Hi guys, I'm looking for some sort of guidelines to go by for swapping between gas and nitro sizes. Such as .60 comparing to a 20cc gasser. I'm sure that's not right but that's kind of what I'm looking for. Is there a thread or website that already has this laid out maybe? I'm looking in the 20, 26, 38cc area. Thanks for any help.

A 60 glow motor has a 10cc diplacement, you can compare like for like i.e. a 50cc petrol is the equivilant of a 300 glow motor, does anyone make a 300 glow motor? besides the fact that petrol burns hotter they are both just two strokes in the end.

This is a rough comparison as some petrol motors are more powerfull than others.

Mike

It all really comes down to the physical size comparison (will it fit), weight comparison (watch wing loading), and power comparison (ability to turn a given prop at a given rpm). Aside from that, different makes and models of two or four stroke glow, or gas engines all of the same displacement can vary greatly in power. You can compare cubic inches, or cubic centimeters for a displacement comparison, but the power/weight/size comparison will be quite different, and in the end, what you are really concerned about.

Chad

With the gas/petrol two-stroke producing substantially less power than the glow fueled two-stroke of the same displacement.


Ed Cregger

Thanks Arobatx for your answer, that gives me a better perspective.

To give you guys a better idea of where I'm going on this, I'm looking at a 1/4 scale Wing Derringer twin with an 87" wingspan, 1137 sq. in. wing area, and a projected weight of 24-27 pounds. They recommend .60-.75 2C glow engines.

I'm basically trying to avoid using glow and just use gas. Would I possibly be okay with something like the Zenoah G-20? Or does anyone have any other recommendations?

Thanks

Is your Wing Derringer from the RCM plan? I really like the look of that plane. You could probably use the Zenoah G-20e engines, but it is a lot more engine than needed.
I would choose to use two Saito four strokes, say FA-91 to FA-125. Not only do they sound much better, you will also save about 1-1.5 lbs of weight (all things included) by using the lighter glow engines.

If still available, you could also give the BME/G90 a run?!?! A .90 converted to petrol... Nothing will ever replace the sound of a good four stroke though, especially in multi engine warbirds...

I'm not sure who made the plans yet, they're being sent to me and should be here in about a week. Should I be hoping for RCM plans?

I think I should be okay with the weight of the engines, I like the idea of the simplicity of the gas engine. And I think multiples of any engine will sound good. And a little more power will be a good thing as long as the prop will be fitting. Isn't there a saying somewhere that you can never have too much power?

I for one have NEVER heard that saying [X(] ...for example my modified G62 in a Great Planes Ultimate 1.60

I am putting a 18cc gas engine on a .60 ugly stick is that too much motor?