RICH WILD

Hello People,

I've just fitted a Turbosmart bleedvalve, despite the warnings and I have a few queries.

Took the car (96UK) out, increased pressure gradually checking boost in 5th each time. Got to 14psi peak no probs, then turned bleedvalve quarter turn and did same again.
The car flew, boost went past 15 peak, but not much. BANG. Almost like blowing a hose, like the car had coughed.

After cleaning my pants I turned the bleedvalve back a bit and no probs.

I PRESUME I'd hit the overboost sensor on the standard ECU and it had cut the fuel????Is this likely?

Now how do I get round this? I've been warned about lean running, chocolate pistons etc. but I'm getting an air/fuel meter so I can keep an eye on it.

If I up fuel pressure (power boost valve) will this help? Will I still have the ECU slapping my wrist? is the only option to fit a superchip to remove the overboost limiter??

Please advise me as I haven't got a clue!!

I hear all these guys talking 20+psi and I want to be in your gang!!

Cheers
Rich

Adam M

Sorry mate, I dont know enough to answer your question , but when you say the words havent got a clue, alarm bells ring in my head.

You are taking a risk just to save yourself money, which the way you are going about it, is likely to cost you more.

The guys running 20 psi, are taking a risk too as no one knows how long standard internals (if they are standard) will last at that pressure. Safest way to do what you are trying is to get a link fitted and mapped by bob rawle. It may cost more now, but it probably won't in the long run.

And you get better fuel economy!

20 psi can be fine depending on what else is running at 20 psi. If you have a better intercooler and water spray and injection , along with a more efficient turbo, then 20 psi is much safer than if you run it on a standard car.

Its your choice, just be careful!

GavinP

Rich,

You did indeed hit the fuel cut at 15.5psi.

It is a VERY bad idea to disable the fuel cut and then whack the boost up - if you want higher than 15psi, you need to be looking at a Unichip or Link (for the control over fuelling and ignition timing).

Lee's site

scoobycar60

Rant on
Bleed valves are a load of rubbish ,I know believe me I toyed with them for years they appear to offer a lot on the surface but will result in very erratic results that WILL destroy your engine.Give yourself a sporting chance and speak to Bob or someone who can offer a safe ecu map.
Rant off
Sorry bit strong but I,m peeed off at the moment as I've just blown my own engine up....

steve McCulloch

Rich Wild

email me off line and I can talk to you about the subtleties of engine mods

I have had bleed valves before! - and my Scooby aint a patch on my previous car!

Take the bleed valve off immediately and consult Uncle Bob for a nice powerful, safe map that gives increased fuel performance!

RICH WILD

Cheers guys,

thanks for your advice. I think for safety's sake I'll leave the fuel cut alone.

Gavin, I've noticed that about the valve that the peak can vary by 1 or 2psi on certain days. But now I'm confused.

If cold air is denser than warm, you'd expect atmospheric pressure to be higher on cold days as the air is denser. Therefore on cold days, there is more resistance to bleeding due to high pressure so the boost pressure will drop??
Is this true or am I talking Bollox?

If this is the case, why do we associate hot weather with high pressure weather systems and cold weather with low?

Any ideas?


Rich

Blackscooby

Ran a bleed valve in 1999 on a UK94 for the Harewood Hillclimb championship.

Blew a piston....total engine rebuild.
What cost me £30 for a bleed valve in the end cost a **HUGE** amount of money.

Won't say how much boost I was running at the time cos you'll all laugh....

dowser

"The lights go green, the Scooby screams away leaving the 600bhp Porsche turbo mkXI struggling."

"The Scoob grabs second 20 metres ahead of the Porsche.....but wait, what was that loud 'bang!'......what's all that smoke........"

GavinP

Boy, there are some strange ideas running in this thread....along with some pretty sweeping generalisations!

Speaking from personal experience on an Impreza, it does work and is safe provided you are sensible and leave the boost cut alone. I increased the boost on my car from 12psi to 14psi in exactly this manner using the Turbosmart valve.

The standard JECS ECU map certainly covers upto 15psi so it is working within known parameters.

Bleed valves do vary according to atmospheric pressure and temperature so are not ideal in that respect but used sensibly they are not the "ticking timebomb" that some people seem to think...

The only instances of Impreza engine blow-ups I have heard of are when using bleed valves when the fuel cut has been disabled.

Please do take a look at Lee's site where he goes into considerable detail about using it on an Impreza.

Having said that, both Lee and myself both now have Link ECUs to run higher boost. Once you get a taste - you want more....

Thanks

Gavin

[This message has been edited by GavinP (edited 07 June 2001).]

GavinP

Rich,

I'm not sure on the "hows and whys" of the atmospheric pressure but I know it makes a difference!

What you will notice using a bleed valve will really hit your fuel consumption. My car certainly became much thirstier after I fitted one.

After Bob fitted and mapped my Link ECU, the fuel consumption was better than with the standard car and the torque increase was very impressive.... another good reason to sort the ECU

Thanks

Gavin

scoobysnacks

If there's a fuel cut a 15.5 psi, then why do some unmodified cars in the dyno section hit 16, 17 or even 18 psi on some runs?
Anybody know what psi a standard 98 WRX will boost to before a fuel cut (or damage) will occur? Does the automatic fuel cut always stop damage to the engine, and therefore are bleedvalves safe if you don't remove this protection? Thanks for any answers.

GavinP

SS,

I'm not sure where the fuel cut is on later models - I know that 94-96 cars are 15.5psi.

I know boost was increased on later models but I think (?) that this is only on MY99/MY00 models. I'm sure someone with a MY98 will be able to answer your questions regarding the fuel cut for the particular model year.

As long as the car has an ECU with a map for the boost level you want to run, you should have no problems. The fuel cut is effectively telling you that the boost is too high for the ECU to handle and hence why disabling this "safety net" is VERY bad news.

Exhaust modifications (downpipe especially) can increase the boost level as you can see from the dyno site.

Subaru dealers adjust boost levels by using restrictors with different size holes in them within the wastegate pipework. This is basically what you are doing with a bleed valve (although you are allowing a small amount of air to escape).

Thanks

Gavin

AlanG

Yup MY99 can hit 18psi before fuel cut but only if it stays at 18psi for a couple of secs. In other words, hit 18 psi , no problem, hit 18 psi for a couple of secs.....ouch ma heid!!!

A

AndyMc

Hi

For info on my UK MY98 the boost cut is about 16.5-17psi.Thats assuming my boost gauge is accurate. (Don't know what it would be on a WRX but suspect it might be a bit higher)

Andy



[This message has been edited by AndyMc (edited 08 June 2001).]

MTR

Hello all,
According to my local Subaru mechanic, the boost levels for post 97 cars is 13.1psi, and for P1's its 15.95psi.
These are not fuel cut off figures but the recomended running max boost figures.
The fuel cut of figure for the later cars is 17.4psi.
He didn't tell me what the cut of figure is for the earlier cars.

They should have a 1.5mm (0.9mm in the P1)dia hole in the brass restrictor in the wastagate piping near the T piece in the pipe going to the engine.

MY MY00 with STi5 centre pipe and PPP back box everything else std, pulls 14.1/14.3psi approx peak, although it chnges so quickly on th escreen you can barely read it, 13.8psi held, checked by myself today with the select monitor. But the restrictor in my 3 month old car is 1.1mm !!! for some reason.

Go figure.

Edited to remove figure for the pre 97 cars as I think I scribbled them down wrong from his notes whilst I was talking to him.

I have got a figure of 14.5psi written down for the earlier cars and I summise that must be the fuel cut figure?
I will have to check more carefully next time I speak to him.

Cheers MTR

[This message has been edited by MTR (edited 09 June 2001).]