Tim Wescott wrote:
Grider Pirate wrote:
On Mar 14, 11:30 pm, durabol wrote:
Thanks for the responses. I meant for ultralight or light aircraft
with 20-40hp from 1 or 2 cylinders. I definitely want to copy as much
as I can since I'm not engineer. I planned to have the RPM at about
4000 in order to get enough power out of the engine but I may reduce
the rpm if I can get enough power. Also I may have to weld the crank
together to handle the propeller loads.

Brock

'Restrictive' exhaust isn't a good way to avoid venting unburnt fuel,
and it will really clobber performance. If you're really trying to
get good performance, especially over a narrow band, then you really
need to consider using tuned pipes (AKA "Expansion Chambers"). Gordon
Jennings "Two Stroke Tuners Handbook" covers most everything you need
to design a two-stroke.
4000 RPM is pretty low for a two-stroke. The tuned length for the
pipe(s) would be around 6 FEET.

Ship's two-stroke diesel engines top out at less than 200RPM.

I don't think they use tuned pipes, but if they did I suppose they'd
have room.

Don't need them. They all have massive
blowers for scavenging.

I believe EMD built locomotive 2-strokes that
had a set of exhaust valves in the head and
a blower port that was opened at the bottom of
the stroke. No tuning, the blower was plenty
to force out the exhaust and fill the cylinder
with fresh air.