Hi Roy
On (14 Sep 97) Roy J. Tellason wrote to Jim Dunmyer...
 JD> Excessive weight, hard starting when they're cold, noise, and 
 JD> smoking.
 RJ> I can understand the smoking,  and the hard starting because you're
 RJ> dealing with a lot higher compression there,  but I don't understand why 
a
 RJ> diesel engine should be that much heavier,  nor why they're so darn 
noisy!
I don't know why either but here's my guess: the noise is due to the fact 
hat
the instant of explosion, is uncontrollable: the BANG is determined by the
flame propagation quickly after the air/fuel mix has been compressed.
What is then lacking, is a way to advance or delay the BANG to suit desirable
levels of noise/ torque/ gas scavenging+ exhaust emissions. The gas engine of
today with automatic vacuum and centrifugal advance + retard, has a better
chance of being quiet. At light throttle or high rpm the spark [and 
xplosion]
are advanced.  At high throttle or low rpm these are delayed. Overall these
auto controls give quiter operation, better fuel efficiency and cleaner
exhausts than with an uncontrolled distributor.
The noise of a diesel, so called diesel- knock is I guess a result of the 
ery
large conn rod forces. The engine *seems* to be consistently suffering from
"pinging" ie preignition [gas engine terminology].  Cheers....ALEC
... ......All in all you're just a nother brick in the wall [P F Lloyd]
--- PPoint 1.92
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