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I saw this on another forum and thought it was worth sharing.

http://www.autoblog.com/2009/11/30/auto ... #continued
What do you guys think?[/url]

MEP built opposed piston engines 50+ years ago, mostly for submarine use, but many ended up as natural gas compression prime movers.

I've worked on a few over the years, and rebuilt only one. It wasn't as cleanly designed as the engine in the article, with crankshafts around the outside as well as in the center of the engine. Talk about complicated..... I never seen so much rotating craap on an engine. Or used so much plastigauge on one rebuild...

This engine looks much nicer. The soft spot on opposed piston engines is cylinder intake and exhaust.... hard to design and even harder to keep from failure during the running life of the unit. And a real blitch to repair when they crater....

Damn Buzzz is there anything you haven't worked on?
Seems those things would make some pretty high compression with the pistons coming at each other like that. Wonder if the rings last long as a traditional engine.

Just found this vid witht the engineers talking about it.

http://engineeringtv.com/blogs/etv/arch ... ngine.aspx

There is a shitload of stuff I haven't worked on.... but I have spent my fair share of time staring stupidly at some alien-looking hunk of busted machinery, trying to figure it out and where to start fixing it.... keeps things interesting.

After having a bit of a think on this new design, the only thing that jumps out as a possible problem area is the outside piston load distribution is backwards.

In a normal piston-rod-crank arrangement, all the load from combustion power is sent down through the piston to the crank, pushing through the rod and onto the crank. In this engine all that load is pulling on the rod (and most worryingly, the rod cap and bolts) when the outside piston fires. The piston pin will also have to built stronger since it will have to extend past the support of the piston, and give you another rod cap/bolt arrangement to deal with on that rod.... another weak spot.

This design also limits the length of stroke you can have. Specifically the ratio of piston length to stroke length.... but that probably isn't a big problem on bike/automotive sized engines. Once you get into bigger industrial-sized engines, with their much bigger strokes, it might. But industrial engines can be built with much longer pistons to take care of that.

Compression ratio can be 'built in' with piston crown-to crown clearance to get what you want, from a low-comp spark ignited engine to a higher comp diesel compression-fired unit, so that will be engineered the same as any engine. You could build in a variable compression ratio system easily with a variable eccentric on the outside piston pin or something similar. But that's creating a weakness for no real good reason.

Damn you fireguzzi, I looked at this link then went on a 4 hour internet session of researching alternative engine techonalgy. Why did you do this to me? How do you plan on repaying me for my time?

BuzZz wrote: You could build in a variable compression ratio system easily with a variable eccentric on the outside piston pin or something similar. But that's creating a weakness for no real good reason.

You could have performance upgrades with replacement connecting rods though. Longer for higher compression, shorter for lower... depending on what rods you're replacing...

Tennif Shoe wrote:Damn you fireguzzi, I looked at this link then went on a 4 hour internet session of researching alternative engine techonalgy. Why did you do this to me? How do you plan on repaying me for my time?

Hey I pretty much did the same thing to myself. I spent a couple of hours watching youtube videos of opposed piston engines and reading engineering sites.

And if you really want to, you could come have the pleasure of hanging out with my wife and kids for 4 hours while I take your bike out for a ride. That should be enough to pay for all.