Have we talked about the Achates Power 2.7L?

While doing some digging on something else, I stumbled across this company called Achates Power who is pushing their vertically-opposed, 3-cylinder, 6-piston, turbocharged 2-stroke gasoline engine as the next big thing in "green" gasoline engines. 

Apparently they have crate motors running around in F-150s, with possibility for production, and they got a good-sized military contract as well. I did see that they have one of the kings of vertically-opposed piston engines, Fairbanks-Morse, signed on as part of the program. They were building 2-stroke diesel OP engines back in the '30s for the Navy and made a stab at railroad engines in the 1940s, which largely failed due to them being just a little too different from the competition.

270hp/480lb-ft sounds pretty stout, especially for a gasoline engine. That sounds more like diesel numbers. I get that the 2-stroke part reduces the amount of parts (no cams, valves, rocker arms, valve springs, etc.) but I thought that 2-strokes were inherently dirty engines, so how are they making them clean enough to be considered a green engine? Maybe something to do with it being compression ignition, or some sort of exhaust aftertreatment like a diesel? I'm curious to see if it takes hold in the automotive industry? I'm also curious to see what they sound like, gotta be pretty interesting exhaust not.

Color me curious 

Now that we live in a time of truck and SUVs, the height of a vertically-opposed engine isn't quite as big a problem. Plenty of room to cram it in there. I'm curious who will be the first to jam one in a Miata.

I wached a few youtube videos about it when they publicized the f150 aspect of it. I think it's interesting!

A green two stroke gas engine?

Maybe with diesel, or maybe with some form of direct injection for gas...

Mr_Asa said:

A green two stroke gas engine?

Maybe with diesel, or maybe with some form of direct injection for gas...

It is direct-injected. Also compression-ignition, like a diesel.

In reply to NickD :

Interesting. 

Wow, it sounds exactly like an old Screamin' GM

NickD said:

Now that we live in a time of truck and SUVs, the height of a vertically-opposed engine isn't quite as big a problem. Plenty of room to cram it in there. I'm curious who will be the first to jam one in a Miata.

Turn it sideways, and does it take up more room than a Subaru six cylinder?

RossD said:

NickD said:

Now that we live in a time of truck and SUVs, the height of a vertically-opposed engine isn't quite as big a problem. Plenty of room to cram it in there. I'm curious who will be the first to jam one in a Miata.

Turn it sideways, and does it take up more room than a Subaru six cylinder?

Not sure. Problem there would be, it takes up power off the lower crankshaft for the torque converter/flywheel. So if you lay the engine on it's side, you would have to have a transmission with a weird offset bellhousing torque converter, because your flexplate is where one of the cylinder heads is on a Subaru. Maybe they could set it up to take power off the gear drive, but no clue if that would be robust enough, and then you would have to run the engine backwards to get the right rotation. (I think.)

The sound of it is also a consideration. For hardcore truck guys, it might be a selling point. "Hey, my new truck sounds like a big rig! Cool!" But for, say, a suburban mother running her daughter to dance class in a Ford Explorer, she's not going to put up with that.

That was my first thought as well, lay it down and you've got yourself a boxer (or a 180* vee) engine. Seems to me that it would be perfectly possible to drive the trans off that big gear drive with the right specification. Right now, it only carries half the load instead of the full load but we know how to make gears strong. Heck, that makes it part of your gearing and now you can run your transmission at a slower speed and have fewer inertial and frictional losses.

 Reverse rotation shouldn't be a problem. In fact, what's stopping you from running one of these backwards?

Keith Tanner said:

 Reverse rotation shouldn't be a problem. In fact, what's stopping you from running one of these backwards?

Oh, yeah. Duh. Two stroke! Hmmm, in theory they could do like some old golf-karts and just run the engine backwards for a reverse.

I wonder if  vertically-opposed is because Fairbanks-Morse is involved in the process, and that has been their thing since before WWII. Also, I suppose, ease of maintenance. If you lay it down and need to pull a crankshaft or pistons or rods, you are likely going to have to yank the engine out of the vehicle. Vertically opposed, you can, in theory, leave the engine in the vehicle and pull the lower crankshaft and rods and pistons out the bottom, and the upper crankshaft assembly out the top of the engine.

I doubt the 2.7 could be laid down really easily and still fit between shock towers. They've got 2 crankshafts instead of just one in the center like a Subie engine. It's pretty tall in the current layout The reason it's leaned over is because of the height when the cylinders were perfectly vertical. They had to lean it over to fit into normal truck engine bays.

But there is some precedent for the tech in a flat layout. Their big engine is laid flat, and has a central bell housing. Perhaps scaling something like this down:

Aramco? Why would the Saudi's want to save gas?

In reply to STM317 :

Hmm, tall and narrow you say. Seems like it'd be a perfect fit for a Wrangler or Gladiator. 

Also, I know that British Chieftain tanks use a horizontal opposed-piston 6-cylinder/12-piston multifuel engine.

In reply to pinchvalve :

They want to keep ICE viable as loooong as possible. 

Didn't the Commer diesel operate like this years go? 

spitfirebill said:

Didn't the Commer diesel operate like this years go? 

Similar in that it was opposed-piston, but it was horizontal and had a single crankshaft with some weird monkey-motion to hook the pistons to it. That was definitely a weird engine

In reply to NickD :

After I posted that I did a google search.  It seems someone is working on a new version of the Commer engine.  

FB couldn't compete with GM in railroad locomotives because GM had a modular and scalable solution.  Dig in to the 2 stroke GM "Detroit" and you'll walk away scratching your head and realizing that that wasn't designed by someone with a normal degree of intellect.  It's pure genius.

In reply to A 401 CJ :

There is a 2-71 for sale locally. I didnt know there were less than 6 cylinders.

https://www.facebook.com/marketplace/item/2871460539565852/

In reply to A 401 CJ :

Getting a bit off-topic, but FM's design did scare off a lot of buyers due to being too different. Railroads were notoriously conservative, and Alco, Baldwin and EMD all used the same basic design. FM's OP was like the rotary of the locomotive world. I know Southern Pacific tried to keep all of theirs assigned to the same district, where they had a crew that understood them and could keep them running.

They also tended to be a bit too powerful at an era where purchasers didn't seem.interested in high-horsepower (the H24-66's 2400hp wouldn't be matched by GM for another 9 years).

Ok. That's kinda neat.