Spool problems (GT67), need another turbo?

[Lunkan]

I was told that the GT67 with Q-trim would work good with my combo, but after 5 sec at 3200 it only produce 5PSI. What turbo would be a better choice for my combo?

- completely rebuilt and balanced 109 w/ JE .030 and girdle
- 212/212 hyd.roller
- 70mm Accufab TB, RJC powerplate, Precision plenum
- heads and lower intake are match ported
- stock heads smothed out w/ major bowl work, larger valves
- 3.5" LS1 maf and mafpipe w/ trans+
- stock IC w/ Duttweiler neck
- ATR 2.5" crossover
- ATR 3" DP and external WG
- 72lb injectors

I have no exhaust or vacuum leaks.

This is on t-brake, if trying to brake up the boost the tires only starts spinning and the boost comes at ~3500rpms.

Thanks in advance
/Andreas

 

[JaBoT]

What size converter are you running?
With a q trim I wouldn't go with less than 3800. I'm running a 3800 on a p trim and it spools just fine.

 

[Lunkan]

It´s a switch pitch TC that was listed as 4000+, but only stalls 3200.

Talked to a company here in Sweden that uses the same turbos, and they where surprised that I couldn´t spool it better.

 

[ijames]

Considering how quickly my P trim GT67 spools, and a friend's, both with 3000-3200 stall converters, I have to think you just need some fuel/timing tuning. From a dead idle we both get to 5 psi in less than 2 seconds just mashing the gas, with or without brakes. Try working with your fuel pressure to see what your setup likes. For now don't worry about the rest of the run, just get the spoolup where you want it. Then work with your chipmaker to put it all together.

 

[Lunkan]

At the moment I´m running an Extender Extreme chip. Under WOT in 3rd, the WB reads 11.9x.

I´m also trying to figure out whats wrong with my POSI, so it´ll take a while before I can start tune the car again s

 

[Taffy]

What is your timing and the AFR when you are on the converter/trans brake?

3200 is a little low for the GT67Q, but it still should be able to spool better than that on the brake. 3500 is a better bet. If you could stall it at the advertised 4K stall, you will spool that turbo like a mad man!