How high can the boost on an STi (classic) be wound?
 

I've got an MY99 Type RA STi (Still makes me grin everytime I type it :D)

Standard boost is almost 19psi. How high can this be safely wound up to on an STi?

seams a bit high for standerd, is that correct?

I think it is, aren't they somethin' like 1.27 bar standard? My SECS is reading peak boost as 18.6 psi.

It is a bit high for standard to be honest.

1.1bar should be nearer the mark.

I hope it's run on Optimax at least and preferably with a booster at that kind of boost and I also hope there's a knocklink on there too.

If not, you might well be looking at a rebuild in the not to distant future because if thrashed it will probably be detting.

Re safety.

The boost you are running now is unsafe IMHO unless you have a knocklink.

So certainly do not wind it up more

He does have a Knocklink and uses Optimax + OB.

The boost deos sound a bit on the high side. Are you sure there's no mbc/bleed valve/smaller restrictor?

Standard boost target is 15.7 PSI. A suitable overshoot is up to 17 PSI when thrashing it in a high gear on a cold day when the car is hot.

SECS reading clipping - the Select Monitor Protocol is uses saturates at 1.27 bar or 18.4 PSI. So you are probably running more.

The boost can be wound up to about 22 PSI safely on a standard STi engine but not on anything like standard spec. If you want to take less of a risk, 19 PSI is a good bet. But only with the right breathing and fuelling/timing.

Ok, thanks for the input guys.

Yeah I do have a KL, though she's running on SUL + OB. Very little activity on the KL and I'm perfectly happy that the KL's fine as you should've seen it pre-MAF change. Under very heavy thrashing I normally get both greens lit.

There's no dawes or bleed valves fitted, and I don't believe that the ECU has been remapped at any time.

I'm gonna reset the peak values in the SECS and watch it, mayb it's a value it's picked up itself.

My main reason for asking was I'm planning on getting her remapped for uk fuel, so I was gonna get the boost raised at the same time. Seeing as it already seemed pretty high I wondered how much higher it could actually go.

Thanks again.

Well the engine mapper should have a value in mind when he sees the car and talks to you about you needs!

A mate is running 1.4bar mid-range and tailing off at the top..
just as an example.

JGM :)

Not the same year, but my v3 Sti with decat has a Blitz boost controller to stop over boost/fuel cut, and is set at 1.31bar, it crept to that reading from 1.25 and is now steady. I run on staight Optimax, thrash the death out of it in competition hill climbing for 2 years and all is well.