Help please!! Only 208bhp on dyno :-( what could be wrong?

[ryry92]

The turbo boosts, and at about 3000rpm reaches a healthy level.
Nissan decided that to be 10psi.
Many SXOC people have decided it should be more than that

Higher than 3000rpm, the turbo would simply run away if it is not controlled, so we have boost controller devices.
The boost level should be pretty constant from 3000 up to the redline.



This does suggest a sticky wastegate, rather than a boost leak.
(Some time ago) my own car decided to have little boost (on a trackday= annoying) until above 5000rpm. A whack with a hammer fixed it for a few hours, but it did need a replacement turbo for a permanent fix.
The spot weld in question was too far gone in my case.

I think I misunderstood what you said.. I'd need to video my boost gauge and speedo simultaneously. . But I know my tubby kicks in on boost at 3-3.5k .. what I meant was the gauge hits around 11/12 psi at 6-6.5k revs. . My boost doesn't hit 11 psi at 3k and stay there all the way to 6k


I hope I'm not confusing lol

Ry

[Jon]

My boost doesn't hit 11 psi at 3k and stay there all the way to 6k

Not confusing at all but ^^^ that is essentially what it should be doing

EDIT: for clarity, all these numbers only relate to full welly acceleration.
If cruising along you can be doing 4500rpm and still be at zero boost.

[s15 andy]

Yea I think I understand :-/ lol cheers for the pointers much appreciated

[Jon]

Yea I think I understand :-/ lol cheers for the pointers much appreciated

Sorry, your thread did get a bit ambushed.

S14 and S15 mechanicals are almost identical though, so same ideas apply.
If your boost peaks at much more than 3000rpm, then you could have a boost leak or some other issue.

The sticky wastegate arm I believe is an S14 thing only, though S15 turbos were a mixed bag (ball bearinged or not T28s) and I've never been sure which model or year had which one.