Gear Head

iTrader: (2)

I have a MY99 UK Turbo with stage one mods. Pushing around 275bhp.

The boost gauge usually reads around 14/15 psi peak, settling to around 12/13 psi. Just noticed today that she is only peaking at around 13 psi and settling at 10/11 psi.
I know its over 30 degress today, so i'm hoping its just the weather??
Any ideas?

Chris

Gear Head

iTrader: (2)

Anyone?

Rokay

Ambient air temperatures and pressures of the day will certainly effect the running of an engine. Remember that cold damp frosty morning.

Whooooooosh

Gear Head

iTrader: (2)

Can't believe its still 26/27 degress outside........at 10.40pm!

Gear Head

iTrader: (2)

Anyone else experiencing this problem?

ReggieMY99

Yes my MY99 does the same, bit lower on the boost due to the hot weather, dont worry about it, you'll get your power back when it becomes colder again

jase/karen.v1.sti

The more cold air u can get into that intercooler the better. Scoobys dont like the hot weather!!!!

hectic

Heatsoak.. a pain in the ****, but it should right itself as the ambient temperature decreases

Paul Stab

add water injection, it will restore lost power in this weather by cooling the charge down.

Gear Head

iTrader: (2)

According to Bob Rawle (sp?), water injection is a safeguard, not really a performance enhancer..??

Paul Stab

you want to try it in this weather then

silent running

Water injection is generally considered a last line of defence, a way to keep your engine running at full tune under less than ideal conditions. But of course it is also very handy in this kind of weather we're having.

st3v3

Just me thinking aloud here,
but wouldnt the boost be the same ie:1 bar =1 bar,so the volume is the same but because the charge temp is up,the ECU retards the ignition thus making less power?
Therefor 1bar still=1 bar

silent running

If only the ECU actually DID know anything about the charge temp, or even the ambient air temp... That normal part of modern engine management kind of passed Subaru by. Not quite sure how, because I've not looked properly into it, but on the Subaru, rather than the ECU handling it and commanding a power decrease in hot weather e.g. by retarding the ignition, you end up with less boost. Which is another approach I suppose, and one which seems to work. As I say on my old turbocharged car and AFAIK most others, boost levels are totally unaffected by the weather - your target boost, say 1 bar, is hit but in cold weather it FEELS faster and in hot weather it FEELS slower. On a Scoob, the actual boost level is what changes according to the weather.

At a guess I'd say the Scoob uses the MAF sensor to calculate the volume of air going in, and this must change with the actual ambient temperature i.e. with the turbo spinning and making 1 bar, a certain amount of air must be drawn in at normal air temp. If less or more air volume is measured, the ECU must realise that this is down to different ambient temps, and it then alters the boost target up or down? Just a non-expert opinion anyway.

It is striking the difference in boost levels you can get on cold and hot days, so my guess is that the ECU is commanding boost levels in that way to keep everything right. It has the equipment to do it (in the boost solenoid) so why not?