Smaller turbo sizes
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On The Tree
Joined: Feb 2019
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Smaller turbo sizes Does anyone have any experience with using a smaller turbo for maximum spool time , street car.
just put in a th400 , 4200lb car.
going on a 6litre , l76 , 862 heads
im thinking a small cam with very little overlap will be needed with the higher backpressures of the smaller turbine.
thinking something along the lines of 10psi hopefully getting close to 700flywheel hp
s475 with a 0.9 a/r turbine
or a s300 s369 0.9ar turbine ?
maybe a btr stage 1 turbo cam , or even a cam motion reverse split ?
going with a 3.23 rear gear
just put in a th400 , 4200lb car.
going on a 6litre , l76 , 862 heads
im thinking a small cam with very little overlap will be needed with the higher backpressures of the smaller turbine.
thinking something along the lines of 10psi hopefully getting close to 700flywheel hp
s475 with a 0.9 a/r turbine
or a s300 s369 0.9ar turbine ?
maybe a btr stage 1 turbo cam , or even a cam motion reverse split ?
going with a 3.23 rear gear
Any Stage 1 Turbo cam and I'd suggest a Billet 7875 of some type either VS Racing or spend the coin on a Precision unit.
I think @GAMEOVA runs a PTE 7675 on a 6.0L iirc and makes like 700whp and 1,000wtq through a TH400 and it spools really fast.
Now if you ever want to make more power the T4 flange on that setup is going to limit you and you'll need to change the setup over to a T6.
Or just go with a T6 if you have the space, @RonSSNova runs a T6 with a smaller AR that seems to spool quick and makes enough power to put him in the 8's on a foot brake.
I think @GAMEOVA runs a PTE 7675 on a 6.0L iirc and makes like 700whp and 1,000wtq through a TH400 and it spools really fast.
Now if you ever want to make more power the T4 flange on that setup is going to limit you and you'll need to change the setup over to a T6.
Or just go with a T6 if you have the space, @RonSSNova runs a T6 with a smaller AR that seems to spool quick and makes enough power to put him in the 8's on a foot brake.
I've made over 1200hp with a T4 on a 6.0...with the right supporting hardware. If you want to be able to use an overall smaller turbo to keep the responsiveness up, even the smallest 'turbo cam' is far too large.
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The 7875 doesn't spool as fast as everyone thinks.
A billet Borg Warner in T4 with a max compressor of 75mm would spool faster than a 7875. A billet S369 in a 1.10 T4 would spool crazy quick in a 6.0 and a mild cam with sub 220/220 duration and still make 500 at the wheels on pump gas.
A billet Borg Warner in T4 with a max compressor of 75mm would spool faster than a 7875. A billet S369 in a 1.10 T4 would spool crazy quick in a 6.0 and a mild cam with sub 220/220 duration and still make 500 at the wheels on pump gas.
Your basically doing what I’m doing but I’m doing it with a 5.3. Cam, cleaned up stock heads, blower cam (between a stage 1 and 2 cam) NNBS intake. I have a 2400 stall (3k flash) converter and a small efficient 2004R with 3.55 gears with a 28” drag radial.
a cast and billet 78/75 turbo started to see 100kpa at 3k and full boost by 4500k which was 13psi. I ran a 76/65 cast .84ar for a hot sec but no info as it was short and jumped around trying ti figure out boost issues. I just pulled my billet 10 blade 78/75 for the new Next Gen billet 70/70 from VS racing. He told me it would be done around 800hp but I should
see 500rpm sooner spool on my combo. I’m hoping it works out great for me as I’m only street and getting into boost sooner would be a lot more fun and I don’t need more than 700hp or spin higher than 6500. On the 6.0 the exhaust side is a bit small but I could see u still spinning to 6000 maybe and would be even more responsive. I think a billet 69/73 borg copy from VS in thr .9ar would be a nice fit and offer a bit more flow but still spool really fast on a 6.0. That turbo should meet your power goals as well but be ultra responsive and be under $600.
a cast and billet 78/75 turbo started to see 100kpa at 3k and full boost by 4500k which was 13psi. I ran a 76/65 cast .84ar for a hot sec but no info as it was short and jumped around trying ti figure out boost issues. I just pulled my billet 10 blade 78/75 for the new Next Gen billet 70/70 from VS racing. He told me it would be done around 800hp but I should
see 500rpm sooner spool on my combo. I’m hoping it works out great for me as I’m only street and getting into boost sooner would be a lot more fun and I don’t need more than 700hp or spin higher than 6500. On the 6.0 the exhaust side is a bit small but I could see u still spinning to 6000 maybe and would be even more responsive. I think a billet 69/73 borg copy from VS in thr .9ar would be a nice fit and offer a bit more flow but still spool really fast on a 6.0. That turbo should meet your power goals as well but be ultra responsive and be under $600.
5.3 sloppy stage 2 cam vsracing billet 78/75 gen2 .96ar. Hit hard and quick. On transbrake 0 to 12 psi in less than a second. I never had to bump in. When both car where staged, I would floor it and always be on the chip by last yellow bulb. On the street it hit violent like nitrous.
Does anyone have any experience with using a smaller turbo for maximum spool time , street car.
just put in a th400 , 4200lb car.
going on a 6litre , l76 , 862 heads
im thinking a small cam with very little overlap will be needed with the higher backpressures of the smaller turbine.
thinking something along the lines of 10psi hopefully getting close to 700flywheel hp
s475 with a 0.9 a/r turbine
or a s300 s369 0.9ar turbine ?
maybe a btr stage 1 turbo cam , or even a cam motion reverse split ?
going with a 3.23 rear gear
just put in a th400 , 4200lb car.
going on a 6litre , l76 , 862 heads
im thinking a small cam with very little overlap will be needed with the higher backpressures of the smaller turbine.
thinking something along the lines of 10psi hopefully getting close to 700flywheel hp
s475 with a 0.9 a/r turbine
or a s300 s369 0.9ar turbine ?
maybe a btr stage 1 turbo cam , or even a cam motion reverse split ?
going with a 3.23 rear gear
Andrew
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FWIW I have a very similar set up . I'm at 4500 lbs street driving , 3.73s and 30" tires ( could be close to your 3.23s if your tires are 26 -27 ") am using 4l80e but 1st 3 gears are the same . Cam & springs only in lq4 ( cathedral vs your rec heads ) cam is single pattern cam motion 214/214 113+3 (I like small cams ) Cast vs 7875 . I figured the cam and turbo would both run out of Breath around 6000 rpm , I've since been proven wrong by rel3rd - on the turbo at least. Never dyno'd but wallace calculator says it's a bit over 600whp, pump gas 10g/hr WM. Spool is definitely not a problem, traction is ! Probably not the most efficient set up but it meets the goals , is cheap and is a compact and lightweight turbo . Cam idles @ 16-17 " vacuum @700 rpm in gear and can pull up a hill at 1500 locked up in OD with a bit of weight in it. I'm sure this could be done with a bigger cam but I didn't trust my tuning abilities LOL hope this helps
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With an lq9 and a '02+ls6 cam, my neighbor's Escalade could brake boost over 5#s with a Garrett that everybody calls a gt67 with no line lock or transbrake. We never upgraded his fuel pump, so I don't know at what rpm it would choke out. We just set his transmission to shift right before it ran out of fuel. Still got mid 12 second 1/4 times out of a full weight Escalade. I imagine in a car that weighs less than a battle tank that would be fun on the street.
I have been looking into diff turbos for a new project, have used a few diff ones, but found this
vid from Richard Holdener, pretty interesting.
RESISTANCE IS FUTILE-BATTLING BORGS - YouTube
vid from Richard Holdener, pretty interesting.
RESISTANCE IS FUTILE-BATTLING BORGS - YouTube
Andrew
I was surprised the larger S475 spooled that much quicker than the 78/75, even with the diff. in the A/R's. I had a Borg with the 1.25 A/R, I switched the housing to a 1.0, picked up the spool a little. I just figured the larger turbine would be a little lazier.
Need more info from OP before suggesting anything. What is the vehicle used for? Tire size? ET goals?
The motor only makes 355 crank as is. They dyno like 315/320whp. You can't put the worlds smallest cam and a baby turbo on it with insanely tall gears an expect 1000whp combo that runs well. That’s now how it works. Simple math... takes 1 bar (15lbs) to double na HP at crank. So around 700 at 15lbs on an efficient setup. Put a 3.20 gear on it and its going to hang at peak torque, accelerate poorly, and munch the engine.
Look at the video where Matt Happel goes from an 78/75 to a t6 S480 and picks up 100+hp at the same boost and spools MUCH quicker. T4's don't belong on 1000whp 6.0's as a single... ever. Not saying it can't be done... but if you aren't class racing its like tying 1 arm behind your back for no reason. A competitive 76mm class t4 turbo will cost you 3x what a basic T6 or other large frame turbo would. You don't see any T4 class guys with a box stock 78/75 from vs racing.
If you just want a fast street car to play in 1000whp is excessive and not needed.
The motor only makes 355 crank as is. They dyno like 315/320whp. You can't put the worlds smallest cam and a baby turbo on it with insanely tall gears an expect 1000whp combo that runs well. That’s now how it works. Simple math... takes 1 bar (15lbs) to double na HP at crank. So around 700 at 15lbs on an efficient setup. Put a 3.20 gear on it and its going to hang at peak torque, accelerate poorly, and munch the engine.
Look at the video where Matt Happel goes from an 78/75 to a t6 S480 and picks up 100+hp at the same boost and spools MUCH quicker. T4's don't belong on 1000whp 6.0's as a single... ever. Not saying it can't be done... but if you aren't class racing its like tying 1 arm behind your back for no reason. A competitive 76mm class t4 turbo will cost you 3x what a basic T6 or other large frame turbo would. You don't see any T4 class guys with a box stock 78/75 from vs racing.
If you just want a fast street car to play in 1000whp is excessive and not needed.