What is the lightest, most powerful 2-stroke .46 glow engine I can buy?
If you are using an OS 46 FX pipe it or at least get the Tower muffler. It will out run the TT 46 (but not by much). For the ultimate in lightweight go for the Webra speed 50 at 320 grams nothing comes close to it in light weight and it will turn a 10 x 7 prop with the Irvine. The Irvine however will out torque the Webra but you will pay a penalty in weight.
RCM's Clarence Lee review of the Irvine:
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The Irvine 53 is the only 2-stroke engine in this displacement size we have reviewed. The closest to this displacement size would be the Fox 50, Enya 50CX, and Webra Speed 50, with the Webra Speed 50 being top dog. The Webra would turn the 10 x 6 300-400 rpm faster than the Irvine. With the normally used prop sizes, i.e., the 11 x 6 through 12 x 6, both engines turned almost identical rpm. When loaded down with the 13 x 6, the Irvine turned 500-600 rpm faster than the Webra, making it the new "King Of The Hill" when it comes to big prop turning ability in this engine size range. Naturally, the Irvine does have a small displacement advantage, which, incidentally, is actually .5203 cu. in., not quite .53.