 12 to 1. The higher compression made way more power.
higher compression makes more NA, so it makes more under boost if you have enough octane
If you don't have pump e85 in your area the best is to lower compression off course
The guys in NZ and Aussie would like to see some comparisons between the 5.7 ls1 and the rest, as this is the most common we got and I don’t know why you guys don’t seem to use them.the05 dbw 5.7 may even have gen4 rods, and I believe after 2000 the blocks and sleeves had improvement from factory.
The aluminum 5.7s cost more and even with the sleeves can't handle the power the cast blocks are capable of.
D. Ryan crikey all the boys down here are chucking a gt42 on them and they seem to make some crazy power but I believe you I got me a gen4 5.3 from you guys so this makes me happy
@@8wireracing694 yea they still make good power but it's not uncommon to run a 5.3 up to the point where they start pushing water. 1000+ hp
When it comes to boosting I have always advocated for 8.00~8.50 : 1 and cram that cylinder with as many air molecules as your engine's metal bits and pieces allow it to.
In fewer words: Low compression, high boost, conservative timing . . . and under hood real state permitting it, ALWAYS aftercooled. 😎👍🏻
What about the effect on low speed driveability and lag? It seems to me that a big block with 8.5 would be more forgiving on the street than a 4.8, especially in a heavier vehicle
@@travispfannmuller7717 life is full of compromises. Engines are no different.
The lower the boost, the worse the low end response will become unless you have an elaborated twin turbo system with a small one for low-mid and a big one for top end.
Or the other trick of turbo-supercharging. Screw blower for low-mid and big 🐌 for top end.
Personally I'm old school too. I prefer the BBC over the LSx/LTx platforms.
Too bad a BBC aluminum block and heads, even after all these years, STILL cost as much as a small apartment. 🙄😔👎
I have experienced with a GM square body dually powered by both a 350 and a 454 and for sure, even the smog choked underpowered 454 moved that Barge way easier than the healthier and snappier 350.
Also big bang a gen 3 truck motor with summit pro LS rods & pistons (might a swell go for more compression).
Max boost on pump gas on old style turbos is about 13 psi with an intercooler.
Richard, I would definitely like to see a test comparing compression ratios - I've got a 6.0 with dished pistons on an engine stand and I've been trying to decide if it's worth the expense and effort to put in flat tops that would raise my CR from 9.6:1 to 10.3:1. Maybe start with an NA comparison first b/c it's less likely to hurt parts, but in addition to varying the timing between the two engines also vary the fuel grade i.e. what's the best each can do on 87 and 91.
A higher compression would be a waste to run with low octane fuel. You’d be adding extra fuel and pulling timing to retard knock. You’ll probably pick up 30hp with higher compression pistons on 91 octane. But where it gets better is the torque curve and the throttle response will be 10x better.
I'd mostly be interested to see the 9.5:1 engine with 87 and optimized timing vs the 10.5:1 engine with 91 and optimized timing, but for the sake of comparison you may as well try it the other way around even if you think you already know what the results will be.
Because it will see boost in the future so I'd rather use LS9 MLS gaskets.
@@nowayjose596 if you're planning on running boost then buy a factory 6.0 shim gasket. All LS run MLS gaskets factory. Buy a shim gasket from like Tsp made for the 6.0 and it'll seal Better than one made for a 6.2.
Use a set of 862s or 706s. Check out the driveway engineer. He did a stock 6.0 and 862s and made decent power.
Hello! A quick question on the big bang motors, are you reusing original rod bolts when you regap the rings? Thanks
yes reuse
@@richardholdener1727 Thank you, and are you doing 15# plus 85 deg. or a set torque?
How good are 243 head compared to the heads in you video
Greg Gamer 799s are often used in place of 243s, for purposes of testing, they perform so close to identically as to make no difference. Check this link : www.lsenginediy.com/ultimate-ls-cathedral-port-cylinder-heads-guide/
Btr intake and new holley modular low ram. Very interested in the low compression high boost. High compression low boost debate. That would answer alot of questions
Just go ahead and throw a lsa blower in the mix just for comparison
Would like to see a test of the ported LS3 intake done by Gwautney.
I've always trusted the blowby gauge .. as soon as the ring package get unsettled you have stepped over the edge.
What’s the deal with that square body in the background? Would love to see a video on it