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

[Steevo]

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

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.

 

[Frick]

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

 

[DeathtoGnomes]

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)

 

[Aquinus]

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.

 

[FordGT90Concept]

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.

 

[ne6togadno]

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

 

[CAPSLOCKSTUCK]

Brilliant link....nice one pal.

 

[ne6togadno]

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

 

[FordGT90Concept]

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.

 

[Aquinus]

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.

 

[revin]

variable compression engine

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

 

[Steevo]

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.

 

[Aquinus]

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.

 

[cornemuse]

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!)

 

[Jetster]

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

 

[Caring1]

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.