I need advise on a good powerful engine for the GP Extra 300S .60 size. The current engine is a .91Fx O.S. This is not to bad however, it's a little sluggish regarding vertical. I guess the question is "How much is to much" especially regarding Weight ? I'm all ears, thanks in advance for the help!

hold out for the up- coming ys110.

If you ask me the Saito 100 is the best engine... however the OS91 should pull it unlimited. What prop are you using? How much does the plane weigh?

I had a GMS76 to start with on mine and even at 8lbs 5oz it was almost but not quite unlimited. Of course I didn't realize this until I experimented with different props. With a Master Airscrew and a Zinger wood prop both at 13x6 it was very limited on vertical. A guy told me to try an APC 13x6 and it went from almost no vertical to almost unlimited. It truley showed me that different props, even at the same size, can have a huge effect.

i use a saito 100 on mine and has unlimited verticle at 3 quarter throttle and then at full throttle its almost like its gettin shot out of a rocket going streight up. i am using a 15x6 apc

I have a Saito .91 w/ 14x6 MA prop. I would say a Saito 100 would be absolutely perfect size based on my experience with the .91. For someone that likes to hover the .91 WILL do it, but does not pull out with alot of authority. For me, I am very satisfied with the .91.

I used the Satio 100 and was very pleased with it's aerobatic performance. My fuel of choice is wildcat 15% nitro with 18% synthetic/castor blend (80/20). I use an APC 14x8 prop with a cg location of 4 1/8. I have placed a 1/4 oz stick on weight inside the interior of the cowl.

I hope this helps.

Encluded please find a photo of the plane taken at a nearby sod farm.

blue rabbit