Help me get it straight, for a .60 size plane the max 2 stroke would be______, four stroke would be________? I'm never gonna buy another engine in the lower to mid range for a given aircraft size. In fact, lay out the engine size for each plane size please. (.40 and up)

There are variations in structure within the ".60 size" class that make it impractical to say for sure. A kit can be labeled .40 to .60... and people will call it .0 size. it could also be labeled for JUST for a .61 (that would be a larger mnodel than the one labeled .40 to .60...) and REALLY be a .60 class model.

Generally its OK to exceed the listed engine size by one upgrade. (if it saays up to .61... .72 is not too far out of line)

When replaceing a 2-stroke with a 4- stroke, a .52 4-stroke is about the same power as a .46 2-stroke. .72 replaces .61, .91 replaces .72. 1.2 replaces .91. (it'd be closer to use 1.05 to replace the .91... but find one...)

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BTW... sticking too large of an engine on trying to gain performance... you don't always get what you are after. Larger engines generally weigh more. Low speed performance can suffer severely. And then... putting a .91 4-stroke on a Four-Star 40 (as i have seen suggested once) its not the weight that wll be a problem... you can litterally pull the airplane apart with the excess power.

I know that my thinking can get a bit screwed up at times. I guess what I'm trying to do is pick an engine that I can use on more than one size aircraft. I look at the Funtana which is called a 40 size. They fly it with anything from a .46FX to a .91 four stroke. And I even larger I think. That plane is extremely light, I've felt the fuse in a LHS. I've got some cash that's burning a hole in my pocket and can't make up my mind which engine to get. I want to get something that I can replace the 46fx on my spad deb, and maybe put on a 60 size down the road. Or, maybe the H9 Funtana, it's such a pretty little thing.lol I'm leaning toward the FA 80 Saito, or going cheap and getting the Magnum 80 or 91. Oops, gotta go, work calling. will get back to this later

Funtana's will hover with a saito .72 a 91 is not needed.

As a general rule with me at least, if a kit calls for a .60 2 stroke, I always use a .75 2 stroke.

most engine manufacturers have punched out versions of thier basic case sizes irvine 40/46/53 etc. all would fit on a forty size plane. same with the sixty size supertiger 61/75/90.

While the SPAD site says the Deb is a .40 size trainer... its as big as a lot of the .60 size and just as heavy as the Thubder Tiger 60 ssize ARF trainer. A .40 will fly it ( a .40 will fly any of the .60 size trainers...) But it really needs a bit more (.53 Irvine is what I think is ideal)

The SPAD Deb can handle a .72 2-stroke if you beef up the engine mount a bit. Use the longest, lowest pitch prop you can and you won't overspeed the airplane.

The .72 4-stroke will work on anything that says it shold have a .60 on it.

Once you go 4-strke... 2-strokes just aren't worth messing with any more. (almost...)