The Opposed piston Diesel Engine is Back

[olddog]

For you gear heads that are interested in engine designs in general, this is interesting. So interesting, that the DOD handed Cummins $48 million to start putting them in military applications.

You may remember that Junkers 205 2 cycle opposed piston diesel engines went into large aircraft - bombers and cargo and passenger planes around WWII time frame.

Well the design is getting a new look with modern computer control technology. They claim it is more fuel efficient and has lower emissions than current engine designs.

Opposed-Piston - Achates

The power to weight ratio of typical diesel engines keep them out of air craft, but this design has a better power to weight ratio than many gasoline engines.

[95CobraR]

Why is Diesel important when Tesla is (maybe) going to make this a non-fossil fuel economy?

[Ron61]

For one thing the Telsa vehicles are way to expensive for most working people. And where are you going to charge one if you want to take a vacation or trip that exceeds their mileage limit. Try to find a place top recharge them every few hundred miles if you want to take a trip back East for example. And that long mileage claim dropped a great deal when they tried them in the mountains. I am not against electric vehicles. I just question how they are going to overcome these limitations. Also since the environmentalists refuse to let them build more power generating plants, where is the power to charge them going to come from and how much is it going to cost. We have been having power turned off to sections of the cities here for the past several years as the power grid is already overloaded.

Ron

[olddog]

Electric motors are heavy - power to weight is ugly. Price is high. This 250 Hp motor is $14000 and 2400 lb.

https://www.grainger.com/product/MAR...e-Motor-44Z676

To put into perspective what Ron said about the power grid. Let's assume we convert to electric powered cars. It takes about 30 Hp or 40 Kw to cruise down the road on level ground at around 60 mph. Much more to accelerate, but let's ignore that. So if on average ever person in this country were to cruise one hr in a car, five days a week, 52 weeks per year, we would use 40 * 5 * 52 = 10,400 KwH of electricity per capita on transportation, anually. I think we can agree this is a conservative number and it does not include transportation of goods (trucking). For the year 2015 the Per capita power consuption in the USA was 12,915 KwH. Bottom line reality is that for everyone to conver to electric cars we will have to double the size of the power grid. That or each individual will have to purchase there own windmill or solar cell to charge their own car.

https://en.wikipedia.org/wiki/Electr..._United_States

[95CobraR]

The recently announced Tesla Roadster is $250,000. It requires a immediate $5000 deposit via credit card with a $245,000 wire transfer in 10 days.

It may be delivered in 2020. What could go wrong?

[Buzz]

That Tesla roadster also accelerates from 0-60 in under 2 seconds and tops out around 250 mph. Check the prices on maybe two other production cars in the world that approach those numbers and the Tesla's price is bargain basement. You could buy a fleet of Teslas for the price of one Agera or Bugatti.

[95CobraR]

I'd say the car is not designed to go 250 Mph. It would flip after becoming airborne. BTW, a Bugatti can actually perform well on a road race track. His first Roadster had a total production of 2,500 cars.

Elon Musk is known to exaggerate on his press statements. Where are the 250,000 Model 3 cars that he said he would build by the end of 2017?

Oh, and he will also build big trucks by 2020. That should be interesting with no plant built yet.

[Buzz]

Originally Posted by 95CobraR

I'd say the car is not designed to go 250 Mph. It would flip after becoming airborne. BTW, a Bugatti can actually perform well on a road race track.

What on earth qualifies you to make that determination? Just because you want something to be true does not make it so. Granted it isn't tested yet but based on the performance of the Model S, at least the acceleration figures are entirely plausible.

BTW the point was in response to the comment on the Tesla's cost. The Bugatti Chiron costs $4 million - sixteen (16!) times the price of the Tesla, so it better damn well be able to perform well on the track!

Has Tesla had production delays? Absolutely - but building cars is difficult. Especially so for cars using alternative propulsion, performing well beyond conventional standards and built by a relatively new company. Imagine what electric car performance will be like in the next 10 years.

Back to the opposed piston diesel which is what perked my interest initially - I wonder if the better power to weight ratio will make them viable in the marine industry. Not sure if they come with inherent size/shape/configuration issues, but the prospect of a lighter, more powerful diesel powerplant is always an exciting to the sportfish/large express cruiser crowd.

[olddog]

Originally Posted by Buzz

Back to the opposed piston diesel which is what perked my interest initially - I wonder if the better power to weight ratio will make them viable in the marine industry. Not sure if they come with inherent size/shape/configuration issues, but the prospect of a lighter, more powerful diesel powerplant is always an exciting to the sportfish/large express cruiser crowd.

I read, a long time ago, where there were several large scale opposed piston 2 cycle diesels designs for large electrical power generation back in the day. Also the Germans built one huge 24 cylinder version. It had four crankshafts, with four cylinders forming a square with the crankshafts located at the corners. There were six rows of the four cylinder squares.

The most efficient marine diesels engines are 2 strokes. Somewhere in the neighborhood or 3 foot bore by 9 foot stroke. The rod is a complicated design to allow the long stroke not to hit the cylinder walls, with out being ridiculously long. The opposed piston would allow two 4.5 foot strokes. This would simplify the rod design and cut the piston speed in half, thus allowing a doubling of the rpm. I would think this would be revolutionary in large marine engines.

[Buzz]

Thanks olddog - I hope the marine industry is paying attention. Better power to weight ratio and higher operating RPM's could be a game changer in that market.

[olddog]

It could be a game changer in many applications. We put about $1500 in a set of heads, $200-300, for a set of rockers, likewise for a cam, and still have to buy a set of lifters and a push rods. I suspect about $2500 for heads with a total valve train. A rotating assembly is about $1200. So you could save about half the cost, going to the opposed piston design. This savings would go a long way toward paying for the blower, needed. It is a simpler design to assemble, with much fewer parts. Then you get better fuel efficiency and lower emissions. There is a lot to like about this engine.

On top of all that it can run on a lot of different fuels.

[Buzz]

This is really interesting - I'm going to to have to do some reading up and learning. Thanks for posting this - I'd love to hear more.

[95CobraR]

Originally Posted by Buzz

What on earth qualifies you to make that determination? Just because you want something to be true does not make it so. Granted it isn't tested yet but based on the performance of the Model S, at least the acceleration figures are entirely plausible.

I have actually raced cars for 25 years. I was there at Road Atlanta at the Petit LeMans when the MB car came out of T-7 onto the main straight and flipped. They withdrew both cars. Search 1998 Petit LeMan for the video.

The MB didn't have the down force for the speed.



You say that an untested roadster with only computer generated pictures can actually go 250 Mph? I don't think so.

[Buzz]

I was present in July 1986 when the Pope visited Saint Lucia - but that doesn't make me a biblical scholar. You claim to be able to predict a car's high-speed handling dynamics by looking at a picture because you've raced a bit and attended a race where one car crashed? - That's remarkable in several ways

The Tesla roadster is not just CG; it's a running, driving prototype that accelerates at a phenomenal rate. So let's say it only does what - 230?, 220? - That's still significant at 1/16th the price of its closest competitor performance-wise.

Enough about that, though - I'm reading up on and learning more ( ) about the opposed piston diesel engine. Improved efficiency through simplicity - no cylinder heads or valve train - amazing in this age of improvement through increased complexity and applied technology.