Help with Boost/Tuning please!

[mccurdy]

I just swapped a 3'' downpipe onto my 97 GST. Im running a Junior frank 19C ported/clipped. I had stock dp on b4 and the car actually was FASTER b4 the new DP! why could this be?

Extreme said maybe a MASSIVE boost leak, but ican reach 20psi on my profec-b. I dont get full boost till around 4,700rpm's though! I noticed it goes from 8-20 psi a LOT faster than it going from 0 to 7psi. Could this be a leak somewhere or turbo just gaining momentum?

thanks guys

 

[1fast97gsx]

do a boost leak test ... that downpipe should help performance not hurt it. You've gotta be leaking somewhere. Does it spool faster or slower now? Max boost at the same rpm?

 

[NOSNUSE]

It might just be the fact that the larger pipe hurt your low end power because at low rpm you don't need a huge pipe, but once the turbo has spooled and you start pushing more air through the motor you need the larger pipe to make high end power.

 

[mccurdy]

I did a leak test awhile ago and didnt find anything. I dont have one now so i gotta build a tester, but the 19C turbo is 2 1/4 inlet housing, and no place sells 2 1/2 sized rubber tubings. OSH dont have anything...might home depot? What should i use to push the air in also? people say bike pump nozzles, what should i use? My friends got a compressor so.....

But ya i just bogg and build boost really slowly until like 3,500 rpm. I reach full boost by usually 4,500 rpm in 3rd gear, a little later for lower gears. Someone please help. What could cause this?!?! the downpipes actually hurting performance. i spooled faster without the downpipe, i should spool faster! WTF

Thanks guys.