serious lack in HP please help

[TSiBill]

perviously i had a 50 trim turbo with 625 injectors, 255 fuel pump, fuel regulator, fuel rail, fuel lines,S-afc2, hahn front mount, tubular manifold, Forced performance stage 2 cams, and some other misc. mods. When it was tuned on a dynojet dyno it only put down 304HP and 289FT-LB at 19psi with a very late spool. I was told that the results were so low because the turbo was a hybrid so the comprosser housing was mitsu style and it was just a poorly built turbo. also they said that the injectors could not handle more.

I now just switched over to a PTE gt3076r and replaced the injectors with 880cc and after the tune it it put down 324hp and 299FT-LB at 22psi and still with a late spool. The shop told me that that is about 50hp under what was to be expected. also there are no boost leaks, and both a compression and leakdown test showed the engine to be in fine shape. The shop now says the low results could be caused by the injectors being too large, the afc not being able to set enough correction on them, or the cams having to much lift and duration for the turbo.

I am hesitent in deciding what to do next because last time the shop blamed the low results on the turbo and now it is still about 50HP under expected. So please any advise would be greatly appriciated

 

[flyinghighlm]

So you are using a SAFC to tune 880's? If that is the case then that could vary easily cause your problem. Those 625's were almost at the peak of what AFC's can handle and that is 650's. Mroe than likely you need to look into dsmlink now with all you mods and you should see way more power

 

[absolute_DSM]

What RPM are you considering a "late spool"?

And yes you would be better off using DSMlink or something along those lines for that sized injectors.

 

[kenamond]

As I understand it, when you're using SAFC, you deceive the ECU about airflow (tell it you have less than you actually have). This airflow is also used for your timing. It may be advancing timing too much, because the ECU thinks you're at a different airflow. This may lead to knock issues that screw up your timing. DSMlink or similar let you "do it right" instead of lying to your ECU. That's why folks don't push SAFC past 650s. Now this is all based on my reading WAY TOO MANY THREADS so you might want to get confirmation from folks with real experience.

 

[MrBoxx]

With 880cc injectors, you NEED DSMLink. I highly recommend you get it as soon as possible and without making any other changes to your setup, re-dyno and re-tune using Link and see how much your results change. I don't think you'll be disappointed.

 

[TSiBill]

The original 50 trim did not hit full boost (19psi) untill about 5200 rpm and the GT3076R hits full boost (22psi) at about 4500rpm. The shop told me that it would see full boost at 3800rpm.

 

[olmytsi]

4500 sounds about right. The 5200 however was not right.

Two things you are doing wrong:

1- afc with big injectors/lack of tunability/monitoring of vital elements such as knock.

2- running low boost and expecting big numbers out of a big (relatively) turbo.