can someone explain all the systems related/necessary for FI?

[CSMsi311]

I'm not entirely sure that is how a wastegate works.

1.) Why would you want to compress the all the air beyond the boost level you want to run. Thereby, heating up the air more than is necessary; just to vent the excess boost to the atmosphere?

Wouldn't it make more sense if you limited the turbine/compressor speed to limit the amount of boost that you run. Then you only compress the air you are going to use and you avoid adding unnecessary heat.

[SI02civic]

sorry that's what i was trying to say.... a wastegate is a valve used to bleed off excess exhaust pressure on the turbine to maintain optimal boost pressure without over-spinning the turbine wheel.

[andy]

Originally posted by CSMsi311
I'm not entirely sure that is how a wastegate works.

1.) Why would you want to compress the all the air beyond the boost level you want to run. Thereby, heating up the air more than is necessary; just to vent the excess boost to the atmosphere?

Wouldn't it make more sense if you limited the turbine/compressor speed to limit the amount of boost that you run. Then you only compress the air you are going to use and you avoid adding unnecessary heat.

The wastegate helps bleed off the extra pressure because there
is no (easy) way to control turbine speed. The turbine speed
is a function of the speed of your exhaust gases - higher engine
RPM = higher RPM on the turbine. So the wastegate gets you
around that.

Someone else asked about a boost controller...these range from
very simple ("manual") ball and spring type devices to AI fueled
electronic devices. They essentially keep the wastegate closed
by controlling how much pressure it will open at. With the
boost controller on my WRX, it connects directly to the wastegate,
and will only allow it to open when the spring in the ball/spring
valve can't hold it in. Hence the term manual - because you set
the spring rate by tightening a bolt/screw.

I'm not entirely certain how Electronic BC's work, or how they
work in non-wastegate situations...

This month's Sport Compact Car had some pretty interesting
articles on turbos (in particular, compressor efficiency maps), but
it's not the overall coverage that the Maximum Boost book offers.