One thing that you overlooked. Using your lever example, a short lever takes
a lot of force over a small distance; to lift the same weight with a longer
lever will require less force but over a longer distance. These two lifts will
require the same amount of work(energy).
Theoretically the car may run a bit cooler, but the only reason is you are
slowing
the engine RPMs down so the recipricating assembly is moving slower, creating
less friction (than at higher RPM), and you are firing the cyls less often,
generating less heat. However I really doubt it will make a difference. The
more important factor would be the efficiency of the cooling system. One test
this is to get stuck in traffic on a really hot day; your radiator will probably
get to near boiling after a little while. Now, go jump on the highway and drive
at 5000RPM and you will see the gauge start dropping immediately. This isn't
scientific, but the point is the airflow to the radiator, and the efficiency
of the coolant and the radiator are far more important than the engine speed.
The primary reason for lower RPMs is the reduced noise, and the reduced guilt
factor of running an engine way up in its revs. I don't even consider bearing
wear to be a factor in a healthy engine.
--
James Nazarian Jr
71 MGB roadster
71 MGBGT-V8 in need of paint
01 Impreza 2.5RS
A complex system that does not work is invariably found to have
evolved from a simpler system that worked just fine.
On Tue, Jul 03, 2001 at 08:56:50AM -0400, Edwin McCarroll profoundly declared:
> Reference Gerard Brinkman's comments on the 5 speed installation in an MGA.
>He disagrees with the view that an engine turning less rpm's will generate
>less heat and maintains that changing the ratios in the box will not affect
>this aspect. Intuitively I think that the mechanical advantage inherent in a
>five speed with the improved ratios over those of a 4 speed box requires less
>effort (less energy) and is an efficiently improved system when required to
>propel the car at any given speed. I had been thinking that the principle of
>levers might apply in thinking about gearboxes inasmuch that a short lever
>used to lift a given weight requires more effort than when using a longer
>lever because of the mechanical advantage. Doesn't this apply in the gearbox
>comparison discussion? Doesn't less effort expended to move the car a given
>distance at a given speed require less energy through mechanical advantage?
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