David,

I think that the cowl is not wide enough for the larger of the two radials (even though it's likely tall and deep enough). I already explored the RCS 150 route, and even that motor is a little too large. According to my measurements, the cowl is about 1/2" too narrow for the RCS 150. Regarding power, I have no doubt that the 150 would fly the Avenger, but it certainly would not be a rocketship.... but then again, this is an Avenger we're talking about.

I hope someone out there goes the radial gasser route... I would love to hear that avenger on fly-by.

Well, the sun us coming up so it's officially OK to start the power tools in the in garage (i.e. get back to work on my Kellogg Avenger).

Noah