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| Engines Discuss engines |
Topic Review (Newest First)
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| 01-25-2014 06:16 PM | ||
| jsparky |
Re: Gas Engine conversions withdrawn |
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| 01-25-2014 06:07 PM | ||
| OLD PRAIRIE RED NECK |
Re: Gas Engine conversions Quote:
Port timing. Some - not all weed eater engines used a very limited transfer port timing as a way to limit unloaded engine rpm to avoid over revving. As a governor! This makes it so that the engine just will not turn up adequate rpms with a prop mounted. I haven't heard of this issue with chain saw engine conversions. Mounting. Purpose built model engines have very convenient mounting bosses! Weed eaters and chain saws can take quite a but of hack sawing and ingenuity to get them mounted in a plane. Flywheel. Weed eaters tend to have larger bulkier flywheels that need the cooling fins trimmed off. A weight penalty here! That being said many of these engines have quite successfully flown! |
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| 01-25-2014 05:45 PM | ||
| OLD PRAIRIE RED NECK |
Re: Gas Engine conversions Quote:
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| 01-25-2014 04:59 PM | ||
| jsparky |
Re: Gas Engine conversions I have given this much thought.. and have looked for advise from some others of more knowledge than me.. One being an old mechanic and a model pilot.. another being a mechanical engineer ... both have given the same answer.. by way of a question.. besides the method of ignition you are using.. What is the difference between your 25cc model engine and your 25cc weed eater engine ?? |
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| 01-22-2014 08:38 AM | ||
| kip51035 |
Re: Gas Engine conversions Running a glow engine on 40-1 gas oil mixture will probably wear out the crank end con rod bearing. |
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| 01-21-2014 09:04 PM | ||
| jsparky |
Re: Gas Engine conversions Well I think I finally out did myself with this one.. Did a gas conversion on a nitro engine.. Only differance is that I used a glow plug.. check out the video.. Still have a few bugs to work out like air in the fuel line.. Don't know where it is coming from.. Made sure I have all good fuel lines in the tank.. [YOUTUBE]http://www.youtube.com/watch?v=3vPjm...ature=youtu.be[/YOUTUBE] |
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| 12-29-2013 07:51 PM | ||
| OLD PRAIRIE RED NECK |
Re: Gas Engine conversions Quote:
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| 12-29-2013 09:06 AM | ||
| cf-drg |
Re: Gas Engine conversions Re: using glow fuel in a converted engine.. You have to be careful how much you run through the Walbro carb as the rubber diaphragm and other rubber gaskest don't like the glow stuff.. If you were to run glow you might have to look at a different carb for it.. |
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| 12-29-2013 05:32 AM | ||
| OLD PRAIRIE RED NECK |
Re: Gas Engine conversions Quote:
1) a 10 to 20% increase in power depending on the engine, oil/nitro mix and prop size experimentation. 2) a large power/weight gain by discarding the flywheel and related ignition parts. I'm going to go out on a limb and guess that the test was a bench run only with the same prop that it was swinging on gas and too much oil in the glow fuel hence you missed seeing the advantages. The big disadvantages are that you loose the dependability of ignition and there are more flame outs and dead stick landings and fuel consumption almost doubles. All this was well documented and common knowledge back in the 60's and is why glow fuel became so popular. Everyone was switching their ignition engines to glow! That was a generation ago and has for the most part been forgotten! Funny how thing go in cycles! |
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| 12-28-2013 09:16 AM | ||
| Thunder Chicken |
Re: Gas Engine conversions I converted a homelite 25 and a poulan 46. A friend had a metal lathe and turned me the prop adapters and turned down the flywheels. The 25cc spun a 16" prop, the 46 spun an 18" prop. I did not have a tach or try bigger props at the time. They both ran ok, however I used them on spads. If I had a nice plans worth upwards of a grand, i'd be putting a quality engine on it!! The Zenoah G20 i run is a beauty of an engine, compared to the homelite. However, maybe a bit fancy for a big ole' spad! We also tried running the homelite on a gas/glow mixture with no ignition (just a glow plug) Had moderate success with that although no real advantage in doing so other than the fun of it! |
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