ive got an idea to check and see if the exhaust backpressure is the true culprit to the boost drop. ive got an extra turbo downpipe for the aps kit, what i plan to do is have a 2.5" electronic cutout installed right at the turbo. the downpipe kinda curves in front of the turbine so im gonna try to get it welded up straight in the line of the exhaust gases so they shoot right out.

its gonna be before the 02 sensors and my WB, will this cause me problems with the AFR and my 02 sensors?

 

Tig,

Sorry I am missing something. What is different than just dropping the exhaust after the down pipe? Which we both did (I think) and little improvement.

 

Would be far easier to just measure the ex back pressure imo.

 

boost pressure is dropping on a 2.5" downpipe on a small gt28? doubt it. id look at a better boost controller..

also what u plan do to will expose the cutout to temps way beyonds its recommended range IMO. Also u are cutting out ur wideband/o2 sensor so u will cause a few cels to be throw and possibly put off ur partial throttle tune cause the ecu will be confused.

 

beastie, i think that the part causing all the problems is the pipe bolted directly to the tubro which has the 02 sensors in it. i can drop that pipe. i dropped the curved pipe.

weqster, 2.5" dp? gt28? ive got the single kit not the twins.

 

don't put the cutout before the o2 sensors.

 

therein lies the problem i was afraid of.

 

Downpipe is 3.5 is it not tig? And its a gt35 not a 28. Run open exhaust on the dyno and you will see a difference at least i did. Should have bought my exhaust....

 

dave, when can you ship those other parts to me, i think im gonna need them pretty soon. just say when and ill send the money.

 

my bad, didnt know it wa sa single

 

so i took my car to get the exhaust backpressure tested today, and exactly as i susptected, i had almost NO backpressure, at 2500rpms the needle barely moved off zero, i revved it to 6500, and got 0.5 lbs, so i guess my exhaust is free flowing. on to other possible causes.

 

You won't see the real back prerssure figures unless you're under full engine load.

 

how the hell can you measure that, on a dyno? thats gotta be a PITA to check it like that on a dyno.

im glad i wasted that GD $35!