Opposed piston engine

[pimento]

I saw this on Autoblog yesterday..

People have been predicting the death of the internal combustion engine for at least 50 years. Thing is, most of the folks making the predictions have themselves died, or been silenced by the fact that ICE is still here and it's better than ever. Still, the technology could be improved. All that sound and all that heat is just inefficient waste. And what about parasitic losses, like power steering pumps and valve train? Well, some OEMs (like Ford) are switching to mileage boosting electronic steering to save some MPG. However, electric valves are a long ways off. Not only would they be infinitely variable, but removing the chains, rods and springs needed to run conventional valves would increase mileage by 20%, at least. And that's just one route.

Another is the EcoMotors International (EM) opoc engine, aka open piston, opposed cylinder. Here's how it works. Instead of an I or a V pattern, EM's opoc is laid out like a two-cylinder boxer engine. However, each cylinder contains two pistons, and they are facing each other. This gives you four rods turning the crankshaft, with no cylinder heads and no valve train (for the record, we're not sure how fuel/air enters and exits). The opoc engine is also a two-stroke, guaranteeing lots of quick torque, but it "runs as a fully balanced 4-cylinder 4-stroke engine."

Shrinky-dinkying the engine has a whole host of other benefits that EM lumps together under the banner, "power density." They include: lower weight and smaller size, fewer materials, less friction, higher MPG, lower missions and less heat rejection. And as the engine is working against itself, there's plenty of built in noise cancellation. Power? Burning diesel, two 100 mm cylinders produce 325 hp and 664 lb-ft of torque @ 2,100 rpm. Nice.

There's an animated view of the engine at its website here. Seems like a pretty great idea, not so much for sports cars but as the generator aboard an electric car a small one could go far.. quite literally. What do you all think, crock or the future?

[Dary]

"two 100 mm cylinders produce 325 hp and 664 lb-ft of torque @ 2,100 rpm"

imagine 5 liters!!

[NSXType-R]

Cooling the engine and keeping it lubricated could be an issue. But hey, if they can dream it up, they can make it work.

In any case, it better sound good.

[uknown]

hope it really comes into production

[johnnynumfiv]

I wonder what kind of compression they are running with these engines. It'd be interesting to see this progress into something used in production cars. I don't see how it'd be hard to keep it cool and lubricated, as long as there is a water jacket and oil passages, all should be good.

[Bob]

Originally Posted by Dary

"two 100 mm cylinders produce 325 hp and 664 lb-ft of torque @ 2,100 rpm"

imagine 5 liters!!

No... solidworks models are not the same as real things. It's a cool idea but I'm really skeptical about that claim.

Also maybe you don't realize that 100mm is nearly a 4" bore and that those two cylinders actually have 4 pistons, and that since the engine is a two stroke (or at least not otto cycle) that 2100 rpm is equivalent to 4200 rpm from an otto cycle engine.

If that was a working engine (correct me if it is) I'd be very impressed- but just doing some cad and calculations is not even close to building a working engine

[clutch-monkey]

isn't this kinda what revetec is doing?

[nota]

Originally Posted by NSXType-R

In any case, it better sound good.

Forgive a slightly OT but the kinda-sorta similar 1953-on Tillings Stevens TS3 aka Commer Knocker engines sound ace

Hillman Car Club of South Australia – Commer TS3 Two Stroke Diesel Engine

YouTube - 1956 Commer C7 MkIII TS3 2-stroke

Even better sonics from this behemoth

YouTube - leyland l60 6 cylinder 12 piston engine (monster)

YouTube - leyland l60 6 cylinder 12 piston engine (monster)

[Matra et Alpine]

Not vyer tech minded the poster in Autoblog ... how air/fule enters is obvious as is exhasut gasses

ANyways, opposed pistons are old idea ( Jumo in Luftwaffe WW2 planes for one ).

What they've got is some neat packaging.
It's a lot of moving mass though, so I suspect best suited to constant speed use.
Would be nice to see it progress.

[Knuto]

Kinda cool design, but I dont see much benifit. I would think an inline 4cyl 2stroke would be simpler and lighter. And if they can make this one produce 664 lb-ft of torque they could probably do the same with an inline design. They also say they eliminate valvetrain... thats pretty normal for 2stroke engines

[Matra et Alpine]

^ You get a LOT better gas flow in and out of the engine and piston speed is lower for the same capcity/compresion ratio ( because TWO pistons move ) So efficiency is "better".

[digitalcraft]

Isn't it basically a boxer engine with the cranks pulling instead of pushing?

[Matra et Alpine]

No. THe boxer engine has a traditional head and valves.
THis has a SECOND piston in each combustion chamber that moves at a different rate and timing, but in opposite direction to the main piston.

[Knuto]

Originally Posted by Matra et Alpine

^ You get a LOT better gas flow in and out of the engine and piston speed is lower for the same capcity/compresion ratio ( because TWO pistons move ) So efficiency is "better".

Ah, OK. But could you explain in more detail?

The way I see it: The piston speed is cut in half compared to an I engine, but you have two pistons per cylinder, so wouldnt you end up with the same friction work??

And could you explain why the gasflow improves? I cant seem to understand this engine

EDIT: I think I see your point on gas flow, but I just wouldn't have thought it made that much difference

[unclematt]

I am very familiar with this engine and design. Advanced Propulsion Technologies has working engines of this type, one a 13hp engine that is so small and light you can easily hold it in one hand. Ecomotors is working on getting production facilities set up in Detroit, so hopefully there will be something new in the engine market to consider soon. There are already opposed diesel engines in aviation circles, and they do quite well.

To answer the question about how the engine is better: no heads, no ignition system, no valvetrain, uniflow cylinder scavenging, double the power density of 4-stroke, multi fuel, and very well balanced.