low HP/TQ on STS LS2 GTO?
low HP/TQ on STS LS2 GTO? I had to replace my stock shortblock in my 06 LS2 GTO due to #7 ring failure. I went forged with dished pistons. While I was rebuilding it I replaced the LS2 cam with an LS9 cam and LS7 lifters. The motor is a low compression build because I want to run 14-16PSI boost.
I got it tuned but it seems really low. 380RWHP/400TQ @5PSI with a tc76 turbo. I was expecting almost 100rwhp more closer to 460-480rwhpwith this setup on 50/50 Meth. Am I wrong?
I got it tuned but it seems really low. 380RWHP/400TQ @5PSI with a tc76 turbo. I was expecting almost 100rwhp more closer to 460-480rwhpwith this setup on 50/50 Meth. Am I wrong?
Your mixing some different numbers together that don't always have direct relationships.
Your PSI numbers are coming from a compression test. Compression test results are influenced by compression ratio, but the camshaft profile also has a large impact.
Your ratio numbers are static compression ratio, they do not take into account the amount of stroke that the intake valve is open. A better way method of comparison is dynamic compression ratio, in your case the dish pistons plus a different cam reduced the dynamic compression ratio significantly.
Low compression + big cam = low compression test results.
Good side: If you are ever in a pinch, you can turn down the boost (or just stay off the throttle) and get away with running 87 octane.
Bad side: The car will probably be lazy out of boost, and fuel milage will probably not be as good as before.
As others have stated, the max power number should improve quickly as boost is increased.
The LS9 cam may not be the best option for a turbo, as it was designed for use with a pd supercharger.
Your PSI numbers are coming from a compression test. Compression test results are influenced by compression ratio, but the camshaft profile also has a large impact.
Your ratio numbers are static compression ratio, they do not take into account the amount of stroke that the intake valve is open. A better way method of comparison is dynamic compression ratio, in your case the dish pistons plus a different cam reduced the dynamic compression ratio significantly.
Low compression + big cam = low compression test results.
Good side: If you are ever in a pinch, you can turn down the boost (or just stay off the throttle) and get away with running 87 octane.
Bad side: The car will probably be lazy out of boost, and fuel milage will probably not be as good as before.
As others have stated, the max power number should improve quickly as boost is increased.
The LS9 cam may not be the best option for a turbo, as it was designed for use with a pd supercharger.
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It could be the combo, cam could be off a touch, could be a lot of things. What's the trans in it? Stalled? What did the dyno look like? What was the AFR? What intercooler? What turbine housing on the TC? Fill in the details and we'll try to help ya out.
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Its a MT factory T-56. Its the stock STS intercooler. I' also running 50/50 meth injection. The turbo is a P trim with the .81 AR housing. It was speced for a rea-mount setup. I attache dthe dyno chart.
If your still running a maf first thing I would do is clean it with some maf cleaner, there's a thread by schalling and a dirty maf will cost you alot of power. I would turn the boost up to 8-9lb's and see what numbers you get. Make sure your injectors and fuel system can handle the extra boost.
I am running the 38mm tial that came with the STS kit. I guess it will be tested during the leak test as well. I guess I should take the air folder off and connect the leak tester to the inlet on the turbo and see if I can get it to hold 5psi.
