# WWII design is  revived to make a new type of engine that uses a third less fuel



## CAPSLOCKSTUCK (Dec 5, 2016)

San Diego-based Achates Power claims that its revitalised a different World War 2-era design that is cheaper, smaller, lighter, and could be 30 per cent  more fuel efficient.






Pictured is a graphic representation of three of the engine's opposed-piston cylinders. The blue gas is the injection of fuel and air, while the red gas is exhaust fumes.
http://achatespower.com/

'This engine is simple to manufacture, has few parts and is less costly [than conventional engines],' President and CEO of Achates power David Johnson told Wired.

Archates' design takes the car engine in a different direction. Its opposed piston engine works using two pistons in each cylinder instead of one.

Power is generated when the fuel and air mixture is ignited, driving the two pistons apart. Without the labyrinth of valves and camshafts of a conventional engine, the opposed piston engine is a much simpler and smoother design.


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## Jetster (Dec 5, 2016)

I dont see how a two stroke will be "inherently low emissions"  Every application of the two stroke motor including diesel has been historically dirty. Your mixing burnt and clean air together.


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## CAPSLOCKSTUCK (Dec 5, 2016)

A two-stroke engine produces twice as many power strokes per revolution as its four-stroke equivalent. This advantage leads to smaller displacement engines for similar performance, and lower in-cylinder pressure to lower emissions compared to four-stroke conventional engines.

http://achatespower.com/our-formula/opposed-piston/


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## Jetster (Dec 5, 2016)

CAPSLOCKSTUCK said:


> A two-stroke engine produces twice as many power strokes per revolution as its four-stroke equivalent. This advantage leads to smaller displacement engines for similar performance, and lower in-cylinder pressure to lower emissions compared to four-stroke conventional engines.
> 
> http://achatespower.com/our-formula/opposed-piston/



If that was true we would see them all over the place. The fact that they are being outlawed for the emissions proves it. I love two strokes but they are a dirty motor.


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## Jetster (Dec 5, 2016)

ignore


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## Jetster (Dec 5, 2016)

CAPSLOCKSTUCK said:


> A two-stroke engine produces twice as many power strokes per revolution as its four-stroke equivalent. This advantage leads to smaller displacement engines for similar performance, and lower in-cylinder pressure to lower emissions compared to four-stroke conventional engines.
> 
> http://achatespower.com/our-formula/opposed-piston/



I know too much about two stroke motors.  ( I use to be a marine mechanic) OMC But Iguess they figured some stuff out 

http://achatespower.com/wp-content/...iston_two-stroke_diesel_engine_advantages.pdf


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## CAPSLOCKSTUCK (Dec 5, 2016)

Thats the point of revisiting this design.  Burning 30% less fuel means a reduction in emissions. Also the way the gasses are exhausted. This vid explains it best i think.


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## Jetster (Dec 5, 2016)

You still have to get past mixing chamber inefficiencies. But I guess they did some how. 

Years ago they came out with what known as loop charge. They were able to get 300Hp out of 160 c.i with is crazy powerful


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## EarthDog (Dec 5, 2016)

Thanks for the thread. 

And holy triple post!!!


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## Jetster (Dec 5, 2016)

I dont know what happen


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## Ferrum Master (Dec 5, 2016)

Jetster said:


> I dont know what happen



Beer?


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## Jetster (Dec 5, 2016)

Ferrum Master said:


> Beer?



No, but that might help


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## newconroer (Dec 5, 2016)

CAPSLOCKSTUCK said:


> Thats the point of revisiting this design.  Burning 30% less fuel means a reduction in emissions. Also the way the gasses are exhausted. This vid explains it best i think.



Well at least it means that there's hope we'll have combustion engines for a little bit longer than expected with this green craze going on.

I mean, screw the homeless Vietnam veterans dying in gutters, we need to 'save the planet' for some strangers hundreds of years from now!


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## Jetster (Dec 5, 2016)

newconroer said:


> Well at least it means that there's hope we'll have combustion engines for a little bit longer than expected with this green craze going on.
> 
> I mean, screw the homeless Vietnam veterans dying in gutters, we need to 'save the planet' for some strangers hundreds of years from now!



There not as far along as they want to believe in the green tech. Oil will be around for many years. But if we can get China on board that would be cool


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## newconroer (Dec 5, 2016)

Jetster said:


> There not as far along as they want to believe in the green tech. Oil will be around for many years. But if we can get China on board that would be cool


Nah, they never are, but they make the rest of us normal people suffer the throat shoving nonsense, higher costs for things and increased regulations (lack of freedoms).

You'll struggle to find people who can quantify what it all means in their day to day life, unless they live in such horrendous conditions that the air has become toxic. Though something tells me that Billy Joe and his dirt bike riding friends aren't the culprit for Beijing's smog.
What also helps us fight off this green invasion, is that the car enthusiast market is massive and a large percentage will always love combustion and classic engines. 

I just hope it doesn't become an antique market.


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## Jetster (Dec 5, 2016)

I'm still pissed at Tesla with its government subsidies producing a $80,000 electric car that only wealthy people that don't pay taxes can afford


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## newconroer (Dec 5, 2016)

Some type of irony in that isn't there?

Though overall this type of engine modification is awesome. Cool stuff for sure.


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## TheMailMan78 (Dec 5, 2016)

Jetster said:


> If that was true we would see them all over the place. The fact that they are being outlawed for the *emotions* proves it. I love two strokes but they are a dirty motor.


I've been banned before, for to many emotions. However I am WAY MORE than two stroke.


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## thebluebumblebee (Dec 5, 2016)

Jetster said:


> I'm pissed at ... government subsidies


Hey, me too!


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## Steevo (Dec 6, 2016)

CAPSLOCKSTUCK said:


> San Diego-based Achates Power claims that its revitalised a different World War 2-era design that is cheaper, smaller, lighter, and could be 30 per cent  more fuel efficient.
> 
> 
> 
> ...




The biggest issue is there is MORE rotating mass and wearing surfaces, so you halve the MTBF and unless the engine is going to be mounted like a boxer engine, (which already has oil management issues) you won't be running too long as the cylinders will fill with oil on the top and start all sorts of fun. 

I bet there is a reason why good engineers haven't used this design, for example, if its forced induction how do we prevent excess fuel from entering the exhaust and burning up a turbo (unless we direct inject it, kinda like they show,)? Direct injection has its own problems with an engine like this, first being how much pressure is in the cylinder as a lot of air blows out from inlet pressure, and all of the features they claim to have, can be overcome by direct valve actuation and or forced induction.


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## Aquinus (Dec 6, 2016)

Steevo said:


> The biggest issue is there is MORE rotating mass and wearing surfaces, so you halve the MTBF and unless the engine is going to be mounted like a boxer engine, (which already has oil management issues) you won't be running too long as the cylinders will fill with oil on the top and start all sorts of fun.
> 
> I bet there is a reason why good engineers haven't used this design, for example, if its forced induction how do we prevent excess fuel from entering the exhaust and burning up a turbo (unless we direct inject it, kinda like they show,)? Direct injection has its own problems with an engine like this, first being how much pressure is in the cylinder as a lot of air blows out from inlet pressure, and all of the features they claim to have, can be overcome by direct valve actuation and or forced induction.


Balancing such an engine would be a bitch. I love the flat-4 in my Subaru Impreza. Naturally balanced. 

...and for the record, I almost never have to put extra oil in my car. They revised the piston ring design in 2014 I think (mine is a 2015.)

Edit: This looks different than the designs I've seen in the past where the second piston is moving a different speed on a different crank to radically alter the compression cycle. This appears to be a bit different than that. I assumed its balance would suck because I thought it was another kind. My bad.

Edit 2: I was thinking about this: https://en.wikipedia.org/wiki/Six-stroke_engine


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## erocker (Dec 6, 2016)

It's still going to puke dirty smoke out of it. I'm sure they'll do something smart like adding catalysts to it to negate any kind of efficiency it really has.


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## slozomby (Dec 6, 2016)

erocker said:


> It's still going to puke dirty smoke out of it. I'm sure they'll do something smart like adding catalysts to it to negate any kind of efficiency it really has.


several things have changed since 2stroke was popular.
low-sulfur/biodiesel has become more prevalent.
O2 sensors in exhaust allowing for more accurate Fuel/Air mixtures and recycling of unburnt fuel in exhaust.

just being able to adjust the fuel/air ratio on the fly is a huge gain in emission improvement over the stuff we used to have.

while cats do restrict airflow the gain in performance by removing them isn't all that its cracked up to be on a properly tuned engine. or rather i can say it had less than a 10% improvement on my '09 fatbob. the biggest limitation on power from the stock bike was getting rid of the crappy CARB mandated fuel mapping(tuned before and after the cat removal).


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## Aquinus (Dec 6, 2016)

slozomby said:


> recycling of unburnt fuel in exhaust.


That's a pretty important one in 2-stroke engine and that usually limits you to a pretty narrow power band. With modern engine with things like variable valve time and variable valve lift (or both,) you get a lot better efficiency than you did with just ignition timing alone. I honestly thing that getting rid of valves is a mistake and that solenoid actuated valves is what's going to get us the most benefits.


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## slozomby (Dec 6, 2016)

Aquinus said:


> That's a pretty important one in 2-stroke engine and that usually limits you to a pretty narrow power band.


the smaller power band is less of an issue in more modern transmissions with much better shifting patterns and additional gears.

additionally in more static rpm applications like an electric vehicle with a generator to charge from this is also not really an issue.


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## Steevo (Dec 6, 2016)

Aquinus said:


> Balancing such an engine would be a bitch. I love the flat-4 in my Subaru Impreza. Naturally balanced.
> 
> ...and for the record, I almost never have to put extra oil in my car. They revised the piston ring design in 2014 I think (mine is a 2015.)
> 
> ...




I rented a 2015 Scubaru Outback last year for a 4K mile trip and it still managed to burn a quart and a half, 9700 miles on it when I put the key in, and all of them still use some oil as they age. Its not bad, but imagine if pistons were upside down, the bottom would fill with oil, and it would run past the rings, clog up rings and throw off the balance of the engine.


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## Frick (Dec 6, 2016)

newconroer said:


> Well at least it means that there's hope we'll have combustion engines for a little bit longer than expected with this green craze going on.
> 
> I mean, screw the homeless Vietnam veterans dying in gutters, we need to 'save the planet' for some strangers hundreds of years from now!



Everone's a stranger, kill your family, burn the world, be a man


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## DeathtoGnomes (Dec 6, 2016)

I was a diesel mechanic for a few years, I watched the trucking field evolve from full on mechanical everything down to the gauges, all the way to what it is now, almost fully computerized. 2 strokes of the past, notably Detroit Diesels are still around.

The problem with 2 strokes was noise and emissions due to incomplete fuel burning, something that even fuel injection cant fully fix. Incomplete burning depends mostly on the piston stroke length, the better you can keep the gasses contained the more efficient burn you get, but with need for more power and torque, emissions were sacrificed and so suffered the hits.

here is a Detroit Diesel 2 stroke cylinder sleeve, the "perforation" is the exhaust port. Cylinders heads have the valves to provide intake air.






(depending on the motor size specs that could get over 20  inches tall)


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## Aquinus (Dec 6, 2016)

Steevo said:


> I rented a 2015 Scubaru Outback last year for a 4K mile trip and it still managed to burn a quart and a half, 9700 miles on it when I put the key in, and all of them still use some oil as they age. Its not bad, but imagine if pistons were upside down, the bottom would fill with oil, and it would run past the rings, clog up rings and throw off the balance of the engine.


I would be careful about judging rentals since if they've never changed the oil on it, it's supposed to be changed every 6k and old oil will wear down the rings a lot faster on these cars. The Impreza also has a different engine than the Outback which has the FB25 whereas the Impreza has the FB20. I'm not sure if the FB25 has been revised but, the FB20 was with respect to piston rings. In addition to that, the FB20 is also a weird animal in the Subaru world because it's under-square (90mm stroke, 84mm bore.) whereas most engines Subaru produces (including the FB25 which is 90mm stroke, 94mm bore,) are oversquare (the FA20 and FA20DIT are square which are an exception.) If you literally take the FB25 and shrink the bore, you have the FB20. Less bore means less piston ring area which means less friction and less area for oil to seep through. On the opposite side of things, longer stroke means higher inertial forces during each stroke but, all in all, I've been happy with mine.

So, while I respect your experience with your rental, my 2015 Impreza has 38k miles on it, all of which (other than 38 miles,) I put on it. I've religiously kept up with maintenance and have never been later than 200 miles for one and my observation has been that more often than not, I don't need to add extra oil between changes. The exception to that is if I go on long rigerous drives, such as going through the mountains in NH and Maine for a 5 hour drive to go on vacation but, general usage doesn't give me that kind of behavior.


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## FordGT90Concept (Dec 6, 2016)

newconroer said:


> Well at least it means that there's hope we'll have combustion engines for a little bit longer than expected with this green craze going on.


Might be why they're taking a second look at it.  Two pistons should be able to produce higher compression ratios which translates to a more complete burning of the fuel so there's less exhaust  emissions clean up to do.

One of the big Asian manufacturers (forget who) is going to debut a variable compression engine soon (can increase/decrease the pushrod length on demand).  Opposed pistons would be taking that to the next level.


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## ne6togadno (Dec 6, 2016)

Aquinus said:


> Balancing such an engine would be a bitch. I love the flat-4 in my Subaru Impreza. Naturally balanced.


sorry that i have to dissapoint you buy engine of your subaru isnt nauturaly balanced. only 6 cylinder flat requires minmal amount of couter weights on crankshaft  in odered to be balanced. every other confinguration (beside radials) requires more counter weights for balancing.

@CAPSLOCKSTUCK
Jumo 205


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## CAPSLOCKSTUCK (Dec 6, 2016)

Brilliant link....nice one pal.


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## ne6togadno (Dec 6, 2016)

CAPSLOCKSTUCK said:


> Brilliant link....nice one pal.


if you make your way to 88046 Friedrichshafen, DE you can visit http://www.dorniermuseum.de/ and see it with your own eyes. behind glass panel though


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## FordGT90Concept (Dec 6, 2016)

The pros and cons of the Jumo 205 appears to match the new engines.  It says explicitly that the engine has to be vertically mounted because of the oil system.  It didn't cut down on vibration either because the two crankshafts are offset a little in timing for intake and exhaust.


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## Aquinus (Dec 6, 2016)

ne6togadno said:


> sorry that i have to dissapoint you buy engine of your subaru isnt nauturaly balanced.


It has a slight rocking imbalance because the cylinders are on different crank pins, that is true but that's about it IIRC. I don't think they do anything to counteract it because it's minor enough to be absorbed by engine mounts and transmission. The only 4 cylinder engine with more inherent balance than a Subaru flat-4 would be something like a Porsche flat-4 with shared crank pins or a 180° V4 if you will.


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## revin (Dec 6, 2016)

FordGT90Concept said:


> variable compression engine


*Infinity, * Seen this a while back and thought that's pretty cool !


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## Steevo (Dec 7, 2016)

Aquinus said:


> The exception to that is if I go on long rigerous drives, such as going through the mountains in NH and Maine for a 5 hour drive to go on vacation but, general usage doesn't give me that kind of behavior.




I drove the coastal highway and had it sliding through the redwoods too. It was being driven very rigorously. 

http://www.caranddriver.com/features/the-physics-of-engine-cylinder-bank-angles-feature

All engines are misbalanced at some point in the rotation, its just how much, and do you want to spend money for countershafts and or external balancing.


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## Aquinus (Dec 7, 2016)

Steevo said:


> I drove the coastal highway and had it sliding through the redwoods too. It was being driven very rigorously.
> 
> http://www.caranddriver.com/features/the-physics-of-engine-cylinder-bank-angles-feature
> 
> All engines are misbalanced at some point in the rotation, its just how much, and do you want to spend money for countershafts and or external balancing.


Driving them hard will burn oil a lot faster and will darken up the oil a lot faster too. Mine is a standard and I have a habit of not revving the engine as high but opening the throttle to about 3/4 to accelerate (with no traffic,) and it works out well for me but, if I did that with an automatic it would naturally rev higher due to the ECU's calculated demand from the accelerator peddle so I think it's rev-ing the boxer up that makes it consume a lot more oil than anything else but, that's just speculation. 

As for the link, it even says:


> A flat (“180-degree V”) engine, such as a Subaru four-cylinder, also can be perfectly balanced. To counter the rotational and reciprocating forces, the cylinders in one bank move in exact opposition to those of the other, thereby completely canceling the forces created by each.
> ...
> For example, a four-cylinder would like to fire at every 180 degrees of crankshaft rotation (720/4=180). Having firing events that occur in equal increments, as in this instance, is best for balance. The flat-four fires at 180-degree intervals, and its V angle is 180 degrees, which leads to a balance of firing forces. The flat-four, in fact, balances all three of the different types of forces.


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## cornemuse (Dec 7, 2016)

I operated heavy equipment with 'Detroit Diesel' engines, (see Post #28, above).Another problem with them was if you lugged them way down below normal idle, occaisionally they would run backwards, talk about SMOKE coming out the air intake!

(I'm retired, computers are really neat toys!)


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## Jetster (Dec 7, 2016)

cornemuse said:


> I operated heavy equipment with 'Detroit Diesel' engines, (see Post #28, above).Another problem with them was if you lugged them way down below normal idle, occaisionally they would run backwards, talk about SMOKE coming out the air intake!
> 
> (I'm retired, computers are really neat toys!)



I've actually done that. Us to drive an old tanker with a Silver 92 back in the 80's


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## Caring1 (Dec 8, 2016)

cornemuse said:


> I operated heavy equipment with 'Detroit Diesel' engines, (see Post #28, above).Another problem with them was if you lugged them way down below normal idle, occaisionally they would run backwards, talk about SMOKE coming out the air intake!
> 
> (I'm retired, computers are really neat toys!)


Usually from the timing being to retarded, it caused run on.
Great way to stuff up an engine.


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