This is an interesting engine

[rfuerst911sc]

Yesterday I was doing some random net surfing and came across an article about the Achates diesel engine . It is a 10.6L three cylinder vertical design with six opposed pistons ! A very interesting design to say the least . It looks like the company is in San Diego and the engine is very clean in regards to emissions . I just thought other gear heads might enjoy looking it up and reading about it . Sorry for not posting a link , I am smart phone challenged 😁

[ckelly78z]

This ?

https://www.greencarcongress.com/2020/12/20201218-achates.html

[rfuerst911sc]

Originally Posted by ckelly78z

This ?

https://www.greencarcongress.com/2020/12/20201218-achates.html

Yes that's it , thanks for posting the link .

[kach22i]

I've seen engines like this before on the Internet.

Typically they were in a horizontal boxer configuration, and I don't remember them being Diesel.

No supercharger and or turbocharger?

That exhaust in the video looks a lot like a 1977 Porsche 911's thermal reactor.

The air intake path is wildly long.

https://achatespower.com/opposed-piston-engine-history/

With advancements in technology and innovative engineering methods, Achates Power has created a more fuel-efficient opposed-piston, two-stroke engine that meets today’s stringent emissions standards. By leveraging a broad suite of tools—such as computational fluid dynamics, laser Doppler anemometry, oil sulfur tracing and structural dynamics simulations, to name just a few—we have been able to revive the OPE architecture as a viable alternative for today’s transportation needs.

Yep, I thought it was a 2-stroke.

[peppy]

2 stroke diesel no valve train. I like it!

[peppy]

[beepbeep]

No it is not. It is variation on same theme going on from before WWII. It was first produced by Junkers 1932 (!) as Jumo 205:
https://en.wikipedia.org/wiki/Junkers_Jumo_205

Then patent was bought by Napier & Son, and it had some use in its Deltic engine (which never caught on and was replaced by conventional 4-storkes).
https://en.wikipedia.org/wiki/Napier_Deltic


Fairbanks & Morse developed its own variant in 40's to power locos and U-boats (worse than 4-strokes but kinda compact, so still used where space is at premium):
https://en.wikipedia.org/wiki/Fairbanks_Morse_38_8-1/8_diesel_engine

Russians copied FM engine and made their own to power locos with (but later replaced it with 4-stroke designs which performed better):
https://www.youtube.com/watch?v=ddeAoB_FtSw

Britts hads it's own Leyland L60 that was to power Chieftain (but was so crappy they had to do a crash program to replace it with something that actually worked)
https://en.wikipedia.org/wiki/Leyland_L60


It is like communism....a concept that is "reinvented" every now and then and then found not to work well, over and over. The issues are always the same: low thermal efficiency compared with 4-stoke and difficulty obtaining emissions target ( in Leyland L60 case: bad reliability too). There is always either too much or too little scavenge going on and stroke/bore ratio is geometrically too high (too much cooling). Also, you must have mechanical blower for scavenging purposes at lower revs.

I reckon that company will get some money, fiddle around with it for a while and declare a bankrupcy.

Here in EU, most major truck companies are already talking going fully electric (either batteries or hydrogen) by 2030. And this in light of 4-strokes reaching an apex...chances of trucks being powered by opposed 2-stoke design that failed so many times before are zero. in 15 years, you will not find Volvo, MAN or Scania selling ICE trucks at all.

Basically, an interesting but inferior construction except in certain niche-applications.


P.S.

Almost forgot: Ukranian 5TD and 6TD tank engines (5 and 6 opposed pistons).
They sold a couple to Bangladesh and guess what, engines are shyte!
https://www.defenceaviationpost.com/2020/10/bangladesh-shows-angry-on-faulty-tank-exported-by-china/

[svandamme]

The thing I don't get, is why aren't the trucks doing Hybrid yet?
They are already big and heavy so the weight overhead isn't really a big deal.

They are doing a lot of steady RPM driving where they have more power available then their max speed allows em to do. It's not like passenger cars where a heavy foot kills the gains.. especially not on long hauls..

The Electric drive could then boost them when they need the extra torque

When does a truck polute the most? when it's accelerating, climbing and doing a lot of stopNgo traffic (Tjams, city red lights)

So why don't they go for smaller engines
make up the difference with the hybrid electric drive?

Surely that would be instantly available technology that would reduce their emissions a huge amount. And no worries bout long range autonomy or charging infrastructure , electric network required.. truck charge farms..

It would simply optimize their torque requirements and their emissions.

[beepbeep]

Originally Posted by svandamme

The thing I don't get, is why aren't the trucks doing Hybrid yet?
They are already big and heavy so the weight overhead isn't really a big deal.

They are doing a lot of steady RPM driving where they have more power available then their max speed allows em to do. It's not like passenger cars where a heavy foot kills the gains.. especially not on long hauls..

The Electric drive could then boost them when they need the extra torque

When does a truck polute the most? when it's accelerating, climbing and doing a lot of stopNgo traffic (Tjams, city red lights)

So why don't they go for smaller engines
make up the difference with the hybrid electric drive?

Surely that would be instantly available technology that would reduce their emissions a huge amount. And no worries bout long range autonomy or charging infrastructure , electric network required.. truck charge farms..

It would simply optimize their torque requirements and their emissions.

We have had hybrid city buses for two years. Stop and go is basically only thing buses do, so there is lot gain to recuperate braking into battery.

Trucks on the other hand do mostly steady speed (at least in Sweden, Holland is much smaller) so it is just not worth hauling batteries/inverters and motors if you gonna burn diesel anyway.

Latest development for trucks is going full electric and/or hydrogen with some pantographs available at certain highways. Anyway, I hope we can ween ourself of Arab/Russian crude ASAP.

[Nostril Cheese]

Wow, i didnt realize that Scania is part of VW now. Is it still pretty independent or is it incorporating VW's electric tech?

[unclebilly]

That website was from 2011... about all they could do to make this even more needlessly complicated is to add rotary valves of some kind.

I have actually seen a Fairbanks Morse version of these. There was a wrecked boat washed up on the beach in Margarette Bay in Smiths Inlet back in 1992 when I was commercial fishing there. I remember it specifically as an opposed Fairbanks Morse. I’d never heard of this type of engine before.

[svandamme]

Originally Posted by beepbeep

Trucks on the other hand do mostly steady speed (at least in Sweden, Holland is much smaller) so it is just not worth hauling batteries/inverters and motors if you gonna burn diesel anyway.

Well sure but who says it has to be diesel.
and even with Diesel it allows you to run the engine in it's most efficient way + Add torque when you need it. without a big plume of smoke
Most trucks don't need tractive effort for most of the time they are cruising...Their engines run low rpm, low load for most of their life..And that's not the time when they are polluting.

[petrolhead611]

The Rootes Group in the UK in the 1950s and 1960s made 2 stroke horizontally opposed 3 cylinder 2 stroke diesel engines with chain driven Roots blower. 200 cu in with 270 lbs/ft of torque at 1200 rpm. Totally flat engine that had the cab mounted above it so the cab front was the front of the truck. Engine access was excellent via doors below the cab. Engine only had to come out for work on the single crankshaft. Very noisy engine under load so no good for use on coaches. Some were built as marine engines.

[beepbeep]

Originally Posted by Nostril Cheese

Wow, i didnt realize that Scania is part of VW now. Is it still pretty independent or is it incorporating VW's electric tech?

To my knowledge, VW does not have its own truck electric tech. Scania was (still is?) regarded as a king of trucks, so I reckon they are developing their own and VW is just footing the bill.

[beepbeep]

Originally Posted by svandamme

Well sure but who says it has to be diesel.
and even with Diesel it allows you to run the engine in it's most efficient way + Add torque when you need it. without a big plume of smoke
Most trucks don't need tractive effort for most of the time they are cruising...Their engines run low rpm, low load for most of their life..And that's not the time when they are polluting.

It does not work that way. A typical truck diesel will be most efficient *at part load*, not at full load. So downsizing the engine to go full throttle at steady speed and then filling in with electricity will make it less efficient (on the top of all electric gubbins that must be hauled around). Also, you would have reliability issues.

[beepbeep]

Originally Posted by unclebilly

That website was from 2011... about all they could do to make this even more needlessly complicated is to add rotary valves of some kind.

I have actually seen a Fairbanks Morse version of these. There was a wrecked boat washed up on the beach in Margarette Bay in Smiths Inlet back in 1992 when I was commercial fishing there. I remember it specifically as an opposed Fairbanks Morse. I’d never heard of this type of engine before.

Yupp. US gave copple of boats to Russkies who then copied it and used it for decades. Design has been around forever, periodically dusted up and served as "breakthrough". I never heard of any successful application save from (perhaps) FM design to be used in U-boats where packaging constraints would make other design non-applicable.

Scavenging will always be an issue in two-stroke. You either overscavenge (which gives power) our under-scavenge (which will bring emissions but also power down )

These locos are powered by Russian FM copies: