Changed turbos and slow my car down any ideas?

[southern boost]

I changed turbos from a pt 61 to a pt 67 the best i went with the 61 was 11.27 at 119.74 and now with the 67 i can"t get pass 11.57 at 115.78 ,so what would anyone think both turbos where at 25 psi . They both had good hard launchs ,but the smaller had a better 60ft . The o2s drop every pass good with the bigger turbo,but it just won't et with the smaller set up that i had on the car.


the only change was turbos .
does anyone think a chip change would help?

any suggestions would be helpful.



thanxs randy

 

[kidrick]

I would look at bigger injectors, reprogammed chip for the turbo and maybe a higher stall(3,500).

 

[GN SBS]

You might look up some of Carl Ijams posts on the 67 and see what he thinks. As I recall, he switched from a smaller turbo to the 67, didn't see gains and concluded that the swap tested the limits of the factory unported heads.

I couldn't see how the injectors would fix anything unless you see something related to fueling, which doesn't sound like it is the case.

Scott

 

[wiked87gn]

50's are ok, running lean on top end is expected with bigger turbo, give it more fuel by incresing fuel pressure, to get better 60's you will have to get higher stall if you dont have anything above 3,200 stall then that is where ur 60's are hurting higher stall launch harder and ur there, porting heads and intake also helps a bunch, that alone if you have not done it will bring you at least an extra 80hp to play with, once again if you are going to be running low 11's to high 10's i would start looking at reinforcing the bottom end it never stops man. good luck.

 

[KillrV6]

more timing, more stall

 

[ijames]

Yeah, what Scott said . Didn't see any gain but didn't slow down either, going from PTE54 to GT67, ran 110 mph either way on 93 octane and about 24 psi boost. If I ever get good heads installed I should see a big gain if that's what's holding me back. You say you see the O2s dropping - any chance you are really flowing more air and are going lean now? My stall is about 3200 advertised, about 2900 rpm at zero psi boost, and it spools real quick if I footbrake up to 4-5 psi. Actually, the 67 spools as fast as the 54 did.