Has anyone actually run a comp turbo on an lsx?
#24
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For comparison, here are 2 dyno sheets from 346ci 6-speed cars.
ITS 76mm R-Trim, 17psi-
![](http://www.ls1speed.com/artwork/elim/ownz.jpg)
Precision 76GTS 18psi-
![](http://www.ls1speed.com/pictures/turbo12_12.jpg)
Both turbos were tapped out as far as power/boost if I remember correctly. You can see that even on 346ci they are done by 6k rpm.
ITS 76mm R-Trim, 17psi-
![](http://www.ls1speed.com/artwork/elim/ownz.jpg)
Precision 76GTS 18psi-
![](http://www.ls1speed.com/pictures/turbo12_12.jpg)
Both turbos were tapped out as far as power/boost if I remember correctly. You can see that even on 346ci they are done by 6k rpm.
#25
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With my drivetrain that would probably be 800whp. Id be fine with that but if my back pressure is already really high I couldn't imagine 18psi. Jim, what turbo would you recommend given the space I have to work with?
#26
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You can see my dyno chart of a 7875 at the link below. Keep in mind this is through a 4L80e with an unlocked converter, 370ci. Doesn't seem to fall off as bad as the 346ci graphs above.
https://ls1tech.com/forums/forced-in...6rwhp-e85.html
https://ls1tech.com/forums/forced-in...6rwhp-e85.html
#27
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Lets start off with some tests and go from there. For example, if you have a lot of pressure drop across the cold side that will only further increase exhaust backpressure so changing just the turbo could only help to a degree.
Really I'm not a fan of running any single T4 turbo. It may make some good peak numbers if everything is is sorted out but you won't have a very high usable rpm range.
I prefer a set of small twins. Very fast response and a lot more usable rpm. Something like twin 35r's or 6262's can make 1000rwhp and be shifted at 7k+rpm. Twin 67's can do about 1200rwhp and barely taper off power wise up to nearly 8k rpm on a hyd roller.
Really I'm not a fan of running any single T4 turbo. It may make some good peak numbers if everything is is sorted out but you won't have a very high usable rpm range.
I prefer a set of small twins. Very fast response and a lot more usable rpm. Something like twin 35r's or 6262's can make 1000rwhp and be shifted at 7k+rpm. Twin 67's can do about 1200rwhp and barely taper off power wise up to nearly 8k rpm on a hyd roller.
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Id love to do twins but funds are not going to allow for that. My goal is to run 9s which I should be able to do with a good size and properly matched single. I guess ill just wait for the back pressure and pressure drop results and go from there. Thanks again Jim for getting into a customer built car. I tried my best to get it ready to dyno with no issues. A side from the turbo the rest of the kit has worked very well in the last 3 years.
#29
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Lets start off with some tests and go from there. For example, if you have a lot of pressure drop across the cold side that will only further increase exhaust backpressure so changing just the turbo could only help to a degree.
Really I'm not a fan of running any single T4 turbo. It may make some good peak numbers if everything is is sorted out but you won't have a very high usable rpm range.
I prefer a set of small twins. Very fast response and a lot more usable rpm. Something like twin 35r's or 6262's can make 1000rwhp and be shifted at 7k+rpm. Twin 67's can do about 1200rwhp and barely taper off power wise up to nearly 8k rpm on a hyd roller.
Really I'm not a fan of running any single T4 turbo. It may make some good peak numbers if everything is is sorted out but you won't have a very high usable rpm range.
I prefer a set of small twins. Very fast response and a lot more usable rpm. Something like twin 35r's or 6262's can make 1000rwhp and be shifted at 7k+rpm. Twin 67's can do about 1200rwhp and barely taper off power wise up to nearly 8k rpm on a hyd roller.
Last edited by beautie; 09-23-2011 at 05:32 PM.
#34
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#35
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Who likes data?
I just put this car on the dyno to test cold side pressure drop and exhaust backpressure.
Run was made with AEM boost controller at 90% duty cycle (max)
Manifold pressure- 11psi
Pre-intercooler cold side pressure- 15psi (could probably be corrected by having an intercooler with inlet/outlet inline with the core rather than forcing the air to make 90deg turns at the end tanks)
Exhaust backpressure- 45psi
I just put this car on the dyno to test cold side pressure drop and exhaust backpressure.
Run was made with AEM boost controller at 90% duty cycle (max)
Manifold pressure- 11psi
Pre-intercooler cold side pressure- 15psi (could probably be corrected by having an intercooler with inlet/outlet inline with the core rather than forcing the air to make 90deg turns at the end tanks)
Exhaust backpressure- 45psi
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#40
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Wow that is nuts!
Curious too about your exhaust
I know on my GTS with the full 3" exhaust and two mufflers in series it plateaus around 12psi
But when I open my cutout which is directly off the turbo the change is crazy, it picks up a butload of power and I can bring it up to 14psi very easy still gaining a bunch with each #
Curious too about your exhaust
I know on my GTS with the full 3" exhaust and two mufflers in series it plateaus around 12psi
But when I open my cutout which is directly off the turbo the change is crazy, it picks up a butload of power and I can bring it up to 14psi very easy still gaining a bunch with each #