On Tue, 09 Dec 2003 02:29:34 +0000, F330 GT wrote:

Rod McInnis" wrote in message
...

"Lawrence James" wrote in message
nk.net...

50hp is 50hp.

Not exactly.

What gets you moving is torque. Horsepower is torque times RPM.

In many cases, a two cycle engine is capable of running at a higher RPM.
If
you can get 10% more RPM out of an engine, you can often get 10% more
horsepower. That doesn't mean you can use that horsepower. If you can't
get the engine up to that extra 10% it will never be used. Unfortunately,
it was at that higher RPM where the engine earned its rating.

If there is a concern about getting on plane, then low end torque is king.
This is where 4 cycles usually have the advantage over two cycles. On the
other hand, if you can get planing okay, and need the best top end, 2
cycles
usually come alive at the higher RPMs and can provide more top end.

Rod McInnis





Two stroke engines have always made more low end torque, both motorcycle and
marine. For one reason because the spark plug fires every revolution instead of
every other.


Nice theory, but it hasn't been my experience. My RD350 (2-stroke) had
"toggle-switch power" - wimpy as hell under 5000, then...HANG ON! OTOH, My
Virago (4-stroke) has lots of low-end grunt at 2000, and tops out around
6K.

I think is has to do with efficiencies - a 2-stroke doesn't run well at
low rpm.

Lloyd