Wouldnt a company make a ton of cash and save the modeler a lot of money if they produced a gas engines (not glow) in the 40-90 size displacement range? Seems to me a gallon of pre-mix fuel is 6 times cheaper than a gallon of glow fuel. Some company out there could make a ton of money if they did!! I see the smallest on the market is the 1.3 first place engine, scale that in half and you would have a perfect 60 size engine that saves a lot of money. Just a thought and wishfull thinking.

I think it has to do with the extra's that a gas engine needs to run that add weight. Ignition system, spark plugs etc... The gasers I've seen take the same type spark plugs as weed wackers and chain saws.

I really think its more of a power to weight issue...

Why couldnt the manufacturer scale the plug down to size and also the electronics as well? They do it for other engines. I saw a weed whacker at wal-mart the other day with a 18cc engine (approximately 1.08 size) and it looked really small to me compared to the other engines out there.

I think it also has to do with teh properties of gasoline.

Gasoline requires a much hotter spark to ignite it. And once ignited, is quite hot! Much more so, than glow fuel. And wiht this 'extra punch' you need to start making stronger parts, which might require more material / a beefier part, and, well, more of everthing..

And as stated, you need to have an ignition system, which further adds weight...

I think there is also an issue with machining tolerances, with gas they need to be tighter.

Actually, you can do it. And way back when, before glow was invented, gas spark on .60 and smaller engines wasn't just the norm, it was the only way to go.

So, why did everyone go glow on the smaller engines?

Power.

Glow engines produce more power for less weight in a given displacement. I've even heard of some of the giant scale racers converting gas engines to glow operation for more power. And it's no accident that dragsters use fuel that is a lot closer to glow fuel than the stuff you get at the local gas-and-go.

You can take an off the shelf glow engine and covert it to spark and gas if you want. The only mods you'll have to make involve getting a spark, and, maybe, some carb changes. You will run cheaper, but you'll get less power.

If I recall correctly from what I've read, not having done this myself, glow engines burn fuel faster, so the carb openings need to be enlarged when going from gas to glow. But going from glow to gas, all you need to do is lean out the high and low engine needles most of the time. But the mid-range might not track quite as nicely as it should, since it's expecting a glow-type mixture. Probibly depends on the carb though.

The real issue here is power to weight ratio. Oldtimers will tell you of spark ignited engines in that size.

If you create a gasoline powered, 0.60 cubic inch spark ignited engine, it will have about half the power of a 0.60 cubic inch displacement glow engine, and the ignition coil and timing system will weigh about as much as the engine, without the extra battery. Even with a new LiPo battery, that's a power to weight ratio about a fourth as much as the glow engine of comparable displacement. To get similar power, you need that 18cc engine, which is larger and weighs more.

The disparity comes from the way the fuel burns. It combines with and burns with a fixed amount of oxygen. Your 0.60 cubic inch engine will accept (very roughly) about four times as much alcohol as gasoline - which makes for about (again very roughly) twice the power with an alcohol 0.60 as with a gasoline powered 0.60.

So, the reason there aren't a lot of .60 size spark ignited gasoline engines around is that they'd only have the power of a .30 glow engine, and would weigh as much as a 1.20. Roughly.

Or so it seems to me,
Dave Olson

Another alternative to glow fuel is diesel fuel. There are Diesel head kits out there, Davis Diesel markets them. But you have to mix diesel and oil and you get a black ooze out of the exhaust from what I hear. I have always wanted to try it but never had the inclination.

Very informative , thanks for the info and I will keep looking into a cheaper way to fly.....but im sure many others have done the same thing without any results.

Cheaper way to fly? Go electric. For high performace electrics, the up front cost is much higher than glow, but long term it's basically free, no fuel at all. (batteries do wear out eventually, but cost/flight is still much lower than any fueled engine)

Cheap way to fly? Be sure to let us all know, when you find one.

Gasoline power is great, no slime to clean up. Some of the smaller engines cost no more than your high-end glow engines. Cost per-flight becomes mighty low.

This is an expensive sport. Best to focus on what you want, rather than the cost. Want a scale plane? Go for it. Want electric? By all means. Want aerobatic, or sport, or 3D? Have it your way. You can have it good, or fast, or cheap - sometimes you can have two of those categories, but not all three. If you focus on cheap, you're probably looking for a glider (and some of the guys really enjoy them!)

Good luck,
Dave Olson