Waste gate chatter?

[zevans]

Originally posted by Fish
Wastegates are one way of controlling boost, another is air injectors. Ford have been using these for years.

So where do they inject air from / to - and what do they do with charged air they don\'t need?

Inquiring minds wish to know...

The ECU also controls the amount of boost that a car runs.

Yeah via the wastegate solenoids

[Fish]

I had to have this re-explaned to me, as its been some time.

They are quite simple really. A "set" of air injectors consists of two independent units, on one mounting.
 
They need two individual PWM outputs from an ecu.
 
One PWM signal works one of the injectors, which "opens" the wastegate.
 
The second PWM signal works the other injector, to "close" the watsegate.
 
On spool up, the "close" injector keeps the wastegate closed, allowing the best spool up.
 
When you get to target boost, the ECU switches to the "open" injector, to prevent over boost, and then balances the two injectors to maintain the target boost.
 
They are obviously designed to work with an "external wastegate".

Fish

[zevans]

Thus smoothing out all the transitions and getting rid of spikes...

Doesn\'t matter how clever you think the last thing you learned about performance cars was, there\'s always an even more clever thing you don\'t know about, in\'t there?

[Fish]

And this stuff has been used in WRC and such since about \'85.

Fish