2-strokes are only really a consideration as preferred powerplant in smaller aircraft.  This is because they have by far the best power-to-weight ratio of all engines.  But you’ll struggle to find any group of pilots pointing in all directions and telling well-worn flying tales who won’t have a few tales to tell of engine-outs and other 2-stroke cautionary tales.

This sentiment is echoed on all the web forums, as builders continue the quest for a more reliable, quieter, more fuel efficient engine (the gaze always turns to the 4-strokes).

But if weight is a prime consideration, and you can live with the noise and the possibility of an engine-out – then you have to consider these…

There seem to be only three major contenders in the 2-stroke arena:
Compact Radial Engines:
http://www.compactradialengines.com/mz202.html

These engines are engineering marvels – and come complete with gearbox and clutch. 60hp at only 87lbs is pretty impressive.  But not cheap.  However, they do power the Mosquito ultralight helicopter.  And if you ever want a reliable engine, you want it in a helicopter.  There’s a Mosquito at my local airfield.  It sounds like a mad hornet on crystal meth – but the word is that as far as 2-strokes go, it doesn’t get much better than this…

Simonini:
http://www.simoniniusa.com/

Again, really beautiful engines.  Also complete with reduction drive.  382cc, 48hp, 70lbs complete with exhaust and redrive.  This is a stunning little engine, and at just over $6k it doesn’t outrage the bank balance too much either.

And finally, the venerable Rotax series of 2-strokes:
http://www.rotax-aircraft-engines.com/a_engine_503_447.htm
These are the standard by which other 2-stroke aero engines are compared.  But for some reason (their breathtaking high price?) most people I’ve met who fly behind one would like to move to a 4-stroke.  Maybe it’s just another instance of too noisy, too gas-hungry and just not a 4-stroke?

Polini Thor 250

This stunning little engine (36.5hp @ 7500 rpm) is a work of art.  Specified as standard on the new Belite ProCub.  There isn’t a lot of info on the Polini Thor 250, but James Wiebe has a warts and all review of this engine on his blog.  Well worth the read.  You can read it HERE.

For tech specs, go HERE

If I were to choose a 2-stroke engine, and if 35.6hp were sufficient for my purposes, I would take a long, hard look at this little beauty.  Cost?  I think Belite sell them for $3750 USD