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Posted by: bondo Aug 10 2004, 12:50 PM

Has anyone ever attempted this sort of conversion? I would think it would require VERY extreme mods to the case and cylinders.. but you could get soooo much power! (and a hole in the ozone layer that follows you around)

Posted by: phantom914 Aug 10 2004, 12:58 PM

You want to run it on CFC's?

Posted by: J P Stein Aug 10 2004, 01:06 PM

Are you any relation to Mueller?

Posted by: phantom914 Aug 10 2004, 01:08 PM

What about mods to the case and using heads and cylinders from four air-cooled open class dirt bike engines. My 490cc made about 50 HP and 4x ft-lbs. Multiply that by 4 and that would be one hot engine.

Andrew

Posted by: crash914 Aug 10 2004, 01:28 PM

Hmmmm...I did have the thought of installing a motor from an outboard...only problem was the drag from dragging a lake arould with you....

Posted by: phantom914 Aug 10 2004, 01:30 PM

..and the rust

Andrew

Posted by: Jake Raby Aug 10 2004, 01:53 PM

It has been done, more than once. The cylinders were very wild!

With enough time/ money anything is possible!

Posted by: bondo Aug 10 2004, 02:36 PM

Jake: hehe, I figured if anyone knew it'd be you Do you know what the power output/longevity was?

Posted by: rdauenhauer Aug 10 2004, 02:44 PM

Why re-engineer just find the 3 cyl. from a Saab Sonnet

Posted by: lapuwali Aug 10 2004, 03:02 PM

One doesn't necessarily need to redo the cylinders, though it would still be a major job. You could run the cam at crank speed and use a custom fuel injection system. The only time I've seen this done (two-stroke with cams and poppet valves), a supercharger was used as well, to help scavenge the cylinder fast enough on the exhaust stroke. I think it also used direct injection and the blower only pushed air.

Given the valvetrain speeds required, I'd expect you'd either be limited to about 3500rpm, or you'd need OHC heads. At 6000rpm, the valvetrain would "see" the same speeds/loads as it would at 12,000rpm on a four-stroke. I doubt the pushrod valvetrain would hold up to that for long, if at all.

There's been quite of bit of work on making clean two-strokes. An Australian company called Orbital managed to draw a lot of press about 10 years ago, and got GM and Ford interested for awhile. They used direct injection and managed to get a 1.0L three-cylinder to make as much power and torque as a Ford 1.9L four, at less than half the weight, and 2/3rds the size. Emissions w/o a catalyst were equal to the emissions of the 1.9 with a catalyst. Quite impressive. No idea why the idea wasn't pursued. I'd expect longevity concerns were part of it, as well as the politics involved in anything "new".

Posted by: bondo Aug 10 2004, 03:58 PM

Wow, I didn't know 2 stroke technology had gotten that advanced. I suppose these clean 2 strokes have a regular pressure fed oil system instead of the oil in gas setup? Seems that the valvetrain speed issue could be resolved by using 4 valves per cylinder and alternating, so only one valve would be open at a time, reducing valvetrain speed. I could see how a valved 2 stroke would need a turbo or supercharger, if it didn't have the advantage of a pressurized crankcase induction. I should do some experiments with a lawnmower engine.. I could clean up on the Jr. Dragster circuit

Posted by: phantom914 Aug 10 2004, 04:22 PM

Yes, one of the reasons it burned cleaner is that the atomized fuel never entered the crankcase and so never mixed (got contaminated) with the oil. The fuel was injected directly into the combustion chamber with high pressure air (IIRC) to super atomize the fuel.

Andrew