I have a GP Extra 300 .40 with a TT46 on it. Any proven engine recommendations? I just started flying it and at this point things do not seem too powerfull. But, I just started flying this and have not leaned the engine at all just running rich.

Mine started life with an OS.70 surpass and now has an
OS.91 surpass on it. Seems just about right to me. ;-)
Jerry

I wouldn't put anything bigger than an OS 70 4-stroker on it. With this engine, tail weight is required. I think that anything bigger would be too heavy.

ys 63[8D] the saito 82 would be good on it to

I saw the same plane fly at our local fun fly. The pilot had the new OS 70 surpass. I was quite impressed. The motor really made the plane scoot. With some very nice vertical for what prop he was using, since it was still breaking in. If he changed with the lower pitch prop. A rocket!!

I have been researching an see OS FX 61 Max as a good enine match. Any exp. with this engine?

Wait until the TT is broken in, then put a Tower Hobbies/GMS/Hobbico tuned muffler ($14) on it, tune it properly & put an APC 12-4 on it. I doubt if you will complain after that.

I looked on Tower for the tuned muffler you mentioned and cannot find it. Sounds silly but could you provide a PN for the TT 46 Pro tuned muffler. I couldn't find one under any of the three brands.

Look under the section with the Tower engines. It is listed there. Part number should be TOWG4724.

Mark Shuman

As to a replacement, how about an Irvine 53.

A OS 46AX or a 50SX would be enough. Anything bigger than a 61fx would be way over kill, but if you go with the 61fx, you might as well get a 91fx because they have the same bolt pattern and the 91 is lighter. Acceleration straight up is always impressive, but this might over stress the airframe. Just don't fly wot.