Re: [MV] top speed of an M35

From: DDoyle9570@aol.com
Date: Wed Sep 26 2001 - 18:47:35 PDT


In a message dated 9/26/01 7:45:42 PM Central Daylight Time,
jnewton@laurel.com writes:

<< I did remove the "governor" and did not notice that much improvement
 in towing capacity uphill, which is what I was really hoping for.
 
 You won't over-rev your engine if you watch the tach...I never let it
 go above the danger area EVER.
 
 Propane would not over-rev the engine either...it produces more
 horsepower and torque at any given RPM...it doesn't increase the RPMs. >>

While I will concede I left engineering school long ago, and before
graduating, so I can't classify myself as an expert. However, the problem
with engines is not the revolutions (as I am sure our fellow lister who
builds racing engines will likely confirm), the problem is the stresses
within the engine....when the piston reaches TDC (the sudden stop, and the
piston does completely stop twice each revolution, tries to pull rod into,
top off piston, etc) there are tremendous tensile stresses placed on the rod,
and at BDC you will have large compression forces on the rod. Both of these
also try to bend the crank. Failures will tend to originate at ANY
imperfection on these components. This is why various moving components of
high horsepower engines are polished and plated, to remove these
imperfections where stress cracks begin.
Even if you do not increase the RPM of an engine, if you increase the
horsepower you inherently are increasing the stresses inside an engine.
The rods and crankshaft of an LDT are designed for a maximum of 205 brake
horsepower (this is only because these components are shared with the
LDS-465-2), REGARDLESS of how that horsepower is gotten. Beyond that you are
second guessing numerous professional engineers whose livelihood depended on
their success.

The governor on a multifuel engine doesn't directly control the speed, it
controls the fuel flow based on speed. The higher the RPM the engine is
turning, the more fuel it will allow to be supplied. When you defeat the
governor, it seems you would defeat the natural tendency of the engine to
protect itself by choking to death. Rather, it will continue fueling in an
effort to keep its RPM up, this will allow more fuel into the cylinders, and
if it can be burned efficiently, results in more horsepower. Horsepower can
be expressed as heat (2545 BTU/Hr as I recall). So, the more fuel, the more
heat, the more horsepower, and the MORE STRESS on those rods and crankshaft,
regardless of RPM.

So, to make a long story short, if you don't plan on polishing and plating
any of your LDT parts, but you do plan on "souping up" your engine, go now
and buy a spare to drop in its place, you'll be needing it.

My .02,
David Doyle



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