Opposed-Piston Engines

[ss55]

Here is a little more detail on what is an opposed piston engine:

https://www.youtube.com/watch?v=NoOB2Kc8Kro

https://en.wikipedia.org/wiki/Opposed-piston_engine

 

[used red MN]

First off a ..point of interest.. article usually is made ..news.. worthy to MSN by the amount of money feeding it, NOT by whether or not it is potentially truthful.
Just using common sense there is no way the design of that engine is anywhere near as low of an emission engine as the common 4 stroke engine. I may be wrong but having the greatest amount of ..fresh.. combustion air is essential to good engine combustion and secondly clean emissions. Look at what is happening in that engine design when the exhaust port opens. The cylinders are far apart, there is a huge cavity that can hold all kinds of burnt gases from the previous combustion event. Compare that to the 4 stroke engine where the exhaust stroke ends with the piston up close to the head with a very small area where hardly any combustion byproducts can remain. Of course comparing the 4 cycle to a 2 cycle, the 2 cycle does alleviate a lot of inefficiencies of the strokes that are power robbers in the 4 cycle. As far as that goes, maybe the inherent design of these engines to ..recirculate exhaust gases.. is more helpful to it having low emissions than I know.
Napier Deltic opposed cylinder engine

 

[used red MN]

The only thing opposed about a Detroit is your ears to the noise!

 

[JMOR]

(quoted from post at 10:42:53 10/05/23) yep, Subaru still uses that term to describe their 4cyl, horizontally opposed, water cooled engine. Odd car front wheel drive design as the engine is ahead of the transaxle.

FLAT PLANE, HORIZONTAL, BOXER as in Subaru, Porsche, ....
[u:0fda7de840]NOT[/u:0fda7de840] an OPPOSED PISTON ENGINE

DUAL CRANKSHAFT OPPOSED PISTON ENGINE

SINGLE CRANKSHAFT OPPOSED PISTON ENGINE

 

[Russ from MN]

I once toured a submarine on display in Mobil harbor that had opposed piston engines, this an interesting article about the engines, still produced in Beloit WI, since 1938!

The Fairbanks-Morse 38 8-1/8 is a diesel engine of the two-stroke, opposed-piston type.[1] It was developed in the 1930s, and is similar in arrangement to a contemporary series of German Bombers aircraft diesels.[2] The engine was used extensively in US diesel electric submarines of the 1940s and 1950s, as backup power on most US nuclear submarines, as well as in other marine applications, stationary power generation, and briefly, locomotives. A slightly modified version, the 38ND 8-1/8, continues in service on Los Angeles-, Seawolf-, and Ohio-class nuclear submarines of the US Navy. The 38 8-1/8 has been in continuous production since its development in 1938, and is currently manufactured by a descendant of Fairbanks-Morse, FMDefense, in Beloit, Wisconsin.

 

[db4600]

Proponents are hailing it as revolutionary

Does it seem that this generation is not recognizing history or is it just being reported that way?

Several examples of near century old OP engines. Ill try to add two more. Look up Kansa City Lightening and Snow Pumping engines.

 

[Janicholson]

Complexity, Friction, weight, reciprocating mass, reparability, are all very negative elements in a (toward each other) opposed engine. The technology of interest to me is more toward hydrogen based spark ignition systems. (diesel designs using hydrogen have had poor performance and reliability for flame travel rate issues and often need dual fuel design to ignite properly with diesel fuel direct injection into a lean hydrogen air mixture. Check the article. Jim
SAE article

 

[4520BW]

 

[Janicholson]

Beautiful design and modular features. The military does not need to meet Emissions requirements, or fuel efficiency. Nice though. Jim

 

[fdt860]

The french company MAP (aris weapons manufacturer) built a tractor and engine right after the war that was a two strokes, with opposed pistons, 2 big rockers, and one crank. The map tractor had only two cylinders (4 pistons), but a 4 cylinders was made for a car that did speed records.
Map engines had a problem with the rocker shafts turning in the bore and preventing lubrication.
The design and factory was sold to simca, but only the tractor tranny was kept, and became the Someca DA50, a very strong workhorse, with a muchmore reliable Fiat engine. A DA50 or someca som 40 is not afraid of any john deere or ih of the same period,as far as reliability is concerned.

There are pictures and a movie of a cutaway engine.

https://mototracteurs.forumactif.com/t64072-recherche-tracteur-map-dr3




Second famous one is the french made CLM engine,probably with a junkers license. This economical diesel engine was offered as a repower for the ferguson te20 in the single cylinder version, and some tractors like Labourier offered a 2 cylinders version from the factory.

Movie of a fordson N with a clm 2 cylinders.

https://youtu.be/0Oud6Pa0Bag?si=aEKF9Y_-QIZ2fKVO

Labourier LD15, one of the few tractors with a CLM engine.

https://youtu.be/WJQql_QC234?si=mY6BTRylhFD2MOIl

The clm were very fuel efficient.

 

[Swede in IOWA]

Lycoming built a six-cylinder vertical, opposed piston engine used is small helicopters. They were very good engines. Swede

 

[cdmn]

As a kid, I read a book about vintage racing in England. They
used a Gobran Brille, (might have been a former fire truck) It
featured an opposed piston engine, which really interested me.
They were the first car to exceed 100 mph.

Interestingly, the Ericsson Engine used in the USS Monitor was opposed piston.
However, it was steam-powered.
Gobran

 

[MarkB_MI]

> Didn't they call some horizontal piston boxer engines?

Supposedly the movement of the pistons is reminiscent of boxer. I never saw the resemblance.

The Porsche Boxster sports car is named for its mid-mounted boxer engine.

 

[Bill(Wis)]

Franklin before Lycoming. I have several thousand hours piloting small helicopters with vertical opposed engines and hundreds of hours piloting small airplanes with opposed engines.

 

[Bill(Wis)]

Many automobiles still are equipped with opposed (boxer) engines. Subaru being the most prominent .

 

[Bill(Wis)]

George. I think we might be talking apples and oranges because you might be talking about an engine in which the pistons are moving toward each other whereas I'm talking about engines in which the pistons move away from each other. At any rate, I'm unable to tell if that's the case because I'm unable to open the links you provide. I get something resembling a butterfly with MSN beside it and a horizontal line moving back and forth underneath. I have no capability of dealing with that.

 

[MarkB_MI]

Lycoming, Subaru, BMW, Porsche, et al. do not make opposed-PISTON engines. They make opposed-CYLINDER engines.

Majorman correctly answered George's question with examples of opposed-piston farm tractors.

Opposed piston engines feature two pistons operating in a single cylinder. They lack cylinder heads and often have two separate crankshafts geared together. Lack of a cylinder head means there's no place for poppet valves to go, so most opposed-piston engines are two-stroke diesels. The main advantage of the opposed-piston design is it eliminates heat loss through the cylnder head, theoretically improving efficiency.

The <a href=https://www.drive.com.au/news/four-cylinders-eight-pistons-and-no-valves-meet-cummins-new-1000hp-tank-engine/>Cummins Advanced Combat Engine</a> referenced by 4520BW is evidence the design is far from dead. It has a place where high power density and efficiency are more important than cost or weight.

 

[uglydukwling]

Rolls-Royce also built an opposed-piston engine for military vehicles. It was a multi-fuel diesel. I believe the designation was k-60. One feature I remember was that the upper and lower crankshafts were a few degrees out of phase. Apparently that improved performance. I don't know whether that was usual for opposed piston engines or unique to this one.

 

[docmirror]

(quoted from post at 08:48:59 10/05/23)

(quoted from post at 10:42:53 10/05/23) yep, Subaru still uses that term to describe their 4cyl, horizontally opposed, water cooled engine. Odd car front wheel drive design as the engine is ahead of the transaxle.

FLAT PLANE, HORIZONTAL, BOXER as in Subaru, Porsche, ....
[u:939da0df69]NOT[/u:939da0df69] an OPPOSED PISTON ENGINE

DUAL CRANKSHAFT OPPOSED PISTON ENGINE

SINGLE CRANKSHAFT OPPOSED PISTON ENGINE

The firsts pic is a cross plane boxer. The middle crank throws are 90deg to the first and third. Flat plane, would have the middle journals in line with the others. I'm not sure how well that would work on a boxer/flat engine.