This thread spans from another thread on which the subject came up. I want to know the best engine to fit into an Extra 300 (.60), probably the Goldberg or the Great planes. I have thought about:

O.S .75 AX
O.S .91 FX
Saito 1.00
Zenoah 20cc
O.S 1.20 Surpass w/o pump

Any other ideas are welcome.

Small Block V-8... DUHH!!![sm=bananahead.gif]

Honestly though, How do you want the plane to fly? Pattern, 3D, scale, FASSSST? Slow? What I or anyone else likes may not be what you like. If it where mine... I would want to be able to hover it. Great accelleration and nominal top speed. I would go with a Saito 1.00 with an APC or Zinger 15x6 to 16x4/5ish and even concider the Saito 1.25 with a 17x5 Zinger or 16x5 APC. But when it comes down to it it is personal preference.

The two alternatives I most like are the .75 AX and the Zenoah. The thing that worries me about those two choices are underpowering with the .75 AX and overweight with the Zenoah. I dont really care about hovering. I'm not much into 3D. I like precision aerobatics and have to take into account that I'll be flying at over 7800ft above sea level where engines get a considerable cap on their prompted potential.

I doubt you would be underpowered with the .75AX... It should do what you want with about an 14x6 APC Sport prop.

G'day Mate,
How can you underpower a 60 size plane with a 75.
A 60 will fly it fine, but I ordered a 75AX yesterday for my 60 size Diabolo, it flew great with an OS 61FX, & it will be even better with a 75AX, & a 14x8 prop, if you get a 75AX please use the recomended props size, it is designed to swing a larger prop, than other 75's.

Why is it then that a lot of people recommend a .90? I don't want a sluggish flying plane, but I dont want to do 3D either so I want to know what is a reasonable engine to use.

if you are thinking about the os 60,then you might as well get the 90,if that’s a reasonable price for you. the 90 is the same weight if not lighter with the right muffler. I would assume that is why most people recommend the 90.

Saito 125. Flies my GP Extra with authority.

If you are at such a high elevation maybe you can consider the YS110 ... with its 'supercharge' pressure system it might make things smoother. Its a power house but costly to run as it loves 25% nitro.

I dont know if I'm doing a comparison that I shouldn't do, but the .75 AX is claimed to deliver 2.4hp, the Surpass 1.20 2.1hp, and the Saito 1.00 1.8. I figure this shouldnt mean that the AX will outrun the Surpass or the Saito, so I must be ignoring some fact that has to come into the equation, right?

Plugin,
I'm just finishing a review of the 75 AX for RCU and I can tell you that this engine is a real "stump puller". Putting the 75 in either the GP or Goldberg Extra 300 will give you more than enough power, since you say you don't want to 3D. I think it would be a great combo for either plane.

Ken

Ken, your comments really make me feel confident about choosing the .75. I really like this AX line as I've had remarkable results with the .46. I'll be looking forward to the review! Thanks.