I don't know a thing about them, but as soon as I saw the Diamond Twin Star with the 135hp diesel engines I thought how I'd like to put one of those bad boys on the front of my Cessna 140!

Three gallons an hour at 125mph...I could fly a thousand miles on one fill up

Don't know if its a fair comparison, but I have a TDI (diesel) VW Golf, and that 90hp engine will out-climb just about any car on Donner Summit and get 40mpg while doing it. I always thought it would make a great airplane engine.

Anyone hear of people converting other planes to the diesel engine?

You are referring to the Thielert Centurion diesel engine. It is currently certified for retrofit into Cessna 172s and Piper Warriors that were originally equipped with the Lycoming O-320 engine.

It is a 1.7 liter, 135 hp four banger weighing in around 300 pounds, but the displacement is less then 1/3 of the O-320. The positive side is that it achieves max power at 2300 prop rpm whereas the Lycoming reaches max power somewhere around 2700.

The new Centurion 2.0 liter is cranking out 160 hp and is in production now. There is talk that Thielert is planning to certify a Centurion 4.0 liter, 310 hp V-8 this year, but I have not heard anything more about it.

Maule's new M-9 that made an appearance at Palm Springs, sounds pretty sweet.

More info at: http://maulepilots.org/forums/viewtopic.php?t=61