I just bought an Evolution bb.46, and set it up with a 12.25x3.75 prop for my SPA3D. I was playing around with the muffler and noticed that the baffle is removable. If I take it out, will I get more power? I realize it will be louder, but louder doesn't always mean more power. I am running 5% nitro, and can get 11,190 rpms with this setup. It is sufficient, but there's always that allure of just a little more power. I'll pull the baffle and then post the results when the engine cools off.

Guess I answered my own question - 11,600 with no baffle, plus that cool tuned-pipe sound.

Taking the baffle out will help you in gaining RPMs.

I will probably get flamed for this, but I think the 12 1/4 x 3 3/4 prop is too big for .46 sized engines. It seems ok for the .50 and .53 engines out there, but tends too work .46 sized engines a little too much for my taste.

The APC 12x4 is a little better, but my favorite is the APC 11 1/2" x 4.

I would suggest trying all three, and make your own call. I think 11,600 on a .46 sized engine is not high enough. I would shoot for 13,000 minimum, but thats me.

Dave:

I have an APC 12.25x3.75 on an OS 46FX, pulling a Magic.

Excellent set up, no complaints except I can't go flat out in level flight. Not enough pitch for that, but hover/3D there's nothing that works better.

Bill.

Do either of you think that running just 5% nitro is keeping my revs low? I wanted to use up what I had, then buy some 10 or 15%. I like the fact that lower nitro is easier on your engine, but is it really that noticeable? Should I run higher nitro to get more power?

Newbie:

Using the Evolution engine you are not in the "Power" game.

If it runs well on 5% stay with it, until you get an engine that wants 15% or so. The 15% will probably run OK in the Evolution, but the added expense will most likely not give you enough more power to make any difference.

Bill.

So I should have gone with the O.S. FX46? Is there really going to be that much difference in power betweeen the two?

Newbie:

I am not about to say you should have bought the OS. I might have recommended the Magnum XLS 46, but not the OS.

The evolution is a fine engine, from what I've seen, it is designed to be an economical and easy engine to operate, and it does that superbly.

Continue flying it, keep on learning with it, and if you want something hotter get a different engine for the next plane.

Getting the Evolution engine was not a bad choice.

Bill.