View Full Version : Cummins' "Advanced Combat Engine"
Opposed pistons? Everything old is new again:
"The 14.3-liter power plant is diesel-fueled and uses two-cycle operation rather than the more traditional four-cycle. As such, it must have air forced into the combustion chamber to complete a power stroke. That's where the roots-style "supercharger" comes into play, running on a set of gears and feeding the engine with oxygen. It's similar to old Detroit Diesels, though the layout isn't inline or in a "V"—the cylinders are opposed.
Cummins' ACE has just four cylinders, but eight pistons. Each side has its own crankshaft and the pistons face each other, building enough compression as they meet to complete a power stroke. Also, there's no valvetrain. Instead, as the pistons move between top dead center (TDC) and bottom dead center (BDC) they uncover holes in the combustion chamber that allow air in and out."
https://www.thedrive.com/news/35330/how-cummins-designed-a-14-3l-flat-four-with-eight-pistons-no-valves-and-1000-hp
Apparently being demonstrated this month :
https://www.janes.com/defence-news/news-detail/ausa-2022-cummins-1000-hp-advanced-combat-engine-to-be-demonstrated-in-october
Coal Dragger
10-12-22, 11:16
Congratulations Cummins, you’ve copied a Fairbanks Morse, and Junkers engine design.
FromMyColdDeadHand
10-12-22, 14:16
How heavy for the power?
That's a pretty incredible amount of HP for a diesel engine, I can only imagine what ungodly numbers of torque the thing is putting out.
How heavy for the power?
The version being tested weighs around 3900 pounds.
One More Time
10-12-22, 18:00
Not much heavier than an ISX.
I remember when they put the 903 in trucks for a bit.
Glad that didn't last, only thing I seen them in was White/Freightliner cabover rigs.
It did sound cool though, like the Mack V8.
Bet that new engine sounds pretty bad ass all wound up.
That's a pretty incredible amount of HP for a diesel engine, I can only imagine what ungodly numbers of torque the thing is putting out.
Stoke:Bore ratio is a big factor in that. Just going by the pic it doesn't appear to have a very long stroke but ?. Long stoke helps diesels create big torque.
I don't know much (like zero) about tank drive trains and power requirements. I don't know if big torque numbers are even required. Mebbie one of our Spam Can experts can clue us in.
The version being tested weighs around 3900 pounds.
Jeebus that's heavy. More than 1000lbs more than an N14. Almost double the horsepower though.
One More Time
10-12-22, 18:24
The N14 has three small heads and one cam.
The ISX is about 3,150 lbs.
Cat's weigh a shit ton as well.
Australian speced engines put out a ton of power, way more than other diesels of the same make with V8's and IL6's
But they do the road train thing with trucks.
Hopefully Cummins does a better job supplying spare parts and filters for these than they do their commercial truck engines. I have customers that recently bought Freightliners with Cummins' newest engine in them. They can't run them because Cummins spec'd a new oil filter design, and Cummins doesn't have any of the new filters in stock. Owners are forced to park their trucks or else face voiding their warranty.
Cummins's turbo actuators are also scarce right now.
One More Time
10-12-22, 19:15
It's shitty getting parts for anything.
Our yard is full and we took over the sales lot as there are barely any of those.
Most have been towed out after ordering parts and get towed back in months later.
Haven't seen the forward looking radar for quite a while and the new trucks can't have that disabled now.
There is a lot of stuff that is do not remove till parts are in your hands.
We ordered an engine kit for a 12 liter old Volvo 3 or 4 months ago and I'm just now getting ready to drop it back in.
Took 4 months to get a current Volvo D13 with a compound turbo.
It ran for about 90 seconds and shit itself, had to do the dance around with warranty again and waited for a replacement.
Got the replacement and it had been rolled and was pretty much trashed.
Ordered another one and finally got the damn thing out of my hair.
Poor dude was making payments on a new rig and it sat at the shop for months.
That's a pretty incredible amount of HP for a diesel engine, I can only imagine what ungodly numbers of torque the thing is putting out.
playing around with a calculator and the numbers from Cummins website, it's around 2750.
Diamondback
10-12-22, 20:22
Congratulations Cummins, you’ve copied a Fairbanks Morse, and Junkers engine design.
I was just thinking that this morning when I saw the post on a bus out to Neighborhood Watch... bet it goes over about as well as TrainMasters and C-Liners too.
Coal Dragger
10-12-22, 20:22
Two crankshafts?
Yes. Two cranks that turn gears sharing a common geared output shaft.
No valves, two fuel injectors per cylinder. As the pistons come together they form the combustion chamber. The cylinder wall ports on one end scavenge the exhaust, the other side admits pressurized inlet air.
The opposed piston engine also achieves impressive thermal efficiency.
Coal Dragger
10-12-22, 20:26
I was just thinking that this morning when I saw the post on a bus out to Neighborhood Watch... bet it goes over about as well as TrainMasters and C-Liners too.
The Ruskies used an opposed piston engine in some armored vehicles. The Brits used the Deltic opposed piston diesel in rail service, and the US Navy used opposed piston diesels in US fleet submarines as primary power in WWII, and for shore power to the present day.
Diamondback
10-12-22, 20:32
The Ruskies used an opposed piston engine in some armored vehicles. The Brits used the Deltic opposed piston diesel in rail service, and the US Navy used opposed piston diesels in US fleet submarines as primary power in WWII, and for shore power to the present day.
Yessir, but for some reason the rail industry of the 1950s HATED the FM 38D8-1/8, when... well, personally I think what they should have done was concentrate their FM fleets in one place and headhunt former submariners to maintain 'em. (I've always had an odd fascination with the NYC 4500's, five-axle FM passenger units that were smaller, lighter and 200-400hp more powerful than their EMD and Alco competitors but too late and too "special maintenance"--delivered in '52, the highest-power single diesels on the Water Level Route until the first 3000hp GP40s arrived in 1966.)
Pacific5th
10-12-22, 22:35
I was just thinking that this morning when I saw the post on a bus out to Neighborhood Watch... bet it goes over about as well as TrainMasters and C-Liners too.
FM’s train engines were great engines if maintained. There downfall was they needed more maintenance or more difficult work when they went down. RR’s are famous though for doing the least amount of maintenance as possible. Lately there is not a day that goes bud I don’t hear someone talking to Ft Worth on the radio with power issues.
Hopefully Cummins does a better job supplying spare parts and filters for these than they do their commercial truck engines. I have customers that recently bought Freightliners with Cummins' newest engine in them. They can't run them because Cummins spec'd a new oil filter design, and Cummins doesn't have any of the new filters in stock. Owners are forced to park their trucks or else face voiding their warranty.
Cummins's turbo actuators are also scarce right now.
I wonder what that new filter is? I've got a 2021 Kenworth T880 running an X15 Cummins. Takes a readily available Fleetguard LF14000NN.
Coal Dragger
10-12-22, 22:50
LOL, yup.
All Ft. Worthless mechanical can seem to tell us is to cycle the breakers, and hope the thing wakes up in a better mood. Very helpful Ft. Worthless… thanks I totally didn’t try that at least twice before I even toned you up….
I got into an argument a few years ago with Ft. Worthless Mech and the Orin subdivision DS after blowing up the turbo on an SD70ACE pulling a 2 & 1, 135 car loaded coal train out of Black Thunder mine. Ft. Worth was convinced I needed to cycle all the breakers, because you know that’s all they’ve got to tell you unless there’s a fault code or operator message to give them. Uhhhh no that won’t work there’s hot shrapnel and oil all over the inside of the long hood and it damn near blew a door open, and the guy just asks what the operator message says. Since there wasn’t one, he wanted me to try to restart the engine after cycling the breakers. Oh well not my engine, sounds good let me try…. well Ft. Worth it’s making very expensive sounding noises and still not starting so now what?
Then the DS couldn’t comprehend where we were after being told a bunch of times, and wouldn’t get us a new leader even though I told her repeatedly that we had stalled out. Then got pissed when I told her on the phone that the mechanical responder she’d ordered had a 0% chance of fixing the problem.
Pacific5th
10-13-22, 00:19
LOL, yup.
All Ft. Worthless mechanical can seem to tell us is to cycle the breakers, and hope the thing wakes up in a better mood. Very helpful Ft. Worthless… thanks I totally didn’t try that at least twice before I even toned you up….
I got into an argument a few years ago with Ft. Worthless Mech and the Orin subdivision DS after blowing up the turbo on an SD70ACE pulling a 2 & 1, 135 car loaded coal train out of Black Thunder mine. Ft. Worth was convinced I needed to cycle all the breakers, because you know that’s all they’ve got to tell you unless there’s a fault code or operator message to give them. Uhhhh no that won’t work there’s hot shrapnel and oil all over the inside of the long hood and it damn near blew a door open, and the guy just asks what the operator message says. Since there wasn’t one, he wanted me to try to restart the engine after cycling the breakers. Oh well not my engine, sounds good let me try…. well Ft. Worth it’s making very expensive sounding noises and still not starting so now what?
Then the DS couldn’t comprehend where we were after being told a bunch of times, and wouldn’t get us a new leader even though I told her repeatedly that we had stalled out. Then got pissed when I told her on the phone that the mechanical responder she’d ordered had a 0% chance of fixing the problem.
Lol, yea they pretty much have one play, drop the breakers and hope that fixes it.
Yes. Two cranks that turn gears sharing a common geared output shaft.
No valves, two fuel injectors per cylinder. As the pistons come together they form the combustion chamber. The cylinder wall ports on one end scavenge the exhaust, the other side admits pressurized inlet air.
The opposed piston engine also achieves impressive thermal efficiency.
I see, I was imaging a boxer engine. But it's nothing like that. It's two pistons coming together in the same cylinder with two cranks on either side of the engine. Now that is damn interesting. I can honestly say I haven't heard of that design before.
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