I Think Im Overboosting

[Ruxis]

hey guys,

I have a really weird vacuum hose set-up for my boost.

I have a r34 gtt 2000 model, and i dont use a solenoid (bought the car like that), the turbo, actuator and BOV return vacuum lines are all T'd together and the stock solenoid is sitting there with nothing in it.

everything was alright however ive put a turbo back (split dump pipe) and pod filter on the car and it feels like its pulling way to hard. ive heard if you install a dump pipe your boost will rise but this feels like 12-14 psi also (i know its not accurate) my stock boost gauge goes up to +1 mmhg aka 14psi, id like it to sit on 10 psi all the time which i think would be possible without a controller if i could possibly set up my solenoid??

if those three hoses are T'd together would that mean the waste gate is permanently open??? because theres no control from a solenoid???

any help would be greatly appreciated

[zebra]

Do you have a pic of how its all setup?

[Ruxis]

do you one better, no way i would of fit it in a picture.

ive shown the piece and th vacant solenoid

[Moodles2]

+1 mmHg = 2.8psi (you probably mean +7 mmHg which is about 13.2psi)

1 bar = 14.5psi

[KiwiRS4T]

This is a good free way of increasing boost. Amount of boost is controlled by the restrictor in the bleed line that goes to the bov return. Personally if its going ok I would leave it alone but if you want to reduce boost you will have to reduce the size of the bleeder. Since you can't make the hole smaller you'll either have to put in a different restrictor with a smaller hole (say the end off a welding tip) or fill that part of the T with solder (or possibly bog) and drill it out again. What I have done in the past is put in a needle valve in that line to have adjustable boost!

[Ruxis]

Sorry it's +1 kg/cm2

Yeah fair enough. Do you know a cheap way to know what my boost is accurately??

I don't have a front mount so I'm Gunna have to do something.

Maybe I could a smaller size down t peice and clap my hoses down onto it. Think that'd be enough??

Can I set up the solenoid back to normal?? And will my boost sit on 10 cause of my other mods??

[GTSBoy]

Do you know a cheap way to know what my boost is accurately??

Go to friendly workshop, ask to hook their boost gauge up to your car, drive around block, win.

[Rolls]

Can I set up the solenoid back to normal?? And will my boost sit on 10 cause of my other mods??

If you aren't running a bleed valve you can't make your boost lower, you can only make it higher. You would need to change your wastegate actuator to run lower boost. Get a boost gauge on there, if it is only running 12psi then there is no issue, if it is spiking to 14 then dropping back to 12 it isn't that bad. If you are running 14 all the time then you should do something about it.

[Ruxis]

yeah thats a good idea.

hmm fair enough, how much would that cost???

im not running a front mount though and i dont really intend to, wouldnt that be bad?? if i wanted to do a track day id probly melt my turbo haha.

[Rolls]

yeah thats a good idea.

hmm fair enough, how much would that cost???

im not running a front mount though and i dont really intend to, wouldnt that be bad?? if i wanted to do a track day id probly melt my turbo haha.

If you aren't running a front mount then running 14psi is a waste of time, especially if you haven't had the car tuned. You will just be running very rich and retarded making barely any extra power and using a lot more fuel. With the stock tune the car is extremely safe due to how rich it runs (down to 10:1 and lower) it also runs absolutely bugger all timing so highly unlikely to break anything from the extra boost. The only thing that may break is the turbo due to the ceramic wheel, however you will only break it if you are holding 14psi close to redline and then holding it there for extended periods of time (high speed runs, track days etc).

I personally would get a FMIC, a tune and enjoy the extra torque that running ~12 psi gives you, I have a hard time believing tha tit is actually running 14psi with no bleed valve. The stock gauge isn't very accurate and it also suffers from parallax error if you are reading it off the dash. Get a proper boost gauge if you want to know how much boost it is really running.

The only thing that could cause it to run 14psi without a bleed valve is an old frayed or split wastegate line. This is the hose that runs from the nipple on the compressor housing to the wastegate actuator, if it is split it wil be acting like a bleed valve, this could be a disaster as if it comes off completely you will run 'infinite' boost popping your turbo and possibly your motor.

So things to do:

Check the wastegate line is not split or old. If in doubt replace it, costs $1 for a piece of vacuum hose.

If nothing changes get a boost gauge, or go to a performance workshop and get them to hook one up on the dyno, verifying how much boost you are actually running, eg 14psi spike then 10psi at redline, or 14psi the whole way etc. If it is the later you need to fix it.

Get a FMIC

Get the car tuned via a nistune daughterboard or an aftermarket ECU so that the extra boost actually makes more torque.

[Ruxis]

alright ill have a look tomorrow thanks alot.

i dont want a fmic because its a pretty obvious illegal defect. im not to keen on spending money on an ecu and tune either, id just like it to sit nicely on 10psi and thats as far as i want to go with mods atm as im buying a house next year.

i think i will take it to a dyno though

thanks for your help and time mate

[Rolls]

alright ill have a look tomorrow thanks alot.

i dont want a fmic because its a pretty obvious illegal defect. im not to keen on spending money on an ecu and tune either, id just like it to sit nicely on 10psi and thats as far as i want to go with mods atm as im buying a house next year.

i think i will take it to a dyno though

thanks for your help and time mate

Nothing illegal about a FMIC, no issue what so ever.

[pipster11]

you've kinda got a stock setup with the solenoid bypassed

but if there is no restictor running to the vac side then it will bleed off too much air (dropping the pressure that the wastegate sees)

get a jet lighter and some solder and solder up the vac side of that T, the drill it out with a small drill (maybe 1.5mm)

if the boost you get is too low, go to a bigger drill size

NO NEED FOR ADJUSTABLE WASTEGATES

[Ruxis]

What If the solder cracks into 1,000,000 pieces and goes through the lines??

[Ruxis]

Nothing illegal about a FMIC, no issue what so ever.

really? i thought you can get defected for it?

[pipster11]

What If the solder cracks into 1,000,000 pieces and goes through the lines??

its like 60% lead, which is ductile so its pretty unlikely to crack

you could also steal the restrictor from the stock boost feed line (has yellow bands on the end)

[Rolls]

really? i thought you can get defected for it?

Nope, your car already has an intercooler, it is just a bigger one, why would it be illegal?

Edited October 30, 2011 by Rolls

[MBS206]

you've kinda got a stock setup with the solenoid bypassed

but if there is no restictor running to the vac side then it will bleed off too much air (dropping the pressure that the wastegate sees)

get a jet lighter and some solder and solder up the vac side of that T, the drill it out with a small drill (maybe 1.5mm)

if the boost you get is too low, go to a bigger drill size

NO NEED FOR ADJUSTABLE WASTEGATES

If he is running lines straight to the wastegate, then no amount of restrictors can lower the boost, no matter what you do.

Restricting air/pressure to the wastegate will only INCREASE the boost not lower it.

Ruxis, I can come have a quick look over the car soon for you and make sure it's all hooked up properly (Didn't watch the vid) and check that nothing should detonate.

Also, if you paint the FMIC black then it's not likely to be spotted by the police to begin with, so no issue there.

[Rolls]

Painting the IC black looks better imo as well, not a fan of shiny bling car parts.

[Ruxis]

Thanks matt!

Do you live in Wollongong??? I could come over any Thursday Arvo?? save you the drive??