Here's a crazy idea from an ignorant newbie:

Has anyone thought of coupling two conversion engines together to make a twin? It's kinda unusual for gas engines to have shafts protruding from both ends of the crankcase. And since some are precision threaded or tapered, it would seem that they might be able to be linked up by joining the cases and crankshafts with standard precision machinist techniques, carefully done to avoid vibration. A standard mechanical flexible connection could also be utilized. Presumably both would retain their own ignition systems and mags, etc. Perhaps they could be joined 180 degrees out of phase.

Am I nuts or just naive? But this is half the fun, pushing the envelope.

Just thinking of that monsterous 1/2 scale chainsaw powered Mustang with the micro video camera in the cockpit mounted on a servo for 360 degree views of low-level strafing runs...

Not crazy, been done before. Now crazy is a triple, and its been done TOO.

The best example of this is/was made by Russ Stoltz at Challenge Tool, called a Husky Challenger...Fastest examples flown by Dennis Crooks in a P38 at the old Madera races..Two 8.8 twins, methanol fuel, C&H ignition, 2 Rimfire 1/4-32 spark plugs in each cylinder..Got kinda pricey when changing spark plugs between heats...The also made an 11.6 twin and a triple using 4.4 cylinders...the engines are museum quality, and the triple makes a sound like NO other....Another inline twin is made in Canada from 3.2 Sachs engines..Called a Merlin, very pricey....