The firewall is two layers of liteply. As you know, the outer layer hasn't got any holes through it except for the pushrod and the bolts. What is amazing is that the inner layer has lightening holes. Amazing. The 1st picture shows how cleanly the two layer LITEPLY can be punched out. The fact there are lightening holes in LITEPLY and that stuff is being used in a firewall tells you something about the designer. Amazing. LITEPLY is probably the least uniform construction material we have. It's basically one layer of indifferent wood with a veneer on each side. The only real effect the veneers have is to hide the flaws in the inner crap. It's actually magic as fuselage sides and bulkheads with sensible lightening holes placed logically, but it's really not somthing that should be expected to adequately carry an engine, even one sized to the job, and certainly should not be expected to stand up to even the motor mount being tightened securely with 4 bolts. whatever...........

As for Skybolts needing 4strokes to return from the wars with little exhaust residue............... another myth.
It takes 50cents worth of tubing and 2 minutes time to bust that myth. There are no rules that say you can't do something to cure a problem. And when the cure is braindead simple................ hhhmmmmmmmmmm

Yeah, 2strokes put out exhaust residue. No laws say you can't blow it away from the airplane. 2nd picture....... Look down where the muffler pipes come out. 50Cents and 2 minutes. And they might even have a positive aerodynamic effect. [sm=wink_smile.gif] Matter of fact, I'm not sure they don't give the airplane maybe 20-25mph more top end.