I'm not anywhere near needing a preheater for my Sonerai project, but I have
thought about it. When the day (or decade!)comes, I might try using a
propane bottle, the kind you can buy in the hardware store for a couple of
bucks. It would be below the cowling, far enough away to ensure that the
flame doesn't get too close. Then there would be a duct of lightweight
insulating material to guide the warm air through a door in the bottom of
the cowling into the engine compartment. The torch nozzle might have to be
customized to get the best heat transfer to the rising column of air.

The advantages of this would be a) it's cheap, b) it doesn't require
electricity, and c) it's portable, so I could take it with me on
overnighters in cold weather.

As I said, I'm nowhere near testing this idea. Try it at your own risk.

Ed


"Michael Horowitz" wrote in message
...
I'd be interested in any schemes you may have developed for
pre-heating your engine.

One idea I heard was to use flex ducting to direct car exhaust into
the cowling; that does present CO concerns, but on could leave the a/c
doors open. - Mike