I saw this today and though you guys might be interested. Cummins is developing an opposed piston two stroke for tanks. One of the articles said they are working on smaller versions as well that might find their way into our buses at some point.
https://www.thedrive.com/news/35330/how-cummins-designed-a-14-3l-flat-four-with-eight-pistons-no-valves-and-1000-hp
For those of you who thought a bull gear was a bad move.
LOL anytime Cummins builds something other than a inline it has problems.what now a tank to use the engine
The new engine is replacing the 903. Not sure what else to say.
That's the same concept as the WWII era Fairbanks-Morse opposed piston engines. They used them on subs and destroyer escorts as prime movers, and they also used them to drive generators. Used a piston pump instead of a Roots blower. All the ones I saw were vertical.
The Crown Coach Junkies folk got all excited at the thought of retrofitting those opposed-piston engines into their mid-engine Crowns and Gilligs with enough power to make them the hotrods of the bus world. Dream on!
Opposed-piston engines aren't new at all, even in road vehicles. The veritable Commer TS3 was one such engine that sounded like a very angry 6V71, except louder. It had three cylinders, six pistons, but only one crankshaft (work that one out!). And of course there was the legendary Napier Deltic, with 18 cylinders, 36 pistons, not a single valve (obviously), and three crankshafts, one of which rotated the opposite direction that the other two. Think of it as the railway and marine equivalent of the 1.5 liter BRM V16 - huge complexity, massive performance when it worked, but maybe not quite the world's best reliability . . . (I've spent many happy hours hanging out of the windows of passenger trains hauled by Deltic locomotives - the sound of 72 pistons hauling 400 tons at 100 MPH is never forgotten.)
In the meanwhile, a 6L71 or a 6V92 is a pretty darn good substitute for an opposed-piston engine, especially if it's unmuffled.
John
CUMMINS has so many engines of proven design I.E. inline 6 and 4's. So naturally, they want to try something different along with problems. Aside from that, it probably sounds neat.
Quote from: CrabbyMilton on August 24, 2020, 03:59:44 AM
CUMMINS has so many engines of proven design I.E. inline 6 and 4's. So naturally, they want to try something different along with problems. Aside from that, it probably sounds neat.
Some of Cummins popular small engines like the 5.9 and the four banger were not Cummins designs, JI Case designed those and had a joint venture with Cummins to build their engines Case did the casting for those back in the 70's in OK at their foundry,even today my 580 M backhoe has the Case/Cummins label,I think the little V engine would have been alright if Cummins would have used gears instead of 15 ft of timing chains
That's true but as far as users go, if the name is on it that's all that matters.
That ISV was mostly designed for the NISSAN TITAN as almost a proprietary engine. But CUMMINS offered it for about 15 minutes to a very few bus and motorhome builders. BLUEBIRD offered it in the VISION for a short time so It's unknown how many of them actually had that engine. NISSAN dropped it so that pretty much ended that long built up engine.
Cummins is in business with Achates Diesel engine company who developed the current engine. There is also a 3 cylinder version that will be available for trucks putting out around 475hp and 1750lb/ft torque. Can hardly wait. Good Luck, TomC
I have worked on a few FairBanks Morse engines with the opposing pistons way,way back when the moon was the size of a golf ball,? wasn't the Mazda rotary a opposing piston gasoline engine
No, no pistons, a rotor. Here is a video:
https://www.youtube.com/watch?v=6BCgl2uumlI (https://www.youtube.com/watch?v=6BCgl2uumlI)
It was a rotary with three firing chambers.>>>Dan
I think it was Subaru thinking back that was working on a opposing piston engine
I was always fond of the opposing piston VW 4 banger. Love the way the case splits in half!
Yeah, we worked on those Mazda rotaries. When they were still using points and dual distributors setting points and timing was a real bitch. The early engines drank oil. Mazda started replacing the engines. The newer RX7's didn't burn any. Interesting power curve. Torque didn't drop off, just kept building. No valves. You could rev the rx2's to 10,000 rpm and it wouldn't hurt them. No valves, just ports.
I am not sure it will make it to the "street".
If I remember my dark dark Environmental Engineer days, the military tactical engines were somewhat exempt from all current "street" engine requirements if strictly tactical off-road, i.e. TANK!! I think that is why they can and still do run at least some two strokes in TANKS.
I did love "my" military multifuel diesel truck engines, where I could "dispose of" old gasoline without having to pay hundreds of dollars to dispose of gasoline as hazardous waste(yes-toluene is hazardous and in gasoline). I had help shielding the last one from transfer to disposal for a couple of years, but eventually the accountants found it and made my unit turn it in!
I remember rotary engines having oil injection to oil the side seals and main seal on the rotary.
Most experience came from Suzika and Hercules engines.
one of the reasons for bad emissions.
been a few years.
uncle ned