New Cummins two-stroke diesel for the US military

[AmmoManAaron]

This looks interesting.

Cummins developing revolutionary new diesel engine for U.S. Army | Fox News

 

[HoughMade]

I like it. It seems to use proven tech that is well known, but in a unique way. That is a good pathway to quicker development and early reliability over completely new concepts.

 

[IndyDave1776]

I am not impressed. It looks good on paper, but in practice two-cycle engines have problems I am not going to believe can be satisfactorily overcome until after I see it. Further exacerbating the huge claims for this engine is the following:

Apparently the primary engine being benchmarked is the 600 hp Cummins VTA-903T that powers the Bradley Fighting Vehicle and could eventually be replaced by the ACE, which is also destined for the Bradley’s replacement if the project goes well.

Using an obsolete engine as the standard against which the new one is to be judged is somewhere between disingenuous and flagrantly stupid.

 

[T.Lex]

Holy ****.

I *KNOW* the guy who developed that.

That's awesome.

 

[Reverend Dreed]

2 stroke diesel is nothing new. Detroit diesel tried it years ago. They were noisy, leaked oil profusely, and unreliable for the long haul truck market. Thus they were phased out years ago in favor of the 4 stroke engine design.

 

[T.Lex]

2 stroke diesel is nothing new. Detroit diesel tried it years ago. They were noisy, leaked oil profusely, and unreliable for the long haul truck market. Thus they were phased out years ago in favor of the 4 stroke engine design.

The guy I know came up with some REALLY clever modifications based on more modern technology.

 

[IndyDave1776]

2 stroke diesel is nothing new. Detroit diesel tried it years ago. They were noisy, leaked oil profusely, and unreliable for the long haul truck market. Thus they were phased out years ago in favor of the 4 stroke engine design.

The guy I know came up with some REALLY clever modifications based on more modern technology.

I didn't feel it fair to hold up the Screaming Jimmy as proof that it can't be done, but all 2 stroke engines have had problems with air flow, particularly in terms of thoroughly purging exhaust gasses and replacing them with clean air and being less efficient in terms of energy delivered per unit of fuel consumed. Once again, I find it suspect that the Cummins VTA-903 is being held up as the standard for judgment. If they were comparing with a current production electronically controlled 4 stroke engine I would find the comparison much more relevant and honest. This is the equivalent of judging a new car based on how well it stacks up against a Studebaker.

 

[x10]

I am not impressed. It looks good on paper, but in practice two-cycle engines have problems I am not going to believe can be satisfactorily overcome until after I see it. Further exacerbating the huge claims for this engine is the following:



Using an obsolete engine as the standard against which the new one is to be judged is somewhere between disingenuous and flagrantly stupid.

The problem with this statement is the V903 is not an obsolete engine it is one of the biggest success stories of the engine world, it has been updated with electronic controls over the years and is a bullet proof design. I't service life is outstanding and it's down time is one of the lowest in the industry. I've worked with the 903 for 20 years and if all obsolete engines could do what this engine does better than anything on the market today I would take it. But you dont' make money selling the same old thing any more, everyone wants new and better even if it's new and better is only on the box it comes in.

 

[T.Lex]

As I look back over my emails from long ago, I think my buddy actually has a competing project.

This is me not talking about that anymore.

But the OP - that's pretty cool.

 

[PGRChaplain]

2 stroke diesel is nothing new. Detroit diesel tried it years ago. They were noisy, leaked oil profusely, and unreliable for the long haul truck market. Thus they were phased out years ago in favor of the 4 stroke engine design.

the Detroit 71 series engines were used from 1938 to 1995. I drove a lot of trucks with Detroit Power. 2-71 & 4-71 powered a lot of Construction Equipment. They didn't leak anymore than a Cummins if maintained properly. Torque is the biggest difference between 2 vs 4 stroke Disels. A lot of WWII Ships used Detroit power for generating electricity.
https://en.wikipedia.org/wiki/Detroit_Diesel_Series_71

 

[miguel]

Using an obsolete engine as the standard against which the new one is to be judged is somewhere between disingenuous and flagrantly stupid.

Man, I love this quote. I may have a new sig file!

 

[Brad69]

The Army still uses the 903 and the 8V 92 and the big cam

 

[Vigilant]

2 stroke diesel is nothing new. Detroit diesel tried it years ago. They were noisy, leaked oil profusely, and unreliable for the long haul truck market. Thus they were phased out years ago in favor of the 4 stroke engine design.

Hmmm, a Harley Davidson diesel?

 

[CountryBoy19]

2 stroke diesel is nothing new. Detroit diesel tried it years ago.

Tried it? I would say they succeeded at it. From the 30's to the 90's is LONG time for an engine to live with relatively little change.

They were noisy,

Can't deny that one... but oh is that "noise" a sweet noise. It doesn't take a skilled person to pick out the sound of a 2-stroke "Screamin Detroit" from any distance away...

leaked oil profusely,

I will disagree with this. I guess it depends how you define "profusely". Any old engine is going to develop oil leaks and the fact that Detroit's stayed in service for decades means oil leaks were going to become a thing. They don't leak oil anymore than any other engine that stays in service that long.

and unreliable for the long haul truck market. Thus they were phased out years ago in favor of the 4 stroke engine design.

I don't have any experience here. I doubt they are "unreliable" in the sense that they were a market failure. I just think they were replaced by newer, more advanced engines. And that doesn't have any bearing on "reliability", it's only common sense that older designs will be replaced with newer, better technology.

Lastly, none of this discredits the 2-stroke diesel idea. You're trying to include evidence of a single company's implementation of a technology to discredit the entirety of the technology and that is a logical fallacy. I have no doubt that Cummins can take the technology and improve upon it. It's only logical.

FWIW, my dad has Detoit diesels still in use in industrial equipment. What they may lack in reliability (I'm not convinced of your argument, I simply don't have the data to back up a counter-argument) they make up for in ease of rebuild. After many thousands of engine hours dad had to rebuild his 6V53; he did the ENTIRE rebuild, top-to-bottom in the machine. Without cam-shafts to pull, valve-train to deal with, etc, a rebuild is incredibly simple and can be done in a day or less without pulling the engine in most cases. That isn't true for most modern engines. As a matter of fact, with many modern engines rebuilds are so complicated and costly that it's cheaper to just buy a salvage engine and do a swap. Dad recently did a swap on his Peterbilt semi; he put in a salvaged, low-hours fire-truck engine for not much higher cost than a top-to-bottom rebuild of the engine that was in it.

 

[russc2542]

On the one hand, I agree that using the V903 as a standard isn't impressive. But the V903 isn't intended to be a modern pinnacle of emissions on-the-road mass production truck. It's meant to be an unchanged for years, runs on anything, runs forever workhorse that the army can by a million of, leave half wrapped in oily plastic buried in a mountain or underwater, and after an EMP goes off, still have fighting vehicles and spare engines that'll run on whatever fuel you like.

yes, 2 stoke has some drawbacks... emissions being one of them, but if you can live with them, meh.

As for not thoroughly evacuating exhaust gasses... that's a feature now: built in EGR lol.

 

[DRob]

Everything I know about diesels could be inscribed on the head of a pin with a dull shovel but I think the vertically opposed piston concept is much more interesting than 2-stroke vs 4-stroke.

 

[confused89]

I kind of want to see what it will do. Let's put it in a semi.