When does it boost?

[AlfaJack]

Hi,

Just a curiosity, my Q4 does not boost unless I am driving it.

For example, If I rev the engine whilst at a standstill etc, there will be no boost - and no whoosh from the dump valve, but when I drive it, the boost is normal. Some friends with turbo cars, their engines boost when just sitting there, should the Q4?

[Jarkko]

you wil have to pump the gas more ! and almoust to the redline too. done that with standard t-3 and also gt40 garrett, both works

[Brul(tm)]

Jarko is right
I too get the woosh while standing stil, but why would you
It's an Italian car

Greetings,
Marc

[AlfaJack]

Jarko is right
I too get the woosh while standing stil, but why would you
It's an Italian car

Greetings,
Marc

Its strange, because, noticeable boost noise is achieved at 3000 rpm when driving, but when stationary its like a normal engine when reved to 3000, perhaps it just needs to be under load to tell the ECU to provide boost - its not that I want to to do it, just wondered why it doesnt do it

[wrinx]

This confused me for ages when I was sorting the boost out on mine...on the drive...stood still

Someone helpfully posted there's no boost until you're moving, problem solved

wrinx

[q4fatboy]

I have never managed to get mine to boost whilst stationary, a quick run up the road is always required.

What about the neighbours you say, heh noisey cars are normal round here

[veki]

I also have no boost when stationary.

When you launch the car from 3,5 - 4000 rpm, there's plenty of boost, right? So my guess is that it has somethyng to do with the fact that the engine is not, what's the word, burdened.

Can someone say whats the reeding, since I dont have a boost gauge.

Turbo blows for shure, because of the exhaust gases, and the ECU cant influence that.

[Steve Webb]

Yes the boost produced is a product of both RPM and the load the engine is under\duty cycle of the injectors.

I can get a small amount of boost at standstill by revving the car in a 'boy racer fashion' between 1500rpm and 4000rpm, not a very sociable thing to do and you only get a small amount of boost.

The way the WRC and other rally cars get boost whilst stationary is by using something called an anti-lag system (ALS) or Bang Bang system. These use an injector firing fuel into exhaust manifold BEFORE the turbo. The fuel ignites \expands and spools up the turbo without the need for any load on the engine. Noisy and doesn't do the exhaust system any good.

Steve

[j1v]

The way the WRC and other rally cars get boost whilst stationary is by using something called an anti-lag system (ALS) or Bang Bang system. These use an injector firing fuel into exhaust manifold BEFORE the turbo. The fuel ignites \expands and spools up the turbo without the need for any load on the engine. Noisy and doesn't do the exhaust system any good.

Steve

Actually these were the very first ALS systems. Now they are using sophisticated systems, that control the advance and with very late ignition of the fuel the burning continues out of the combustion chamber in the exhaust manifold, and that's how they accomplish boost without load (for gear change and launch control)

[Steve Webb]

Damn, I must be getting old. Makes sense to do it the new way though. Cheers for enlightening us.

[Brul(tm)]

Its strange, because, noticeable boost noise is achieved at 3000 rpm when driving, but when stationary its like a normal engine when reved to 3000

I need to correct something
The actual boost (extra presure) is only available whilst drinving or under load, but I am able to get the Woooossssshhhhh noise while reving and standing stil. You need to build the gasflow, it's posible.... But again, why would I want that

Greetings,
Marc