Stock Rb20 Boost

[mark32gts-t]

I've just installed a boost gauge on my car with intentions of boosting it slightly in future. Everythings stock except for 3" full exhuast but still with stock cat.

From what I've read the stock boost on a R32 is meant to be 10psi, whilst taking it for a drive WOT in 3rd its hitting 12psi but holds there. so not spiking. Any thoughts on why its running 12psi? considering everything is stock...

[paulr33]

as per the nissan service manual - and i quote;

Swing valve controller inspection

- Use the air gun to blow compressed air approx 0.8 ~ 0.9 kgcm2 into the hose and make sure the swing valve controller rod operates. Stop blowing air as soon as the rod operates.

So an average of 0.85kgcm2 is 12.08984 psi - so 12psi is stock actuator

RB26 is the same but 0.7 to 0.8kgmc2

R33 manual is 385mmhg which is 7.4446 psi

R33 auto is 270mmhg which is 5.220 psi

[rad100]

12psi hmmm i always thought 10psi was stock interesting

[sonoramicommando]

it should be less than 12psi at the plenum due to pressure drop across I/C & pipings.

[JAS-25T]

varies by the time it gets to the motor - so dependant on where you are measuring it could vary somewhat.

[mark32gts-t]

the line is being tapped from the inlet manifold. so this 12psi is after I/C and piping

[sonoramicommando]

Paulr33 is right in that it's about 12psi when WG actuator starts opening up.

I tested my r32 actuator yesterday and it does open up at 12psi, R34 one opens up at 6.5psi.

with r32 actuator, i get about 11psi peak and drops down and stabilise at 10psi.

your actuator might open at 0.9kg/cm2 and if you take the pressure loss thru I/C into account 12psi doesn't sound too unreasonable.

im going to put a spare boost gauge T'd up off turbo compressor housing nipple just to make sure what boost the turbo s making.

cheers,

sam

[R33Matt]

Stock boost for the R32 RB20 turbo is 10psi. On the R33 RB25 turbo the boost is 5psi until 5000revs and then it becomes 7psi. The reason you would be getting 12psi is become you have the aftermarket exhaust system. The 3inch dump pipe would allow more air flow from the turbo which gives you some more boost.

[sonoramicommando]

Stock boost for the R32 RB20 turbo is 10psi. On the R33 RB25 turbo the boost is 5psi until 5000revs and then it becomes 7psi. The reason you would be getting 12psi is become you have the aftermarket exhaust system. The 3inch dump pipe would allow more air flow from the turbo which gives you some more boost.

but wastegate actuator still opens up at the same boost level (12psi @ turbo compressor nipple), doesn't it? does that mean wastegate has not enough flow capacity?

i would have thought you would get higher boost at the plenum if your I/C & pipings are less restrictive than stock setup given the same wastegate & actuator.

cheers,

sam

Edited August 22, 2008 by sonoramicommando