My first RCV is on the way right now for testing. The stuff you are hearing about vibration is from people using the wrong fuel. The vibration is from detonation. Some people just won't follow instructions and try to get an extra 500 RPM out of the engine with hotter fuel. Big no no with this engine. Cooling is not a problem with a radial cowl. I am just making a baffle that will blow right on the front of the engine. This is the only place that really needs cooling on this type engine. If you can get good airflow over the first say 2" of the engine there should be no cooling problems at all. As I can't find a good 3 blade prop of the right size I am going to have to try a Master Airscrew 16X10. This should give about 6000 RPM, which is a bit over the top for the 90SP. I am trying to get Graupner to make a 16X12 and 16X13 3 blade for this engine, the Graupner 3 blade is far and away better than any 3 blade I have used.

I should be doing break in runs in the next week or so. Will let you know on Sal's page how it all works out.
Hans