[Rhodes22-list] Stupid people tricks

[Christine Allison]

<In effect, any 4-cycle engine is also partially "oil-cooled", a
> property which 2-cycle engines do not have.>


Quite a bit of study has been done in respect to this issue as it respects
model aircraft engines.  It has been discovered that a good deal of cooling
occurs when the fresh fuel/oil mixture is inducted into the engine.  In fact
it is this cooling property that mandates the presence of a glow plug.  In
the case of model aircraft purpose designed four stroke engines there is no
separate oil supply.  The oil is mixed with the combustible ingredients
inducted and exhausted at the proper times in the cycle just like a 2
stroke.

The principal advantage to any 4 stroke engine (vs 2 stroke) is the fact
that the cylinder is purged of the spent combustion products resulting from
the prior power stroke before inducting the fresh charge.  In other respects
a 2 stroke engine, operating at it's most efficient RPM will produce more
power for it's displacement then an equivalent 4 stroke. Very simply a 2
stroke has less internal friction and can burn more fuel per revolution of
the crank all that equates to power.

It is not unusual for a 2 stroke engine displacing 6./10 inch to produce
more then 1 hp at its power peak.

However it is true that the oil, acting as a sink,  in a 4-stroke outboard
engine is responsible for a large percentage of the cooling.burden.

Richard Smith