Have we talked about the Achates Power 2.7L?

GIRTHQUAKE said:

STM317 said:

NickD said:

morello159 said:

In reply to NickD :

Not quite as extreme, but my 2.7L gas f150 makes 325hp and 400ft-lbs... And that's just a regular old 4 stroke gas engine (with DI and turbos)

Seems like an interesting concept, but what's the advantage of having more pistons instead of just running a higher static compression ratio? Mazda's HCCI engine comes to mind. 

The advantage is less moving parts. Because it's two-stroke with an opposing-piston design, you can toss the entire valvetrain out. No timing chains, cam actuators, rocker arms, valves, valve springs, etc. The other advantage, and I have no clue how true this bit is, this is just what they are claiming, is that it supposedly will get 47mpg.

I think the most interesting thing about it, will be finding out if they can meet their power and fuel efficiency claims after somehow cleaning up a two stroke enough to meet modern emissions standards.

I'm just spitballing- i've never played with 2-strokes before- BUT...

Tossing out all the valvetrain means we only have rotational losses from driving the two cranks and the supercharger, and being twincharged it's constantly under boost for scavenging. Since each drop of fuel goes to pushing two pistons and the supercharger likely shuts off when the turbo comes on, I think the whole "50% more efficient" is totally believable.

With it constantly under boost you feasibly have constant air being pushed into the exhaust while it's still hot, which would allow any hydrocarbons to burn to CO2 similar to old EGR air pumps. The REAL question tho, is how the heck the drivetrain is being lubricated without putting oil into the gas unless A. it's a 2-stroke diesel or B. It's using E85 only, which CAN be a lubricant. I wonder if that EGR it points to is really some kind thermal reactor like on an old Mazda.

Huh, did some searching and found this statement from Achates

"When fuel is mixed oil, the oiling system is called a total loss system – API does not use total loss system due to emission and durability concerns. The Achates OP engine has conventional lube system, the oil is recirculated in a closed system, has an oil sump, pressurized oil system etc.
The engine oil requirement is defined by our customers, as well as the maintenance interval and durability targets – the requirement usually comes from current, state of the art 4-storke diesel engine for the same application. Our research engine (single and multi-cylinder) does use synthetic oil."

Weird. So it doesn't burn oil. Or at least not at the rate of a conventional 2-stroke.

Also, found this link from them that really gets into the oil consumption aspect and it really made my head spin. Stuff about super crazy piston rings and, and this is wild, using lasers to perform cylinder honing instead of a tradition abrasive.

http://achatespower.com/media-center/engine-design-videos/oil-consumption/

Here's the link if anyone wants to read it. Wowza.

penultimeta said:

So I'm going to be real honest and say I had no idea that vertically opposed engines existed until this thread started. I've just spent the better part of the last two days researching the Detroit 6v53t and, holy e36m3, I want that engine in everything. I don't care how heavy or unwieldy it is. It sounds magical. 

I told ya!

https://youtu.be/5Q7oYXx1CwQ

The glorious sounds of an unmuffled 6v53 Detroit!!!

In reply to NickD :

Frickin' Lazer Beams?

I also did some research because I got interested too- wikipedia's main article says that there are 2-strokes with typical wet oil-sump systems, but they can only achive this by using boost so they don't use the crankcase for the air intake. So that, coupled with direct injection solves the question of lubrication and how they're using normal gas. Here's some wikipedia deets.

Lotus, of all manufacturers, has also built some interesting, direct injected two strokes. 

So, this being GRM, these engines come out and somebody immediately wrecks a truck with one in it, what are we jamming the junkyard takeout engine into? Jeep Wrangler or Gladiator stands out to me, just for the packaging. Or maybe an old '30s Ford pickup truck. Close the hood and roll up to a car show with it making that noise, then pop the hood and watch people try and figure it out.

penultimeta said:

So I'm going to be real honest and say I had no idea that vertically opposed engines existed until this thread started. I've just spent the better part of the last two days researching the Detroit 6v53t and, holy e36m3, I want that engine in everything. I don't care how heavy or unwieldy it is. It sounds magical. 

If you want to go crazy with opposed piston engines, check out a Napier Deltic. Three opposed piston pairs, three crankshafts.

NickD said:

So, this being GRM, these engines come out and somebody immediately wrecks a truck with one in it, what are we jamming the junkyard takeout engine into? Jeep Wrangler or Gladiator stands out to me, just for the packaging. Or maybe an old '30s Ford pickup truck. Close the hood and roll up to a car show with it making that noise, then pop the hood and watch people try and figure it out.

With constant boost and wild sounds, we drop it into 1970 Mustang or Torino as a wild Mad Max clone 

NickD said:

I'm curious who will be the first to jam one in a Miata.

Send me an engine and transmission and I'll make it happen. ;P

AWSX1686 said:

NickD said:

I'm curious who will be the first to jam one in a Miata.

Send me an engine and transmission and I'll make it happen. ;P

If you did it, I bet 24 Hours Of LeMons will let you run in Class C instantly. 

STM317 said:

Sk1dmark said:

Couldn't help but notice at 2:34 he mentions that Achates (those making OP's 2.7) were the ones who tested a single cylinder (twin piston?) version of the Advanced Combat Engine. Maybe one is licensing the tech from the other?

Yes, that's why I posted that link. The ACE engine is a joint effort between Cummins and Achates. Compared to a small startup like Achates, Cummins has the funding, engineering prowess, manufacturing scale, and existing ties with the Military to actually bring the thing to fruition. 

There's also a lot of familiarity among the VIPs of the two companies as well. Achates CEO is a former Cummins exec. And so is their Chairman of the Board. So if the claims are true, and the tech has merit, perhaps something like this 2.7, or another opposed piston engine, would wear Cummins badging if it made it to market?

My apologies, I didn't realize that. Very interesting way for Achates to get some potentially great tech into a much broader market.

The weight of two crankshafts is more than camshafts...so it isn't going to be a lightweight engine, like a normal two stroke.

My 130hp 3-cylinder Kawasaki  jetski engine is 95lbs.    Yamaha has a 300hp v6 direct injection outboard motor 2 stroke.

DIrect injection 2 strokes solve all the problems with a two stroke, and let you turbocharge them as well,

I read that recently F1 is thinking of going with DI 2 strokes engines.

I wonder how smooth it is. With a power stroke every 120 degrees it should feel like an Inline 6, but do the opposed pistons counteract each other as well? IF they do, does that mean this will rev and feel similar to a V12?

nimblemotorsports said:

The weight of two crankshafts is more than camshafts...so it isn't going to be a lightweight engine, like a normal two stroke.

The weight comparison to a normal gas engine of similar displacment would be interesting. The 2 stroke has no cylinder head(s), camshaft(s), valves, valve springs, etc. Looks like just 3 fuel injectors too, instead of 6. 

But it's got 2 cranks with balancers, a supercharger and a turbo, and that big gear drive on the back. I'd bet it's +/-10% of a conventional gas engine.

nimblemotorsports said:

The weight of two crankshafts is more than camshafts...so it isn't going to be a lightweight engine, like a normal two stroke.

My 130hp 3-cylinder Kawasaki  jetski engine is 95lbs.    Yamaha has a 300hp v6 direct injection outboard motor 2 stroke.

 

DIrect injection 2 strokes solve all the problems with a two stroke, and let you turbocharge them as well,

I read that recently F1 is thinking of going with DI 2 strokes engines.

Don't compare land based engines to marine engines.  Those boat boys cheat.  They have a lake or ocean to dissipate heat.  We have lowly radiators.
 

Example:  bus grease monkey is one of my favorite YT channels now.  He's sort of a guru on Detroits.  In one of his episodes he gets hired to go down to Florida to work on a boat with 2 6-71 Detroit's.  The same 2 stroke 426 cubic engine his bus has.  His bus makes...was rated at...238 net hp.  If it were turbo, GM would have rated it 300.  What do you think just one of the lumps in the boat was rated for?   I think it was 450 if memory serves.  He laughed at the ridiculous size of the injectors.   

Detroits don't burn lubricating oil, since they have a supercharger to force air in through channels down the side of the crankcase.  A conventional two stroke uses the piston moving down in the crank case to create that pressure.

Direct injection would solve emissions issues, because you are not pressurising a fuel air mixture, so you can use the intake charge to shove the exhaust out as hard as you want.

That pair of cranks and the huge gear linking them together may have fewer moving parts, but it sure doesn't look simple to me.

Some large farm tractors in the late 50's were built with Jimmy diesels.  It would be the profoundly deaf retired farmers who owned them.

Streetwiseguy said:

Direct injection would solve emissions issues, because you are not pressurising a fuel air mixture, so you can use the intake charge to shove the exhaust out as hard as you want.

Seems like you'd still have NOx and particulate issues from the compression ignition though. Perhaps they're planning a diesel type aftertreatment system to handle that.

From what I understand, the real problem remaining of two strokes is the rings are pinned to the pistons and don't rotate, so the gap doesn't catch on the port edges,

and this makes them wear out relatively quickly compared to four strokes.  

Not an issue for racing.

Mr_Asa said:

A green two stroke gas engine?

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

I still don't see it.  It will have the same problem rotaries have with respect to catalyst life.  The engine will burn oil because the rings sweep over the ports, this oil will shorten converter life a lot.

A 401 CJ said:

Recon1342 said:

In reply to A 401 CJ :

Diesels have always had skewed HP to Torque numbers... Even the 4 strokes. A Cummins 4bt can make a whopping 190 HP and put out 450 lbft of torque.

I love two strokes because they sound cooler...

Sorry but it's not "skewed".  It's just maths.  It makes 190 hp at a relatively low rpm.  That translates to a high torque number.  

 

Once upon a time, when I was a skull full of mush beginning engineer, they took me onto the floor at USSteel Gary Works.  There was a GE motor there built in 1918.  300 hp.  So what?  300 hp at 18 (eighteen) rpm.  That's hideous torque.  It was a 3 story tall machine.  That got me thinking...how much torque would 1 hp at 1 rpm be?  I once did the calculation and don't feel like doing it again but it's a LOT!  Sorry for the rant.  I don't know much really but the relationship between hp and torque is one I never get tired of babbling on about  :-)  

5252 ft-lb?

GIRTHQUAKE said:Tossing out all the valvetrain means we only have rotational losses from driving the two cranks and the supercharger, and being twincharged it's constantly under boost for scavenging. Since each drop of fuel goes to pushing two pistons and the supercharger likely shuts off when the turbo comes on, I think the whole "50% more efficient" is totally believable.

I'd have to see it to believe it.  Camshaft friction has absolutely nothing on piston ring friction.  I saw a study a while back that said 1% of the world's energy production (including wind, solar, nuclear) was consumed by piston ring friction.

Another counterpoint:  Mazda rotaries.  They don't have valvetrain, and they make a lot less power for the same displacement - a rule of thumb is that a "1.3" (2.6l) engine is roughly equivalent to a 2 liter piston engine.  Turbocharger sizing needs to be roughly 20% larger for the same power output.  It's poor thermal efficiency and friction from all the seals.

The other thing that this engine has in common with a rotary is the very large straight-cut timing gears.  Old Mazdas with factory-quiet exhaust systems, but no modern "sensory deprivation chamber" interior sound deadening, had an engine note that was mostly comprised of a geary whine.  And that is with the gears being "internal" with a lot of iron in the way, as well as a second cover on the front and a bellhousing in the rear.  This thing, I bet, would have gear scream as its primary sound effect.  Don't get me wrong, I think that'd be pretty cool from a car-guy perspective, but it might not fly from a 2020 NVH expectations mindset.

In reply to Knurled. :

So if I combine it with a dogbox transmission I won't need a straight pipe to have other people hear me coming ?

I think I read something similar about piston ring losses somewhere. The detail about gears is a good one, but we still don't have one opened or heard outside of a tech demonstrator- but the weight of a crank I totally agree, I was more thinking of the losses in total from X part driving Y piece; but I am no expert by any means.

I was really hoping for some ring ta ting type E36 M3. Sounds gross. 

In reply to pinchvalve : cause they are running out and once it's gone they have no other way to fund their economy. I don't believe their reserves have been independently verified since the 70s.