A California project is working to produce a radically different commercial diesel engine that emits much less, burns less fuel, and produces the same or more power as a conventional diesel powerplant in smaller-displacement package.

This on-road demo eventually will see this new engine under the hood of a Peterbilt Model 579. At the heart of the project is a 10L two-stroke opposed piston engine from Achates Power.

A traditional four-stroke engine has a single piston per cylinder being driven up and down as fuel and air come in, are compressed and are ignited, and exhaust gases are then pushed out. Valves, injectors, nozzles and spark ignition typically facilitate that orchestra from the cylinder head above.

An opposed-piston engine is very different—two linked pistons push back and forth in each cylinder—and there's no cylinder head at all.

"Throughout the 20th century, when the utmost fuel, weight and volume efficiencies were required to propel aircraft, ships and vehicles, an unconventional type of compression ignition engine was used: opposed-piston engines," Achates states on its website.

The California Air Resources Board (CARB) provided $9 million to CALSTART, a clean transportation catalyst group that's managing the project. Achates Power will provide the engine and is leading a project team of Aramco Services, BASF, Corning, Dana, Delphi, Eaton, Faurecia, Federal Mogul, Honeywell, Litens and Federal Mogul joined also by the Southwest Research Institute.

This 10L opposed-piston diesel will be roughly equivalent to a 15L four-stroke, according to Mihai Dorobantu, director of technology planning and government affairs at Eaton Vehicle Group. Eaton technology will manage the precise airflow needed for the opposed-piston engine with a TVS air pump, and the company is developing a new TVS pump for the purpose.

Achates was formed in 2004 and has been working on opposed-piston engines for the U.S. military. Achates and Cummins Inc. have been collaborating on a new family of engines for the U.S. Army since 2014 and are slated to build, test and commercialize new products in that vein within about the next three years.

The opposed-piston engine design is scalable and efficient, according to Achates, and could be used to make engines for that effort anywhere from a 4.0L 300 hp. to a 20.0L 1,500 hp. unit.

Some claimed benefits of an opposed-piston engine vs. a conventional design include:

1. Lower fuel consumption. Opposed-piston engines are said to wring more power out of less displacement and fuel burned with their more efficient design.

2. Lower emissions. The CALSTART demo is targeting CARB's lowest Ultra-Low NOx standard while also lowering CO2 emissions "well below today's best trucks," according to Achates, up to 15-20% less carbon emissions than required under current greenhouse gas standards.

3. Simplified engine and components with cylinder head/ valvetrain eliminated. It could translate to less friction, loss and overall cost for this type of internal combustion engine as well as related benefits like less maintenance.

https://www.fleetowner.com/run...4523b567fc0e25a2ba75

Decades ago we had a two-stroke opposed piston diesel engine for submarines. The design provides much more complete scavenging of combustion gasses than conventional designs.

My home town bought some of those engines for its power & light plant.

Edit: Just remembered that it was the Fairbanks Morse engine.

https://en.m.wikipedia.org/wik..._8-1/8_diesel_engine

This message has been edited. Last edited by: Pipe Smoker,

Very interesting and simple in its design.
I sure hope this gets off the ground, it could be revolutionary.

I’d love to see a clean burning, powerful, and affordable diesel. I hope it pans out.

May instead, Peter out.

More Info on the history of the Engine and the Inventor

I want a Deltic diesel in my truck!

This new two stroke is a modern version of an old design.
Jump ahead to 38:30.
https://m.youtube.com/watch?v=...pM&feature=youtu.be#

ETA: If you really want to know about the Deltic, here’s the owner’s manual.
http://pigeonsnest.co.uk/stuff/deltic/

Good video. Watched it from 37:00 to the end. Some of the larger diesels(ship engines) are 50% efficient! Our best car/gas engines are approaching 25%. Diesel trucks are around 30 - 33%. 50% is incredible.

Will it roll coal?

I have a 2 stroke oil burner.

My motorhome has a turbocharged Detroit Diesel 6V92 just getting broken in at 200K miles.

Pipe Smoker,

we probably use a near identical engine for emergency power at nuke plant.

They are a 12 cylinder, opposed cylinder, 2-stoke from around the 70's. They're pretty neat.

quote:

Originally posted by Jeff Yarchin:
I have a 2 stroke oil burner.

My motorhome has a turbocharged Detroit Diesel 6V92 just getting broken in at 200K miles.

Good engine.

I have cut a few knuckles working on them and the 8V92.

The first thing I thought of when reading the title was no way an old 2 stroke Detroit gonna meet modern emissions. I still have my reservations since emissions are getting to the point where diesels no longer make sense.

quote:

Originally posted by Jeff Yarchin:
I have a 2 stroke oil burner.

My motorhome has a turbocharged Detroit Diesel 6V92 just getting broken in at 200K miles.

Drove a few 318's (8v71) in the day. You could oil the road with the amount of oil they slobbered. Run them out of fuel and you might as well call a mechanic. I love their sound, such a smooth purr.

My Dad, before he passed, had a converted GMC 4106 motorhome with a turbocharged 6v92. That bus would really scoot.