I just acquired one and wondered if anyone has tried one for aircraft use. What did you do and how did it work?

The Kolher M 20 engine is a very tough and reliable engine. Heavy engine. There is not much you can strip off of it to lighten it up. Its use in small air boats at first found that direct drive props pushed the crank into the case and caused to much damage or it would break the crank from the acceleration or decceleration innersha torque between flywheel and prop. Kolher does not recomend it uses for any propeller application
Nebr prop buster!

so it must be fitted with a reduction drive?

Chris

That flywheel/fan has got to weigh a ton. I haven't opened it up yet so I'm just guessing. If I do away with the starter and make an aluminum fly wheel to hold the magnet. Get rid of the alternator. Maybe go to dual carbs???

Do that add a reduction drive and strip every ounce of weight and I think you will have a reliable gas sipping engine.

Chris

I have never seen anything like that fly wheel. It truly does weigh a ton.

I guess I can turn the existing flywheel down to it's hub and use that to build an aluminum flywheel on, but I wonder if there's anyone selling a tapered shaft hub out there.

Carburetors

How does one determine what carburetor to use in any given situation?
A pair of down draft carbs would eliminate a lot of funky junk on the top of this engine, and give a little boost in hp.

Greg,
any progress with this engine yet?

Chris

I have not had a chance to mess with it in the last week or so.
I am concerned that it might not be enough to power the MonoFly at the 7500' that I'll be living at in NM.
I'm wondering if I should invest my time in a 4A084.

Greg, A 4A084 would work but might be a little heavy. have you considered a half VW www.betterhalfvw.com or a generac conversion www.culverprops.com I have nothing but good things to say about the generac.

Chris

The stripped weight of the 4A084 is supposed to be about 125 lbs, so it is probably heavier than the Generac, but the potential torque of those 4 cylinders is attractive. I looked at the half VW units (including the Mosler) and they seem pretty expensive and relatively heavy. Still have not acquired anything other than the Kohler.

The 4A084 would be an engine that you could "take with you" to another aircraft and certainly are cheap to acquire

Greg, I was not aware that the 4A084 was so light, the generac weighs 120 ready to fly. By all means use the 4A084 if you can find one cheap.

Chris

I'll bet that M20 is a VERY durable engine. Expensive, too.

I have a similar Onan. Mine weighs 75 lbs with carb, intake, govenor, stator, complete block & heads. WITHOUT shrouds, starter, flywheel, coil, battery, fuel pump, exhaust system, air cleaner.

I am planning to work with it a bit to see how much more low-end power I can get out of it. At 60 ci it seems a better engine to start modifying than something like the 2A042, which has less displacement (42 ci).

I also have a big heavy flywheel, which contains the magnets. Mine looks like I can turn it down on a lathe so that I have left only a much smaller flywheel, sort of inverted bowl shaped. It may turn out to be too heavy, we'll see.

If you are still considering engines, take a look at the Honda GX390. Kart folks use them all the time. Lots of hop-up stuff available. LIGHT engine, for its power.

If I can find one to fool with I want to look over the Briggs 500cc single, although it seems to come in only vertical shaft. It has some kind of integral balancing mechanism. Pretty cheap, 20 hp stock. Pretty light. I am sorta wondering if the 390 after-market cams will fit...

GeoB