mattski2

With the recent fitting of the Defi's the boost meter is set to peak at 1.3 kgf/cm2 (is 1.0 kgf/cm2 1 bar?) - is this overboost? The reason I ask is that before I had the HKS Hiper fitted the car was running @ 16psi boost as it was...

If it is overboosting how can I stop it and what damage will it, potentially, do?

ta,
Matt

[Edited by mattski2 - 5/16/2002 10:13:06 AM]

EvoRSX

MAttski,
1.3 kgf/cm2 = about 18.5 psi so that's a lot of boost you're running.....

1 kgf/cm2 = 0.9807 bar

Andy

mattski2

eek! although I guess that makes sense considering it was 16psi before the exhaust.

question is, will it do any harm? if so, how can I reduce the boost?

I run the car always on optimax + NF and admittedly, it does feel fast as **** ...

ta,
Matt

john banks

In colder weather it will possibly oscillate. The only time I have heard my car detting was when it overboosts with silly peaks. If a late car, increasing the size of the restrictor helps.

The ECU is still aiming for the same held boost.

Dave T-S

Matt

18 psi? - pah - wait till you've tried 25psi (1.7 bar) on an STi7

mattski2

thanks chaps - so it's nothing to worry about then? - just healthy?

john banks

Sorry I am puzzled from your post if you are actually hitting 1.3 bar or not or you are just setting your boost gauge!

Risk of detonation. Right scared you now. You are best sorting it out really especially when it is so easy. When the turbo is hot on a cold moist night it could go sky high - it is out of ECU control - fuel cut and pull back are often delayed enough to be able to see silly boost for long enough to potentially do damage. It will also feel nasty if it goes really high as it may oscillate. At that point it has probably also fallen off the end of the maps and is merely guessing ignition and fuelling based on last known good. You cannot rely on the ECU pulling the timing or adding fuel to stop such sudden detonation - it seems too quick to catch. Yes I am being cautious. That way you keep your engine.

[Edited by john banks - 5/16/2002 5:27:59 PM]

mattski2

hmm, det

O.K... so what are the options to 'fix' it then?

ECU Tek ECU?
Other bits and bobs?
Fuel Cut defenser?
Uprated fueling?

ta
Matt

john banks

Sorry I edited my post as I laid it on a bit thick about det to get you to sort it but then thought you were just setting your boost peak on your gauge??! Still puzzled - are you actually peaking 1.3?

What model year is your car? I had this issue after a downpipe on MY00 - increasing the bore of the restrictor off the turbo outlet by 0.1mm fixed it.

[Edited by john banks - 5/16/2002 5:31:20 PM]

mattski2

well - I've set the peak on the Defi to 1.3 kgf/cm2 and it does peak at that - I may set to 1.4 and see if it does it then. (it's obvious when it peaks, it has an external indicator on it!).

The car went on PE's rollers in January and was running 16psi boost then, that was just with a Scoobysport downpipe and catted centre and prodrive backbox. Since then it has had an HKS Hiper fitted.

What do you think is the best course of action John?

ta,
Matt

oh - Car is an MY99 RB5 WR (Prodrive ECU and intercooler piping). How did you increase the bore of that pipe?

[Edited by mattski2 - 5/16/2002 5:32:45 PM]

Homer Simpson

Just so you know.

On my MY99 UK car, the Defi's were over-reading!

The maximum boost on my car was 1.3 bar, but the gauge was reading 1.4 kgf/cm2, and peaked at 1.5/1.6 kgf/cm2 at points (max reading recall, depending on weather)

I had the gauge tested, and at 1.3 bar, the gauge read 1.4 kgf/cm2.

It can be confusing. Might be worth getting a KnockLink just in case!



[Edited by Homer Simpson - 5/16/2002 5:39:15 PM]

john banks

I suspect if your gauge is quick enough you will see it peaking, pulling back below held and then settling, which feels quite disappointing. On a PPP that level of boost is not quite such a problem - but it will oscillate at some point. You can get a miniature drill kit from Maplin for a few notes with a 1.3mm drill bit in it. Run this through the brass restrictor in the pipe off the turbo outlet. Only problem is that I could never get it spot on and bought an adjustable restrictor valve to replace the restrictor. I did a load of old threads about it in the FAQ thread that was started a while back Flow control valve replacing restrictor

You could also fit a Dawes if you want - controls boost far better than a downpiped PPP usually.

Edit- Homer my gauge was the other way so I was wondering why it was not running enough. I though Defis were posh gauges

Best checking it with a Select monitor or Delta Dash then you can floor it in 4th or 5th from 2000 RPM and plot the boost curve.

[Edited by john banks - 5/16/2002 5:40:28 PM]

Homer Simpson

You're probably only hitting 1.2 bar. Which is about 17.5psi (I think)

When I ran my car with a PPP ECU and a full Scoobysport exhaust, it was peaking at 18.1psi (according to a select monitor) but the overboost cutoff didn't kick in.

That said it was a very cold day when we tried it out!