GP Extra 300 .40 Size with .61 FX
 

Does anyone have experience putting a larger engine (OS Max .61 FX) in a .40-.51 Size GP Extra 300. I originally intended on putting the .46 FX in the model but was told by a friend to go ahead with the .61 FX

What will be the biggest hurdle? Weight & balance? Cowl problems?

Thanks
Matt

GP Extra 300 .40 Size with .61 FX
 

Try it and see. I have a 61FX in a 40 size cub, and it does fine. Of course the extra will be a bit lighter than the cub, I think.

RE: GP Extra 300 .40 Size with .61 FX
 

I had the 46 fx in this plane but felt it was underpowered.. (at least @ 5,200 ft. above sea level)

RE: GP Extra 300 .40 Size with .61 FX
 

A pal of mine has one with a 46FX, and I was not impressed. A 61FX, and maybe a Bisson Custom Muffler, would be nice. I don't know how big of a prop you could get on it. I'd want a 13x6, or so, if it were mine. Also, be prepared to move a servo or two to the tail.

Good luck, and let us know how it goes.

RE: GP Extra 300 .40 Size with .61 FX
 

I have this plane with an OS 61 fx. I run a 13 6 prop. Its a great combination. Nice and fast. the virtical is all you'de ever need for IMAC. Mine even hovers, all though the climb out when you go to full throttle is SLOOOOWWWW.

RE: GP Extra 300 .40 Size with .61 FX
 

hey aero dave,

Any idea what rpm you are turning with the 13x6.
I have tried the 13x5 @ 10200 and 12x6 @ 11400
13x5 seems to be a little slow, but good vert.

RE: GP Extra 300 .40 Size with .61 FX
 

I have completed the airframe and did a preliminary balance check with the O.S. 61 fx and hardware mounted. I thought the plane would need a lot of weight in the tail with the servo/receiver setup recommended in the manual. I tried moving the battery aft, and it was not enough weight ot make a significant difference. I decided to move the servos to the after portion of the fuselage. Hopefully I can update the group whether these mods were helpful or not.