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ORIGINAL: sam123

Hi everybody, this is my first time posting in this particular forum (I usually stick to the giant scale cars forum).

For a while now I have been thinking about converting a .21 engine out of a 1/8th scale buggy to spark ignition. I have done alot of searching and found lots of good info regarding the conversion of airplane engines, and am amazed at how well they run. I understand that the engines run hotter on gasoline, make a bit less power and require more oil in the fuel than your typical zenoah. None of this worries me, as this is really just an experiment...I just think it will be cool to have such a small engine running on pump gas :D
There are just a few things I am unsure about:

First of all, I see that the engines you guys are converting are much bigger than my engine. Would there be any major problems with converting a .21? Im guessing the higher revs might have something to do with this.

Secondly, why is it that there have been no car/buggy engines converted to spark ignition? If anyone has any info/pictures of converted car engines I would love to see them :)

Finally, these are the parts I am looking at using for my conversion:
cdi : http://www.unitedhobbies.com/UNITEDH...idProduct=6292
hall sensor: http://www.unitedhobbies.com/UNITEDH...idProduct=7868
spark plug: http://www.dlenginesaustralia.com/dl...&productId=127
magnet: http://www.dlenginesaustralia.com/dl...&productId=305

Should this combination of parts be ok? I realise I will have to make an adapter for the spark plug cap ;)

Any help would be greatly appreciated.

Thanks,
Sam.

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ORIGINAL: Nikolas K

Sam,

You are driven by the same motivation that has driven me in converting an ASP .52FS into a gasser. Watch my videos in Youtube if you want. The engine runs extremely well and now I am willing to fly it also, however I have to find the time to install it in the airplane. Anyway, for your engine:
It is indeed a small engine to convert. My idea is that a .50 engine and up is most suitable, as in smaller engines the weight of batteries and ignition system becomes an issue. However, if you want to convert to a gasser, it can be done (imagine, in the '20s, '30s and '40s, before the glow plug invented, there were as small as 0.09 gassers and people were still flying-of course without radio control systems and with large span, slow, airplanes).
As I can see, most of the parts needed are there. However, you need to manufacture a spark plug boot, if you buy this ignition unit. You might also want to consider RCEXL ignition modules for 1/4-32 spark plugs, whose spark plug boot is already there!
Also, the greatest challenge you will face, during conversion according to my opinion, is placing the magnet on the small propellor hub of a .20 engine. It might even bee too big (the magnet) for being properly glued in place...But I do not know your engine exactly, so I cannot imagine your hub.
The timing of the ignition is straightforward, if you have a degree wheel, but another challenge would be placing the sensor holder on the engine. Again, I do not know how you are going to do it, but I used a hose clamp and glued the sensor holder on it. Thus, ignition timing is adjustable, which is a good idea if you make it adjustable as well. My engine needed to lag the ignition some degrees in order to start and work properly without backfires (I haven't reduce the compression).If I had fixed the sensor holder, I would not be able to do so.
If you have more specific answers, do not hesitate to ask.

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ORIGINAL: optech

I've not been following .21 size engine development but aren't they all ABC style construction nowadays? If so, they wont last long on Gasoline fuel. The ABC construction is pretty temperature specific when running. Gas burns hotter so I wouldn't expect the engine to last long. Look for a ringed type engine if you really want to do this.

Mike

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ORIGINAL: sam123


Hmm, the engine I have is of ABC construction, like you mentioned. I guess this could cause some problems [:@]. Do you think I could avoid this by keeping it as cool as possible (using a cooling fan and avoiding full throttle), and use a higher oil content? If the engine does end up dieing, I will definately upgrade to a bigger, ringed engine.

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ORIGINAL: kp96

but can i put a walbro carb on traxxas 3.3 engine. do i need a walbro carb on a traxxas 3.3engine for a glow to gas converstion

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ORIGINAL: captinjohn

The carb may be tricky. But a regular glow carb may work if it will draw fuel & if the needle is not to touchy to adjust. Look up a small RC car that was made in Italy. It was about the same cc & was gas with CD ignition. Capt,n

http://www.classic.rc-junkies.net/?page_id=637

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