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Old 06-08-2013, 01:51 PM   #391 (permalink)
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throttle plate

Originally Posted by steffen707 View Post
There's also a big gain from having the throttle plate open further at a given speed, because it reduces pumping losses from the engine, I'm not sure how to explain that, but this thread has good info on it.
*Yes,the throttle plate is like a sheet of plywood,flat into the airstream at low throttle settings,with Cd 1.11.Ouch!
*At wide-open-throttle the Otto-cycle engine approaches the volumetric efficiency of a Diesel,lacking only the 10-11% Btu advantage of the Diesel fuel itself.
*Gasoline Direct Injection engines dispense with the throttle altogether,running at WOT just as with a Diesel,doing all the fuel metering with the electronic fuel injection.
*During the era of the 55-mph national speed limit,some car makers (HONDA) designed their carburetor's 2nd barrel to operate at WOT during cruise,with the 3rd barrel for passing and climbing,achieving mileage like today's hybrids.

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