HELP! Stock boost valve boosting too low?

[Jpowys]

Hi Guys,

I'm worried my stock boost valve is boosting too low on my 33. It is completely stock besides 3 inch cat back and a pod filter. Watching the stock boost gauge, it only seems to boost to the middle +ve mark (i would assume 3.5 psi) up to 4500 revs and then to about half way up towards the 7 on the gauge (5.5psi perhaps?). This is probably a bit unclear and difficult to explain, but it looks like it is only boosting to 5.5 psi max. Do you guys think this is a fault in the gauge, or the stock boost valve? Or is this normal?

Any help would be extremely appreciated, i don't know whether to be worried or not...

Thanks in advance

[paulr33]

its normal operation. see below if you want to change it. stock boost on the r33 is 5psi until 4500rpm then its 7psi

http://www.skylinesaustralia.com/forums/sh...ead.php?t=42895

[johnbgoh]

Hi Jeremy,

I can think of three things

1. Yes your boost gauge could be faulty

2. The wastegate spring tension could be worn hence unable to get to the max 7 psi.

3. The turbo could be worn. Maybe the impellars/blades are worn.

My 2c worth

[rs73]

If you're talking about halfway between 0 and +7 on the stock boost gauge, then it is perfectly normal. The scale on stock boost gauge is NOT in psi but in x100mm Hg (mercury)

(1 Bar = 750 mm Hg)

Therefore +7 (maximum value) = 7x100 = 700mm Hg = +/-0.9 Bar = +/- 14 psi.

Stock R33 should boost to a little below the middle mark between 0 & +7 (around 5 psi) up to 4500rpm then around the middle mark (7psi) above that - as said by paulr33.

[The Mafia]

I was just about to say that

all the way to +7 = 14psi

halfway = 7psi

But that guage is shit, get an aftermarket one

[Jpowys]

Thanks Guys,

I appreciate it heaps! I won't worry any more then. And Yep, i'll be doing that mod to make it boost to 7-8 all the time rather than just 4500revs plus.

Jeremy

[paulr33]

enjoy