IHI RHB5 turbo on d15b7, automatic transmission @ 7-8 psi.

here's the rundown in terms of RPM's:

1000-2000rpm:O vacuum, 0 boost.
2000-3500rpm:jumps from 0 psi to 7 psi
3500-5000(ish):full boost
5000-7000rpm: boost cuts from 7psi to 0psi, then stays like that until the car shifts, causing a drop in acceleration

*SHIFT
3500rpm: full boost*
last three steps, repeat themselves over

I DON'T KNOW WHY THIS HAPPENS? should i bleed the boost to lower the max psi. or is this the downfall to having a turbo that spins up too fast?

 

well , to be honest, I have no idea what to think...i know that the boost is supposed to remain at full boost until the car shifts, but it's just not happening.

 

my boost gauge is good...the rpm's increase much slower after 5k. there are no leaks cause I have spent many days of testing to ensure that there are no leaks...and there is no way a small leak can allow for full boost then drop to zero.

anyone else had this experience?

 

sounds to me like your blow off valve is opening too early or your wate gate is opening

 

__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote

 

how big is your turbo? it sounds like you make be having both a problem with your wastegate and your turbo running out of breath. like the think reaches peak boost and then the blow off dumps the rest out, then it need to spool up again. thats my guess.

nigel

 

nigel , that's exactly how it feels like when i drive the damn thing...i lowered the boost and i'll have to test it later tonight.

 

what sort of BOV are you using?