OS GT55 Opinions?

[Qmulus]

A few years ago I bought an OS GT55 gas engine that had a scored piston and liner for a project. I got a new piston, ring, liner and head gasket and it is now as new, but I sold the plane that I originally bought it for so now I am trying to decide what to do with it. It is just sitting in box... I know it was a fairly expensive engine, possibly sensitive to overheating (hence the scored piston and liner I would guess) and would often start backwards due to the ignition used. I did buy a RCXP ignition for it hoping that would get rid of the starting backward issue. From the looks of it, the quality of the engine is excellent. The crank is a work of art and the casting is beautiful. It must have a pretty high compression ratio, as it has noticeably more than the DLEs and EMEs that I have or had.

My question is, for those who have had one, is the OS GT55 a good, reliable engine for IMAC and some 3D in a 50cc size plane, or am I better off staying with the more common engines that you can still get parts for?

 

[Mr.Anderson]

I've had one since they came out. Mounted inverted in a Slipstream 90" SBach 342, turning a Xoar 24x8 @ 6500RPM on the ground. . It's my IMAC plane. I hand start it and it's never started backwards. The starting sequence is more tedious with more steps but it always starts on the first or second flip after the priming sequence.

I still struggle to get enough cooling air over it. I have a thermocouple at the top rear of the cylinder head right next to the Pitts muffler can. It routinely spikes over 330F on up lines but settles down to around 315-ish in horizontal flight at 3/4 throttle or so.

I might have only 25 flights of 10 mins each on it though..


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