I am interested in the .46 size. I heard the FXi has more power but looking at them, you cant tell any difference... Is there really a significant difference in the two?

G'day Mate,
I don't think there is any difference, the FXi comes packaged with RTF planes, I believe.
The FX is the older version of the AX, which does have slightly more power, & is possibly slightly quieter, but the FX is still a great motor.
A guy in our club had a ST 51, in his pattern type plane, had all sorts of problems with it, so he changed to a 46FX, & has won the last 2 pattern comps that he entered, & with no engine problems.

The FXi is the RTF trainer version of the FX. It has a low compression head. Therefore is easy to start and adjust but doesn't have as much power as the original FX. The FXi also has needle valve setting restrictors.

The FXi has a lot more power than the LA series engine.

The FXi is easy to spot among FX engines as the head fins are rounded front and rear like on a LA engine. It also has the needle valve restrictors.

Thanks for the replies guys....Do you know if there is any noticeable difference in noise? It seems to me that since the FXi is lower compression, it would be slightly quieter....is that correct?

The FXi is slightly quieter than the original FX

The only real difference in the FX & FXi is the cylinder head.

http://www2.towerhobbies.com/cgi-bin...?&I=LXCK12&P=7

http://www2.towerhobbies.com/cgi-bin...?&I=LXFJY4&P=7

thanks a lot w8ye....lots of good information.