What is the biggest engine that the lt40 kadet can handle?

There was a guy at my club that had one with an OS60 2 stroke and a tuned pipe. Seemed to handle it OK, though if you are training with it I would recommend a good .46

A fellow club member has an OS 70 four stroke in his and it flys at about 1/3rd throttle.
Dennis-

I think that thing could "handle" anything smaller than a Chevy Small Block.

Actually, I've seen one of those with a Chevy Small block on the front too. Flew great!

Honestly, you could probibly mount a .90 two-stroke with out too much trouble. You might be able to get a 1.20 in there with a little work.

Of course, you wouldn't want to do this for training, and you'd be putting serious strains on the structure. It would be really easy to rip the stab off the plane or fold the wings.

There are a couple of guys in my club with .90's mounted in .40 size mustang ARFs. They are FAST, but these are really good pilots and you don't see them doing much more than high speed passes, some rolls, and some very very big, open loops. You could do the same with an LT-40, I suppose.

I flew a new LT-40 this weekend for a new student. He had an OS .52 4-stroke in there, and I think it was just about perfect for that airframe's intended uses.

If you're just learning to fly, go with a good .46, or if you must have a 4-stroke, a .50 class will work very well.