Is this engine comparable in top end H.P. to the K&B 4011/8011 series, or is it primarily a sport/stunt engine?

Les

I can't answer the H.P. question but all the G21/40's I've seen were lapped piston engines and not rings.

Hi Bill

I'm always curious about the different engines that qualify for use in TQR. Our club used a lot of G21/35's for fast combat in the 70's, but I've never seen anyone use a G21/40 for anything locally. I don't know if it was because they are not as powerful as the K&B's, or if it was an availability issue. I've used the O.S. 40H. My example wasn't anywhere near as fast as my K&B's, so I set it aside. I was thinking of obtaining an G21/40 for testing, but the collectors crowd has the prices on these jacked way up, and they're kind of scarce too. Was just a thought...

regards, Les

21 / 40 is small bore 21/46. theres ' variations ' Liner O.D. early and late like silencer lugs. Bolt pattern to heads differant to 46 .

Pistons cuttaway fore and aft under, you can see with piston at top , thru ex port. This screws em a little with silencer-ex. is fed back a bit.

Their good for a lotta things, Will swing a 12 x 6 on 4 mm intake on straight no nitro fuel,on the 9 mm intake , c/case pressure and a 11 x 4
its good for doing manouvres upwind in a stunt ship.

Same set up on 20 % nitro its " ive never seen fuel go into an engine so fast " from a 3 decades comp flyer !

Abouta 4 - 5 mm intake for stunt , 11 x 5 prop or trimmed 12 x 5 , and 10 % nitros something like it , stdish muffler. youll get a OS 35 silencer on the non muffler lug one , or if someones shaved the lugs. works good.

9 x 7 for combat, 8 x 8 or 8 x 9 for wottle she do , I guess.

If the old bearings are a bit noisy under punishment , its probl nitro corrosion , and itd pay to fit new QUALITY ones,
after tearing it down and seeing if the rests up to it .

or send it to ME !