JettPilot,

That has been the question about how Evolution has introduced their engines. The .40 (Alpha engine) and .46 share the same cylinders, crankcases, and carbs. You can make the 40 almost into a 46 by using the 46 liner and piston. That gives you a 45, but not the same .45 Trainer Power System engine at all. The crankpin on the 46 is slightly different to give it more stroke. If you put in a 46 crankshaft, you would then have a .46NT. The .40 Alpha is better balanced than the .46NT.

The .45 is a different engine and I don't think it shares any of the same parts. I haven't checked the carbs though.