How long will our glow engines last?? I was talking with a flying buddy the other day and I made the comment that these new CNC machined engines will last darn near forever if run slightly rich and not crashed. I guessed that “darn near forever” would be about 100 gallons of fuel. Of course I am just guessing! I have used many different engines and burned many, many gallons of glow fuel over the years. But I have not kept track of how many gallons went through any particular engine. And yes I have worn out a few engines for whatever reason.

Does anyone have any idea of how many gallons of glow fuel can be burned in a, say, 40 to 90 size glow engine before it is worn out? We must leave out lean runs and crash damage. [sm=50_50.gif]

OldBob

Does this allow for ring and bearing replacements?

David

I'd say your 100 gallons would be in the ballpark for a 45ish sized engine because they should last for at least several hundred hours whether it's ringed, ABx or whatever. A thousand hours isn't unheard of and under the right conditions an engine has been run to 2000 hours with no appreciable wear (the famous Fox 35 test ).

I don't think that CNC machines can change the lifetime of an engine, and there is sometimes an inflated trust in what computers can do. Don't write off what was done in the past, I think they had a very good feel for what they were doing while lately we only get stuff machined in the far east under primitive conditions...

Dave, yes ring and bearing replacement are allowed. In my experience bearing are the first to go bad and they are easy to replace.

Downunder. I was not aware of the “famous Fox 35 test” I will mention it with authority from now on.

Guys thanks for the feedback

OldBob

I have an ST G60 Bluehead that I finally managed to pry out of a friend's hands. I was there when he bought the engine new and I witnessed him flying it on his pattern ships for a decade or more. Believe me, this guy flew a lot. The engine shows signs of external wear, but the interior/fit of the engine is excellent. This one still turns heads when fired up with either a Mac's open front muffler or a tuned pipe. It spent most of its life swinging an 11x6 prop with a tuned pipe. Today, I can mount it up, fuel it and off she goes in a couple of flips, or less. Like I say, it is rough looking (needs an antifreeze bath), but it is still a solid contender for pulling a classic pattern model. Jim must have replaced the bearings at several points in time, but I don't think he ever replaced the ring in this ABC/ring engine.


Ed Cregger

Anybody have a reference for the "famous Fox 35 test"? I think it's as good story and would like to pass it on to friends.

I'll keep an eye out for it while I browse old magazines (another hobby).

I did come across an old photo of a Fox employee simultaneously test running an entire row of .60's or .74's indoors, open exhaust, with no ear protection.

David

The Fox 35 test is quite well known but the only first hand reference to it that I know of is over at SSW buried deep in the past but I'll see if I can find it. Basically, Duke Fox set up one of his engines on a test stand and hooked it up to a monster fuel tank. The engine would be started every morning and stopped when the factory closed each night. This continued for 2000 hours when he stripped the engine to check it out. The engine was in such good condition he figured it wasn't worth the effort of going any longer. Of course, he was using his own fuel that's the standard brew for a Fox 35 with 29% castor but the corollary to this story is that he also took a Fox 35 to see how long it'd last on normal RC fuel. It was ruined within minutes.

Thanks, Brian, that's a good start.

My friends large OS 4-stroke uses about an ounce of fuel per minute. In 2000 hours that would be 2000*60 ounces. One gallon is 128 oz so that would be 2000*60/128 gal.

If you were to do it today at $20.00 (US) /gal that would be $2000*60/128*20.
$18,750. Anybody want to try it? :-)

Plus OS was probably the first CNC engines, and it did not improve their life. Fox and Enya would outlast an OS, it was the harder metal, not the CNC machining. Now I think all engines are CNC, it makes for faster production, but especially for small lots such as model engines it does little to nothing for accuracy. In fact a hand machined engine made with care is probably better.

All I can tell you is that the engines always outlast my airplanes and radios. I still have all my engines and have thrown away about 25 or so planes



Max

All of the used engines that I have inspected had damage from dirt, some more than others. Corrosion and dried oil kills bearings that in turn ruin the rest of an otherwise good engine. The reason that OS engines seem to wear out faster is also the reason that they run so well out of the box. They have more piston/liner clearence than many other brands.