"RG" wrote in message
...


Hmmm. I'm the originator of this thread. I've posted the same query at a
number of boat/motor sites. The results were, at my last count..27 to 3
....
two stroke over 4 stroke.

I was specifically addressing the statement that "HP is HP". There are
other reasons that a 2 stroke might be better than a 4 stroke.

2 strokes, in general, weigh less. On a very small boat, such as an
inflatable dinghy, this can be the overriding issue. As the size of the
boat increases the weight factor is not as important. Also, as the size of
the motor increases the weight difference becomes less.

Recent advancements in small engine 4 strokes (outboards, motorcycle, etc.)
have managed to make lighter weight 4 cycles. The pressure to improve the 2
cycle emissions has made them heavier. The result is that the advantage of
2 cycles has dimenished somewhat.

Rod, is there any study, etc. that speaks to the "better thrust" factor on
4
strokes that you mentioned?

I can be more general in this philosophy.

Whenever you compare any two engines, look closely at the HP specification.
The horsepower should have an associated RPM that the horsepower was
measured at. If Engine "A" is rated at 50Hp @6000 RPM, and engine "B" is
rated at 50Hp @ 5000 RPM, engine B is going to out pull engine A in a tug of
war.

When thinking horsepower, think thoroughbreds verses clydsdales. A
thoroughbred is fast but it would never pull a plow. A clydsdale isn't
going to win any races but they can pull tree stumps.

Rod McInnis