Opposed Piston Opposed Cylinder motors: Grassroots Motorsports forum: Grassroots Motorsports Magazine

Subscribe get a full year for only $23.95 Sample Free Test Drive—no strings attached

Nov. 16, 2011 11:34 p.m. accordionfolder New Reader

Maybe this is old news to some, but new to me so I'm sharing. With a 1.2L motor in this configuration they can eek out 160hp(!!).

Like the wankle rotary they can be stacked, unlike the rotary motor they have been developed to run the "units" independently.

http://www.ecomotors.com/

http://www.engineeringtv.com/video/Opposed-Piston-Opposed-Cylinder

The power density of these little guys is supposed to be incredible. How much power could they make out of a larger displacement??? They claim 4x the power vs a "comparable" standard motor.

Another benefit, the crankshaft sees very minimal force since they are "perfectly" balanced.....
Nov. 17, 2011 12:12 a.m. mad_machine SuperDork

it's very interesting. I know my father worked on opposed piston diesels when he was in the navy. Those used two cranks.. one above and one below
Nov. 17, 2011 6:50 a.m. alfadriver SuperDork

The idea of opposed pistons has been around for a long time.

For all of the benefits, it would seem as if there are still some significant cost issues. Or some other major reason why they are not seen in passenger cars.

While I can hear the 'entrenched thinking' excuse, bear in mind that there have been a rash of small car start ups all over the world, none of which use this, when they could easily do so and carve out a nice part of the pie.

cost, emissions, economy, packaging- no idea what the issue is, but there apparently is one.
Nov. 17, 2011 7:02 a.m. ThePhranc Reader

New to me. Very cool stuff.
Nov. 17, 2011 8:06 a.m. mike Reader

I have seen the hardware in person (in pieces and assembled), and watched a two-cylinder running on the dyno. I was... underwhelmed. However, the people involved are well-funded and are putting in a massive effort, so the obvious problems I saw may all be solved in time. I won't say more because I saw a lot of proprietary stuff and must keep quiet about the details.
Nov. 17, 2011 8:21 a.m. mad_machine SuperDork

the problem I see.. 2 stroke. No way to get that past emissions for automotive use.
Nov. 17, 2011 8:25 a.m. Alan Cesar Associate Editor

"Oh ja, oh ja. Ve haf demonstraded ze vorking engine, vich has demonstrated ze power." Amusing guy to listen to.

I'm sure those long connecting rods aren't cheap if they're built strong enough to handle compression ignition, and you need two for each outside piston. That's a lot of reciprocating mass; these aren't going to be high-rev screamers. I guess that's why they're best as diesels. And probably best suited to constant-rev applications like generators or aircraft.

The guy admits that oiling those outside points is "a challenge." But imagine the carnage if one breaks! That's something I'd like to see.
Nov. 17, 2011 8:29 a.m. NOHOME HalfDork

I was wondering about the rod angles being so different and if that is going to be an issue.

I also agree that the mass is rather large due to the two rods for the outer cylinder. Maybe the short stroke would compensate?
Nov. 17, 2011 8:38 a.m. erohslc Reader

I don't see anything that couldn't be accomplished by having the pairs of pistons siamesed - think a VW flat 4, with the adjacent cylinders having interconnected combustion chambers.
Nov. 17, 2011 10:05 a.m. iceracer SuperDork

Over the years ther have been many engine ideas that although they worked in principle, they did not show any advantage over the conventional engine. You thinke Subaru engines are wide, look ar the width of that thing. I think durability will be a problem. When we are getting 75 hp per litre in economy engines and over 85 in performance engines ang getting better fuel mileage as well, a new concept will be a tough sell.
Nov. 17, 2011 10:48 a.m. accordionfolder New Reader

They have one designed that (according to popular science) get's 100mpg. PS claimed in their article (once again a claim by itself isn't worth much) that we can expect to see them in a consumer passenger vehicle in 5-6 years. I can't find much online about that so who knows.

The 2-stroke issue is a big one ..... Maybe they're going to target the asia scooter market! If they can get 4x the power vs equivalent displacement ( ?? I wasn't sure if he meant displacement or mass of the engine or...?) then a 49cc opos motor would be downright mean in a "scooter."
Nov. 17, 2011 11:48 a.m. spitfirebill SuperDork

Is Eco Motors the next Solyndra?

Anybody remember the rotary Vee engine?
Nov. 17, 2011 12:37 p.m. familytruckster Reader

That vid is from 2008!

Found a vid of the motor. Note the simplicity of the plumbing. http://www.youtube.com/watch?v=qeKdgybl6SI
Nov. 17, 2011 12:47 p.m. 4cylndrfury SuperDork

familytruckster wrote:

That vid is from 2008!

Found a vid of the motor. Note the simplicity of the plumbing. http://www.youtube.com/watch?v=qeKdgybl6SI

shenanigans...
Nov. 17, 2011 1:54 p.m. mad_machine SuperDork

well.. I see how they are getting around the normal emissions problems of the 2stroke.. I see a turbcharger hung off of the side of it in that vid. Positive Pressure works very well in evacuating spent gases in a 2 stroke
Nov. 17, 2011 2:03 p.m. procainestart Dork

mike wrote:

However, the people involved are well-funded and are putting in a massive effort, so the obvious problems I saw may all be solved in time.

It looks like this is the case. A couple of their press releases indicate that they're getting interest from manufacturers. It'll be interesting to see how the company evolves (or doesn't).
Nov. 17, 2011 2:26 p.m. 81cpcamaro Reader

The engine is a 2-stroke diesel, so no emissions issues like a gas 2-stroke. The crankcase has its own oil, no oil mixed with fuel, just like current 2-stroke diesels. It is being built for tanks and big trucks so it makes sense to use a diesel. Interesting how they are using electric assisted turbos so there isn't the need for a supercharger like 2-stroke diesels usually have. We'll see down the road how it works out.