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George, there are several diesel attributes that I find less than
desirable, but one of the least desirable is its ability to make baby diamonds
in the oil. OK, not really diamonds but carbon. The carbon is
extraordinarily abrasive, requiring oil changes at very short intervals or a 55
gallon oil sump. Finally, and a little humorous, a diesel does not have a
throttle or spark plugs. Sounds good, right? The only reason a
diesel makes more or less power is the result of turning a "fuel metering valve"
inside the injection pump. I personally have seen a metering valve jam at
full power. The car was setting on the emission lab floor in the GM Test
Lab in Denver, CO. The engineer who started the car panicked, took the
keys out of the "ignition" (term loosely used), threw them and ran away.
While the engine was rev limited by valve float, another engineer went over and
disconnected the fuel supply line. No, it was not me. I was hiding
under a desk. My point......there is only one way to shut down a diesel.
Turn the fuel off. Well I guess if you had a sleeping bag laying around
you could stuff it into the intake. Doing so in flight might be a little
tricky. <grin>
Craig Berland
EITHER WAY - -
- you end up with an ENGINE that may have a BSFC of around 0.36 to
0.37 (compared to 0.38 to 0.39 for a same horsepower spark ignition engine
) .
However - - whatever
fuel efficiency is realized - - - is most likely MORE THAN OFFSET by the
additional cooling drag requirements.
End result - - - it
likely takes more pounds of fuel to get you from A to B - - or more Hp to
get you the same air speed.
Regards,
George
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