Low rwhp on twin turbo setup
09-07-2010, 09:24 AM
#61
Does anyone know what the normal boost drop is for a rear mount setup? Mine is 20 at the turbo and 10 at the manifold, that sounds way too high. Thanks!
09-07-2010, 12:30 PM
#65
I've only really been into turbo cars for the last 5 years, but this thing I know: Leaks are a killer. Make sure there are no leaks on either exhaust or boost side before thinking anything is wrong. Your boost drop is way too big. It should be no more than a psi or two from the turbo to the intake manifold unless there is a leak, some restriction or an inefficient intercooler.
Oh yeah and turn the boost down before testing it after fixing stuff so you don't end up putting 20psi to the motor...
Oh yeah and turn the boost down before testing it after fixing stuff so you don't end up putting 20psi to the motor...
09-07-2010, 12:42 PM
#66
I've only really been into turbo cars for the last 5 years, but this thing I know: Leaks are a killer. Make sure there are no leaks on either exhaust or boost side before thinking anything is wrong. Your boost drop is way too big. It should be no more than a psi or two from the turbo to the intake manifold unless there is a leak, some restriction or an inefficient intercooler.
Oh yeah and turn the boost down before testing it after fixing stuff so you don't end up putting 20psi to the motor...
Oh yeah and turn the boost down before testing it after fixing stuff so you don't end up putting 20psi to the motor...
09-07-2010, 07:51 PM
#67
Well, i'm narrowing it down.... i have the same boost at the front of the throttle body as my turbo's at any given boost level.... once i checked it at the first vac port after the throttle body, it started to have a big boost drop. So obviously the intake or something on the intake is leaking big time.... I thing i noticed when i had the vacuum gauge on the first vac port after the throttle body is the vacuum was a couple pounds higher than when it is mounted at the rear of the intake.... so the leak is prob somewhere near the rear of the intake. I ran out of daylight so i will check it tomorrow. Thanks!
09-07-2010, 08:15 PM
#69
it is a large port but i just installed a new 3 bar map yesterday with no change in the boost leak..... I double checked all of the o-rings in the manifold (they were new with the new engine) but i must admit i wasn't looking for an intake leak yesterday so i didn't remove it completely. I guess the best way to test it is to pull the covers and loosen the valves.... oh well, at least i'm close..... 
p.s.... are the ls6 manifolds known for cracking? Thanks!
p.s.... are the ls6 manifolds known for cracking? Thanks! Last edited by TracyRR; 09-07-2010 at 08:25 PM. Reason: fixed
09-07-2010, 09:23 PM
#70
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I'm confused because if your loosing boost at the intake you should have a huge vaccum leak, I would try spraying carb cleaner around the intake and seeing if it causes a idle change.
09-07-2010, 10:28 PM
#71
hey mike, your right... I was working on it tonight and noticed the aeromotive fuel rails were putting the injectors at a funky angle so i clearenced them a bit and they straightened out. After it was running, i did notice a hissing sound that i couldn't put my finger on.... I'm sure it was there the whole time but obviously i didn't pay close enough attention..... if i would have had carb cleaner, i would have used it but no luck tonight. I will get some tomorrow though. Thanks!
09-07-2010, 10:38 PM
#72
FormerVendor
I assume you verified that the throttle body is opening 100%?
09-07-2010, 10:56 PM
#74
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even with tuning he could only get it to 97% but it still made a huge difference
09-07-2010, 11:30 PM
#75
im curious if more power will be made with the fixes.
on the intake side, even with the fixed leaks, the engine will still be seeing the same pressure.
on the exhaust side, with a wastegate limited 10psi, the turbo sees the exhaust or it goes out the wastegate.
I get that the turbo is working harder creating more heat. is there anything else that would cause the engine to make substantially more power at the same boost level?
on the intake side, even with the fixed leaks, the engine will still be seeing the same pressure.
on the exhaust side, with a wastegate limited 10psi, the turbo sees the exhaust or it goes out the wastegate.
I get that the turbo is working harder creating more heat. is there anything else that would cause the engine to make substantially more power at the same boost level?
09-07-2010, 11:50 PM
#76
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im curious if more power will be made with the fixes.
on the intake side, even with the fixed leaks, the engine will still be seeing the same pressure.
on the exhaust side, with a wastegate limited 10psi, the turbo sees the exhaust or it goes out the wastegate.
I get that the turbo is working harder creating more heat. is there anything else that would cause the engine to make substantially more power at the same boost level?
on the intake side, even with the fixed leaks, the engine will still be seeing the same pressure.
on the exhaust side, with a wastegate limited 10psi, the turbo sees the exhaust or it goes out the wastegate.
I get that the turbo is working harder creating more heat. is there anything else that would cause the engine to make substantially more power at the same boost level?
09-08-2010, 09:11 AM
#77
im curious if more power will be made with the fixes.
on the intake side, even with the fixed leaks, the engine will still be seeing the same pressure.
on the exhaust side, with a wastegate limited 10psi, the turbo sees the exhaust or it goes out the wastegate.
I get that the turbo is working harder creating more heat. is there anything else that would cause the engine to make substantially more power at the same boost level?
on the intake side, even with the fixed leaks, the engine will still be seeing the same pressure.
on the exhaust side, with a wastegate limited 10psi, the turbo sees the exhaust or it goes out the wastegate.
I get that the turbo is working harder creating more heat. is there anything else that would cause the engine to make substantially more power at the same boost level?
09-08-2010, 10:54 AM
#78
FormerVendor
A turbo producing 20psi so the engine can see 10 requires more power to drive than a turbo producing 10psi and the engine seeing the same.