[bad94sup]

I've recently upgraded my turbo and injectors from a SP67 p trim .81 A/R and HKS 720s to a BL71GTQ and 880cc injectors, and the car is making less power at the same boost! I went from making 665whp unlocked with the 67 to 630whp with the 71 at the same boost level (31psi)! No knock on any runs...The car also consistenly made about 15whp on pump gas as well.

I've even tried running a bit more timing with the 71 with no success! (Running about 17deg peak torque and 19 to redline at 30-31psi) This was done on a dynojet (same dynojet for both) and about the same weather and altitude conditions. Fueling on both runs was low 11's A/F. Well I was thinking maybe the dyno wasn't telling all so I headed to the track and sure enough my trap speel fell from 139mph to 136! Talk about frustraction!!!...here is my exact setup maybe some of you guys can give suggestions to help me bring back my power

The only things I changed were the turbo and injectors....

SP turbo kit 71mm Q trim .81 A/R
3" Midpipe and downpipe (may be holding back a bit)
Apexi N1 cat back
Stock motor with exception of HKS 264 cams and crower springs/retainers
AEM EMS
Striaght c16 for fuel
Dual walbros/HKS rail
Dual -6an fuel feeds
Denso 880s
Stock cooling system
SP Gen II built trans with PI 4k converter
Dual B&M Tranny coolers 1 w/ fan
No nitrous YET :stickpoke
Denos IK24s at .028 (no misfire)
Think thats about it!!

Help me bring back the power!!

Thanks in advance...

-Andrew

 

[banton]

Could be other causes, but how is the condition/performance of your converter now vs. when you dyno'd the numbers with your 67mm set-up? Just a guess, but could your convertor be slipping more over time hence more driveline lose and lower hp numbers? :dunno:


Brad

 

[bad94sup]

Could be other causes, but how is the condition/performance of your converter now vs. when you dyno'd the numbers with your 67mm set-up? Just a guess, but could your convertor be slipping more over time hence more driveline lose and lower hp numbers? :dunno:


Brad

It seems to be peforming about the same...it still stalls to its point and hold solid power til redline???

-Andrew

 

[banton]

It seems to be peforming about the same...it still stalls to its point and hold solid power til redline???

-Andrew

Ok, like I said, just a guess. Other than stating the other typical responses like check compression/leakdown.....you might do a search on BLKMGK. I remember he was similarly surprised when he went from a similar set-up (T78 ) to a 71mm turbo, but I don't remember if he found a solution or not. Good luck.

Brad

 

[bad94sup]

Ok, like I said, just a guess. Other than stating the other typical responses like check compression/leakdown.....you might do a search on BLKMGK. I remember he was similarly surprised when he went from a similar set-up (T78 ) to a 71mm turbo, but I don't remember if he found a solution or not. Good luck.

Brad

Thanks for the help bud I've check the plugs quite frequently and they all looked perfect....guess ill do compression and leakdown next weekend Perhaps I'll go back to the 67P and maybe a bit of nitrous.....

 

[bad94sup]

Ok..its come to my attention I may have a boost leak...any other suggetsions or tips for testing for leaks??

 

[blkdawg]

Definitely do a boost leak test.
I just did mine and found 4 leaks! one was a major leak at the intercooler core and i still dynoed 600rwhp at 21psi.

john

 

[Viper TT]

Andrew,

Sorry to hear about your results. The only things come to mind have already been stated. Boost leak or motor issue.

Boost leaks can be tested in 1 of 2 ways. If you still have the protective cover that came on the turbo inlet, modify it to accept a port from your air compressor hose. Hose clamp the protective cover to the compressor housing and pressurize the intake system. You might have to bump the motor over until the intake valves are closed. Makes sure you are in a quiet environment and you will hear any obvious leaks. The other way I have used is somewhat rigged. Duct tape the compressor inlet closed and pressurize the intake system through the vacuum line attached to the compressor housing.

 

[bad94sup]

Andrew,

Sorry to hear about your results. The only things come to mind have already been stated. Boost leak or motor issue.

Boost leaks can be tested in 1 of 2 ways. If you still have the protective cover that came on the turbo inlet, modify it to accept a port from your air compressor hose. Hose clamp the protective cover to the compressor housing and pressurize the intake system. You might have to bump the motor over until the intake valves are closed. Makes sure you are in a quiet environment and you will hear any obvious leaks. The other way I have used is somewhat rigged. Duct tape the compressor inlet closed and pressurize the intake system through the vacuum line attached to the compressor housing.

Thanks Sal! Im going to do that this weekend....how do I know when all the intake valves are closed???