What Causes Low/Restricted Boost ~4psi ?

sil SE · 08-21-2009, 08:56 AM

I've had my v2 installed since April, but never really got around to figuring this out.
3.125" pulley
Standard pancake air filter
Cartech FMU
255lph Walbro Fuel Pump
Budget Y-pipe
Warpspeed hi-flow cat (2.5")
2.5" catback piping (from my former megan exhaust)
3" Apexi WS2 muffler

I would've loved to have 3" piping all the way, but could the fact that it's 2.5" until the muffler have anything to do with restricting boost? (do SC respond to opening exhaust like turbo system?)

Belts are tight, and I've only been making this much according to my electronic boost gauge from the time it was installed by a quality/reputable tuner in my area.

thanks for looking.

*The Wizard* · 08-21-2009, 11:34 AM

Quote:

Originally Posted by sil SE

I would've loved to have 3" piping all the way, but could the fact that it's 2.5" until the muffler have anything to do with restricting boost? (do SC respond to opening exhaust like turbo system?)

It's definitely not that.

Does it feel like only 4psi??

Maybe your gauge is bad/installed wrong? What exact gauge do you have? Some Autometer gauges are a bit tricky to install correctly; they require the power wire to be hooked up to source that only gets power after the ignition is on....which re-calibrates the gauge every time you start the car.

Pull off your pancake filter as a test and go for a spin. See what you hit then.

Auto or 5spd?

dfownz · 08-21-2009, 11:41 AM

Is your belt tight?

*The Wizard* · 08-21-2009, 11:43 AM

Quote:

Originally Posted by dfownz

Is your belt tight?

He says so. Second to the last sentence.

sil SE · 08-21-2009, 12:31 PM

hi guys, thanks for the input.
the belt seems to be properly tense, and deflection seems about normal last time i looked and poked at it.

it's a 5 speed. i'm going to pull the filter like you suggested, wizard, yet when i first got the car back from the shop in april, the filter was loose all the time and fell off much of the time so i was running with an open turbine.

they are Prosport gauges, which isnt quite an autometer or defi (though many are partial to autometers), but ive used them before on my Evolution and found them to be pretty solid. boost gauge in particular.

as for the feel, hey, the way it is now, ill take it. it pulls real hard and all, its just frustrating to see the psi not climb as high as id expect on the gauge.

had a TRD supercharger (roots style) on my v6 camry previously, and it would only make about 3.5-4psi too and supposed to be a 6psi pulley. so this stuff frustrates me.

but ill try your suggestion about the air filter pull. too bad its like 93 degrees here right now in NJ. man..

**Nealoc187** · 08-21-2009, 02:27 PM

boost leak is what i'd check for

sil SE · 08-21-2009, 02:44 PM

i ran her down the highway real quick withOUT air filter. 4psi to close to redline in 3rd.

on a SC setup, where would i check for boostleaks Nealoc? everywhere from the outlet of the blower through piping to the TB?
i would imagine so since thats the whole system, unlike a turbocharged motor.
am i wrong?
everything seems to be hooked up tightly. hmm

*The Wizard* · 08-21-2009, 11:22 PM

Next culprit would be the BOV IMO. Could be leaking under boost.

sil SE · 08-22-2009, 07:34 AM

very true!
its a blitz bov and i threw it on "as-is" from the previous owner of this kit.
i feel its probably dialed in right but ill find out how to adjust it.
i do hear it moving air on idle, which i believe is correct?

should i try to tighten it little by little so it still vents at idle, and see if i theres any increase in boost?

i recall doing boost leak tests on turbo cars with a spray bottle/mist to see if there were any problem areas, but would this apply here at all?

agh im definitely a step behind you guys but i do appreciate the input VERY much.