Car Is Boosting To 11psi (stock) No Bc

[3LGODZILA]

just installed a boost gauge (i Tee'd it into that line going from the back of the plenum to that little black box near the firewall) to my car as im waiting for my turbotech bc to come. on boost, on the stock gauge on the dash it reads about 1mm over the line inbetween 0 and +7, and on the boost gauge it reads 10psi when i kick the clutch a little it spikes up to 11psi, i havnt gotta boost controller installed and i only have minimal mods. i was planning to wind the boost up to 10-11psi (for the sake of the stock turbo) and get a catback exhaust soon, wont the catback bring the boost up very slightly aswell? reason im asking i read that a 33 with the usual mods (full zorst, some sorta intake ie pod of high flowing panel filter, FMIC) would be about 9-10psi without a boost controller and mines making more then that with less mods? or is this normal?

car is completely stock apart from the following:

3inch bellmouth dump/front pipe

gutted stock cat

earthed stock boost solenoid ground wire (the 1 that switches after 4500rpm)

k&n panel filter

r34 SMIC

blocked the hole off on the stock bov

[and3_3]

Freeing up the exhaust will mean it boosts quicker so you might have to adjust it slightly

[TaKz]

where did you get the boost gauge? is it name brand or ebay spec?

as some dodgy boost gauges may not give an accurate reading

[3LGODZILA]

its an autometer gauge, i think it says pro lite or something, i got it 2nd hand off a silviaWA member that claimed it was never used, it doesnt look like it was ever used either, mi factory dash gauge goes to full boost at like 2000rpm, this 1 shows full boost at like 2500rpm, and pretty much jumps to 10psi as the factory gauge gradually moves up

[lineskee 33]

sounds like your stock boost controller isnt connected or working at all. It sounds like the boost is being regulated by your wastegate spring which usually works up to around 11 - 13psi. Install a boost controller and you will proabably notice the issue fixed.

If you are worried about the guage, try borrowing another of someone else and see if it hits the same number when u hit full boost. I dont think there would be anything wrong with the guage.

[TaKz]

it's weird cause his stock gauge(which may not be accurate) is reading differently to his autometer gauge.

as 1mm above the half way point of 0 and +7 is approx 7psi

but i think i've read that aftermarket dump and front pipes increase the boost pressure as well so that could be the reason theres increase in boost where no boost controller has been installed.

[reNEGaDeR32]

Freeing up the exhaust will adjust the boost level. my R31 with a RB30ET should run 6psi. but since I put a 3" zorst on it ran ~10psi on my autoguage. My other mate ran no exhaust after he did his turbo conversion on his RB30 and his boost gauge also read ~10 psi.

[no_miss]

i have very similar mods and i was getting 8 and 10 psi before i grounded the standard boost solenoid last week (glad i did )

i had a look at my ecu and googled the code on it and the info i found said that it had a mines re-map before it was imported, so may pay to check that and see!?

not too sure exactly what else was changed with the re-map but boost was definitely one thing.

[3LGODZILA]

had a closer look at the gauges this morning (was pretty cold) it reads 11psi and 12 wen i kick the clutch a little, and on the stock gauge its definitely about 1mm over the mark in between half and +7 maybe even a little less. might have to try and borrow a gauge, btw is the ecu behind that cover near the passengers feet on the right?

[Jet 20]

is the standard guage measured in PSI or BAR??

[paulr33]

the standard guage is in mmhg

its not bar, its not psi, its not kgcm2, its not pascals

look up mmhg to work it out

half on the stock guage, ie between 0 and +7 is 3.5x100mmhg or 350mmhg

which is approx 6.7PSI

[no_miss]

Yup, the ecu is to the left of the passenger footwell, behind the kick panel.

not too sure how accurate the stock gauge is tho??

[paulr33]

stock guage is fine

[3LGODZILA]

so most probably my autometer gauge is out? on monday/tuesday ill try get my hands on anther one and see what happens

[paulr33]

well it depends

what are you using to increase boost over the stock level?

the stock gauge reads from the back of the plenum, so unless you change anything, its usually spot on

under full load the stock guage will read around 3/4 ish which is around 3.5ish around 7PSI ish

remebering that the R33 GTST has dual stage boost, so it should increase past 4500rpm to around 9PSI

if you have done the dual stage boost hack, it can run 9PSI all the time, even under 4500rpm

the only time two boost guages read differently are

1) user error - ie one is in KPA and one is in KGcm2 etc

2) they are reading from different locations

3) there is a vacuum leak somewhere - if so, it wouldnt make much boost, car would be sluggish

4) faulty gauge

[3LGODZILA]

ok guys i think i have a faulty gauge, i borrowed a mates from work and on the drive home compared them, i swapped them over about 3 times to make sure its accurate. my autometer gauge was reading 10psi and coz the needle would flick up so fast it wud go to 11psi then bak down to 10psi. when i used the VDO gauge it read 8psi and wen i was really booting it, it went slightly above 8psi not quite 9, and the stock gauge was reading a smidgen above the halfway mark between 0 and +7. (x100mm hg) So say its nearly 4 x100mmhg, thats nearly 8psi which is fairly accurate. now im happy ive still got another 4 psi to play with when i get my boost controller

EDIT: haha just gotta call from my mate like literally 1 min after i posted this, my turbotech manual boost controller just arrived, so im gonna play around with it now, talk about timing

Edited March 16, 2009 by xdef