All this talk about engine mods has me thinking about an interresting
formula proposed by Dr. Fred Lanchester in this months issue of
"The Classic Motorcycle" Fred says that there's an upper limit to the
speed at which any engine can rotate without self destructing, and here
it is:
RPM Limit = 4000/( S x .00656 )
S equals stroke in millimeters
At a sustained spin of "RPM Limit" the engine will certainly suffer
broken rings, pistons, connecting rods etc. The formula considers the
inertial loads of a piston at a mean speed of 4000 feet per minute, and
assumes normal steel and aluminum forgings and castings. Most manufacturers
allow for a 10% tolerance in their redline specifications.
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