4-stroke opposed-piston engine development from Pinnacle Engines?

[hayden55]

These guys signed on with cummins and a couple others for 10 of millions of dollars. Should see some within a couple years. The average efficiency across the entire operating range is phenomenal. Thought they died a couple years ago as I remember reading an opoc article from popular mechanics with them in 2012.

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

[Varn]

I used to be the general manager for a municipal utilities. We had 2 Fairbanks Morse OP motors they were 24 piston 12 cylinder. Had 8 1/8" bore and 12" stroke on each crankshaft. The bottom piston uncovered the intake ports and the top piston had the exhaust ports. It ran off of a big roots supercharger to get it going The exhaust port opened a bit before the intake to start the scavenging process. Once going a turbocharger would come on and pressurize the intake of the Roots letting it freewheel reducing drag.

The pistons were dished making a nearly perfect spherical initial combustion chamber.

The motors were put in in 1960 and by the time I was there in the early 80's they had been run down. Our municipality was in a buying group and the group paid us to keep the group usage lower during peak times. I took our board up to Beloit Wisconsin to tour the fairbanks factory to discuss the rebuild and to tour the factory. The OP motor was made without castings. It was also used in a 9 cyl supercharged only version for nuclear submarines.

[Stubby79]

Would this approach be any different/more efficient than having a conventional in-line engine where two pistons share one combustion chamber?

Then again, what would the difference between that and just one big piston?

Tired brain, this not make sense George...

[Frank Lee]

No heat loss through a cyl head; more of heat energy applied to a "working" component.

[samwichse]

Originally Posted by Shaneajanderson

I heard recently about something like this, I believe it was Mazda that was experimenting with it. The efficiency was supposed to largely come from the fact that it can run on duel fuel. It's supposed to have a tank for diesel, and one for gas. Depending on engine speed, load, and temperature it's supposed to adjust the mix (and it runs on the diesel ignition cycle regardless). Supposedly It can also run on strictly one or the other, but it's optimum would be while running both.

It does not have a second tank, it just uses gasoline compression ignition instead of spark under some circumstances.

Gasoline engine through and through.

[Stubby79]

Originally Posted by Frank Lee

No heat loss through a cyl head; more of heat energy applied to a "working" component.

If that's all it was, they could achieve the same thing by using cylinder head materials that either reject the heat or else get hot and stay hot...also does nothing for heat lost through cylinder walls or in to the piston.

I would think it's a case of capturing more of the expanding gasses force...which you could do with a much longer stroke. Of course it wouldn't rev worth poop, and have to deal with more side forces, but whatever...

[Shaneajanderson]

Originally Posted by samwichse

It does not have a second tank, it just uses gasoline compression ignition instead of spark under some circumstances.

Gasoline engine through and through.

That may not be all bad though, efficiency of the diesel cycle, without the risks of gelling

[Piotrsko]

Part of the diesel efficiency comes from running higher btu content fuel. Gas has lower btu than #2 diesel

[cRiPpLe_rOoStEr]

Originally Posted by hayden55

These guys signed on with cummins and a couple others for 10 of millions of dollars. Should see some within a couple years. The average efficiency across the entire operating range is phenomenal.

That's a whole different animal. Compression-ignition 2-stroke.

Thought they died a couple years ago as I remember reading an opoc article from popular mechanics with them in 2012.

This one is only opposed-piston and with two crankshafts, while the OPOC had only one crankshaft and also featured opposed cylinders.

[hayden55]

Originally Posted by cRiPpLe_rOoStEr

That's a whole different animal. Compression-ignition 2-stroke.




This one is only opposed-piston and with two crankshafts, while the OPOC had only one crankshaft and also featured opposed cylinders.

Oh okay I definitely see your point.