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I think its more a matter of how much the motor makes NA. No turbo is going to magically triple the NA HP per BAR. If the motors wimpy NA, its going to need a lot of boost. No way around that IMO. You won't more than double the NA power per bar no matter what you do. (aside from iced A2W setups skewing that a bit) So if you're at 400 crank NA... The most your making is 27 crank hp per pound. Twins... single... doesn't matter. If you need to make an additional 800HP to hit a 1200 HP goal, you'll need to run 30lbs to get there! And those are crank HP numbers! Only Richard Holdner uses those!
I thought Richards comment in 1 of the videos is interesting about best case is double NA power at 1 bar. This means that it doesnt matter if youre running a small or large thumper turbo, the best you do is double NA as long as both turbos can support the airflow. So now you size the turbo for intended boost level, max power level, and RPM range and thats basically it. What it also likely means is that many people over turbo their setups.
I thought Richards comment in 1 of the videos is interesting about best case is double NA power at 1 bar. This means that it doesnt matter if youre running a small or large thumper turbo, the best you do is double NA as long as both turbos can support the airflow. So now you size the turbo for intended boost level, max power level, and RPM range and thats basically it. What it also likely means is that many people over turbo their setups.
The way I understood it...
It means if a turbo was 100% efficient the most it could do is double the NA power per bar. None of them are 100% efficient. (aside from artificial atmosphere A2W units) The "thumpers" are just closer to that 100% efficiency island/number at big boost numbers. While the smaller units may struggle to be 60-70% efficient at "big boost". Its why you see the gains per pound peak early w smaller units, then they make less and less power per pound at higher boost levels.
While the big boys can continue to make the same high efficiency gains, even at "big boost".
Its why Richards tests annoy me so much. He never turns them up. His T4 VS T6 test this week was kind of infuriating. He said the T6 offers no gains over the T4 at "1000 hp levels" and that there's no reason for a T6 on a 4.8 5.3 "1000hp" build. Which is ridiculous! He ran 12lbs and is claiming 1000HP, but did so on a 6.0 with nice aftermarket heads heads. OF course the overlays look similar with no real gains on the T6, its only running 12lbs! He also used a 1.10 T6 and a 1.25 T4. IDK his 1000HP claims annoy me. Freiburgers F-bomb bad boy nelso built 400+ cube LS made damn near 1500hp on that engine dyno. It trapped 154...
Last edited by Forcefed86; Feb 2, 2021 at 11:32 AM.
It means if a turbo was 100% efficient the most it could do is double the NA power per bar. None of them are 100% efficient. (aside from artificial atmosphere A2W units) The "thumpers" are just closer to that 100% efficiency island/number at big boost numbers. While the smaller units may struggle to be 60-70% efficient at "big boost". Its why you see the gains per pound peak early w smaller units, then they make less and less power per pound at higher boost levels.
While the big boys can continue to make the same high efficiency gains, even at "big boost".
Its why Richards tests annoy me so much. He never turns them up. His last T4 VS T6 test was kind of infuriating. He said the T6 offers no gains over the T4 at "1000 hp levels" and that theres no reason for a T6 on a 4.8 5.3 "1000hp" build. Which is ridiculous!
I agree that the larger turbos are more efficient at higher boost, but down at 1 bar or less, the gain difference in a 70% efficient turbo vs. a 90% efficient turbo likely isn't enough to justify the larger turbo unless your plans are to turn it way up. Everyone running around with 88mm turbos running 15-20 psi likely are sacrificing spool/part throttle/etc. unless they have large c.i. R.H. tests usually annoy me as well because the test is typically either inherently biased or had he gone 1 extra step it would have been more of an apples to apples comparison. #INB4STEVIETURBOYELLSATUS!
From the small 1.10 T4 S475 to the T6 S480 it cut back pressure almost in half. 2.6:1 VS 1.4:1. Also the S480 trapped about 5 mph higher on less boost. Pretty significant gains. Not a prefect comparison with the different compressors and all, but still very notable difference in BP. The Small S475 seemed like it fell offline around 18lbs and was pretty much done by 20ish, making very little MPH gains. I believe I got 1mph going from 22 to 26. Was really no reason to push it that hard, Just wanted my 8 second pass. Either way, the T4 S475 is in no way a good match for a 1000HP engine IMO.
I think your key phase there is 1000hp engine. The T4 S475 is rated at like 105lb/min so that would roughly be maxing the turbo if the cfm x 10 rule of thumb is close.
I think its more a matter of how much the motor makes NA. No turbo is going to magically triple the NA HP per BAR. If the motors wimpy NA, its going to need a lot of boost. No way around that IMO. You won't more than double the NA power per bar no matter what you do. (aside from iced A2W setups skewing that a bit) So if you're at 400 crank NA... The most your making is 27 crank hp per pound. Twins... single... doesn't matter. If you need to make an additional 800HP to hit a 1200 HP goal, you'll need to run 30lbs to get there! And those are crank HP numbers! Only Richard Holdner uses those!
Cant say I've seen that to be true in practice, and I'd say there's a lot more to it then just what the engine makes NA. Being in the efficiency range of the turbo, cam/valve events, fuel/timing, backpressure, etc all play into how the setup reacts.
I've gone from a turbo setup that's gained 30 hp/lb to one/ones making 50 hp/lb on the same dyno and drastically more MPH at the track. If what you're saying is true that simply wouldn't happen, or the 5.3L magically picked up 200hp NA overnight while it was sleeping For instance a setup that is maxing out a 75mm turbine and has poor hp/lb, you slap a 112mm turbine on it to solve the problem, its going to gain power letting it breath, and you can run more timing with less backpressure so overall the setup performs better.
Freiburgers F-bomb bad boy nelso built 400+ cube LS made damn near 1500hp on that engine dyno. It trapped 154...
BAHAHAHAHAHHAHAHAHA OMG did it also weigh 5,500lbs?
Granted we see this all the time, people claim 1200-1800hp on instafail, even seen tuners post calculated HP numbers, not even whp... come to the track and runs like it has maybe 900hp then the excuses start.
Cant say I've seen that to be true in practice, and I'd say there's a lot more to it then just what the engine makes NA. Being in the efficiency range of the turbo, cam/valve events, fuel/timing, backpressure, etc all play into how the setup reacts.
I've gone from a turbo setup that's gained 30 hp/lb to one/ones making 50 hp/lb on the same dyno and drastically more MPH at the track. If what you're saying is true that simply wouldn't happen, or the 5.3L magically picked up 200hp NA overnight while it was sleeping For instance a setup that is maxing out a 75mm turbine and has poor hp/lb, you slap a 112mm turbine on it to solve the problem, its going to gain power letting it breath, and you can run more timing with less backpressure so overall the setup performs better.
It's physics, no way around it. Best you can do at 1 atmosphere is double the density. They best doubling the density can do is double the power. It just goes to show how inefficient most setups are compared to a big honkin single or decent sized twins! The only way you can more than double the HP per atmosphere is if you have some artificial form charge cooling that brings you below ambient. I think the big disconnect is the chassis dyno VS Engine dyno. Dynos are BS plain and simple IMO. Use them to dial in the tune and that's about it.
It's physics, no way around it. Best you can do at 1 atmosphere is double the density. They best doubling the density can do is double the power. It just goes to show how inefficient most setups are compared to a big honkin single or decent sized twins! The only way you can more than double the HP per atmosphere is if you have some artificial form charge cooling that brings you below ambient. I think the big disconnect is the chassis dyno VS Engine dyno. Dynos are BS plain and simple IMO. Use them to dial in the tune and that's about it.
Agree a lot of setups arent very efficient, but it gets interesting when some NA engines get over 100% VE. Chalk it up to dynos being BS, but its odd when a 650hp engine dyno turns 1200whp on the chassis dyno on 1 bar. As long as it backs it up I could care less what the number is, I've seen 650hp trap 150 which beats claiming 1500 to trap 4 MPH more
Actually he just posted a video of the dyno run just now. 1154hp @27psi.
Originally Posted by Forcefed86
Thats pretty darn good for a $1050 single and mild 5.3 on original head castings/ports IMO.
I would like to compare the spool/powerband to a 88 or 94mm that puts out the same power. The cast version appeals to me a bit more at $850 or even less on sale especially at 38lbs, but I haven't seen where it out performs a pair of cheap cast 7875's.
If someone's already setup for a single, they seem worth a try IMO. I Agree though, hard to beat twins these days.
We have a local named Ryan Mitchell that basically just takes everyone's money here. (all over the mid west really) Runs VSR S480s on a basic non-intercooled BBC. Gaps cars with 5x the money in them.
If someone's already setup for a single, they seem worth a try IMO. I Agree though, hard to beat twins these days.
We have a local named Ryan Mitchell that basically just takes everyone's money here. (all over the mid west really) Runs VSR S480s on a basic non-intercooled BBC. Gaps cars with 5x the money in them.
I would like to compare the spool/powerband to a 88 or 94mm that puts out the same power. The cast version appeals to me a bit more at $850 or even less on sale especially at 38lbs, but I haven't seen where it out performs a pair of cheap cast 7875's.
The red mustang on his channel went from the vs80 1026hp psi wasn't listed but the with flashing lights should account for a couple extra HP, to the vs92 1175hp @ 35psi.
If someone's already setup for a single, they seem worth a try IMO. I Agree though, hard to beat twins these days.
We have a local named Ryan Mitchell that basically just takes everyone's money here. (all over the mid west really) Runs VSR S480s on a basic non-intercooled BBC. Gaps cars with 5x the money in them.
The red mustang on his channel went from the vs80 1026hp psi wasn't listed but the with flashing lights should account for a couple extra HP, to the vs92 1175hp @ 35psi.
Thats almost exactly what we got out of the VS 80, 1025hp before adding more boost was basically adding zero power. Those VS 92 numbers match up well to what we saw with an S491 with 1180 as well on same 35-36psi.
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For instance a setup that is maxing out a 75mm turbine and has poor hp/lb, you slap a 112mm turbine on it to solve the problem, its going to gain power letting it breath, and you can run more timing with less backpressure so overall the setup performs better. 
