Variable Compression, Variable Displacement you decide

Gary Derian gderian at cybergate.net
Wed Feb 18 18:25:40 GMT 1998


Any time air flow is throttled, there is a loss in efficiency.  An atmo
engine at part throttle has much higher bsfc that at full throttle.  A
supercharged engine at part throttle, throttles even more and is less
efficient to a greater degree.

Gary Derian <gderian at cybergate.net>


>>  The reason a supercharge is generally
>> less efficient is that they compress more air than is needed, and
substantially
>> increase the pressure in the intake more than is necessary.
>
>I don't understand this point. I thought more air (higher boost) was
>always better. You have more air, so you add more fuel to keep the right
>AF ratio, and vroom! More power :) If you are talking about this from an
>efficiency point of view, I understand then :)
>
>Andris - mech E student struggling with Heat xfer at the moment




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