Just picked up my first Impreza, it's a 2001 WRX. I was just wondering when the turbo is set to activate. Does it cut-in when the revs hit a certain amount, or when you accelerate hard, or both? Just wondering so that I can save some petrol when I need to

 

Not sure on the revs, but you dont really "feel" the turbo kick in on these the TD04 is a tiny things with much more progressive spool, due to there being no lag.

If you are trying to save petrol, which is futile in Impreza anyway just try to keep it under 3k

 

Thanks for the speedy answer..... So does that mean the turbo activates whenever you accelerate or only when you accelerate hard? I presume it's all electronicly controlled?

 

It will spool on any acceleration, above a certain rpm.

It is controlled by your right foot mate, the boost is controlled electronically via your ECU and actuator

 

The boost level is controlled electronically...
Is this the first turbocharged car you have owned...?
If so it would probably be an idea if you look in to how a turbo works to understand when it cuts in....
How does a turbo work
This may help.........

 

basically as the revs increase and the exhaust gas flows faster then turbo spinds quicker and makes more boost ( forces more air into the inlet ) the amount of air it can force in ( or rather the pressure ) is regulated by the turbo wastgate so it cant force in too much and lean the mix out too much.

very basic answer but yes, its controlled by how far you open the throttle, it only seems to 'cut in' when the revs reach high enough level to get it to spin fast enough to be effective.

not a great explanation, but probly better than the 1st answer lol

 

Thanks for all the answers guys, this is my first turbo car but I do know how a turbo works

I just really wondered at what numbers of revs the turbo started to spin-up or spun fast enough to become effective. I'd imagine it's around 3K revs?

 

depends on model or turbo fitted ( tehre are so many varients ) but somewhere between 2.8k and 3.2k revs

 

In general the bigger the turbo the higher up the revs it will be before it starts getting up to speed and making boost. The smaller the turbo the lower down in the revs it will get started, but the trade-off is that it can't handle high boost pressures and runs out of puff at high revs.

 

If you listen carefully you should hear the turbo spooling up at about 2500revs from just under 3000 on the TD04 (standard small wrx turbo) it should be able to give you full boost.

This gives a good description of the characteristics of different turbos
AndyForrestPerformance

I did have a link to a page which detailed virtually every turbo you could fit to the impreza range and their driving characteristics, but I can't seem to find it at the moment, anybody...?