Two cylinder, four piston engine in development - PeachParts Mercedes-Benz Forum

Cr from Texas · #1 02-14-2011, 01:56 PM

Sorry if this has been posted before but I found it very interesting.
Army TARDEC is looking at this DARPA developed engine. The video is 2 years old so, if progress continues, this should be nearing a useable prototype.
This is no wimp engine.
It's a two cylinder with four pistons delivering 300+ Horse Power
It's extremely small and very efficient and is presently in use in test applications
The configuration below is equivalent to a extremely ballsy four cylinder engine
When doubled, it's an extremely ballsy 600+ H.P. engine

It’s called OPOC (Opposed Piston Opposed Cylinder), and it’s a turbocharged two-stroke, two-cylinder, with four pistons, two in each cylinder, that will run on gasoline, diesel or ethanol. The two pistons, inside a single cylinder, pump toward and away from each other, thus allowing a cycle to be completed twice as quickly as a conventional engine while balancing it's own loads.
The heavy lifting for this unconventional concept was performed Prof. Peter Hofbauer. During his 20 years at VW, Hofbauer headed up, among other things, development of VW’s first diesel engine and the VR6.
The OPOC has been in development for several years, and the company claims it’s 30 percent lighter, one quarter the size and achieves 50 percent better fuel economy than a conventional turbo diesel engine.
They’re predicting 100 MPG in a conventional car.
For a good demo, See:
http://www.engineeringtv.com/video/Opposed-Piston-Opposed-Cylinder

dagObx · #2 02-14-2011, 03:10 PM

Weird! Combination of the old Detroit Diesel & Subaru. Interesting, tho....

W124 E300D · #3 02-14-2011, 05:31 PM

basically what Leyland did in 1970, and it was old hat then

http://www.youtube.com/watch?v=w0opl1wdYzE

Stevo · #4 02-14-2011, 06:33 PM

Same idea as the old Fairbanks-Mores two cycle engines. Thats not a valve cover on top, its a crank cover

http://www.tugboatenthusiastsociety.org/Pages/tugmach-diesel-modern-FM.htm

layback40 · #5 02-14-2011, 07:28 PM

There is always some one trying to invent a better mouse trap or clothes peg. Looks like they have moved on to motors.

vstech · #6 02-14-2011, 07:37 PM

it's been posted before. cool. I think Bill Gates is involved in it.

SD Blue · #7 02-14-2011, 08:33 PM

Hmmm............Here's a WWII Junkers opposed-piston diesel engine:http://www.billzilla.org/Junkers1.jpg

Also, a UK company: http://www.dair.co.uk/

Imagine the capabilities of a 200lb engine that puts out 100hp.

The ideas have been around for many years but the significant hurdle may not be the technology but instead the cost of tooling up and bringing into production such significant changes in design. The other significant hurdle is marketing new technology that has the high price tag of a vehicle. I wonder how many units have to be delivered before the cost of producing new technology ever pays off. Look how long direct fuel injection was around before it became widespread and literally replaced carberation. It seems to me that a lot of this technology starts out in aviation and smaller car manufacturers long before it becomes a mainstay of production in major manufacturers. It is significant that someone as large as Volkswagen is leaning in that direction.

W124 E300D · #8 02-15-2011, 05:37 AM

Quote:

Originally Posted by SD Blue

Imagine the capabilities of a 200lb engine that puts out 100hp.

BHP is bull****.
BHP is RPM
BHP is the rate at which the engine can consume fuel.

***TORQUE*** is work.

These are both approx 100 BHP engines, which means they both burn fuel at the same rate, nothing else, which one will power a loaded truck?

SD Blue · #9 02-15-2011, 05:51 PM

Hmmm............I don't believe a loaded truck was mentioned. The 100hp engine is an aircraft engine and the site doesn't mention the torque ratings. Anyway, 200# and 100hp certainly would fit in smaller vehicles.

josha37 · #10 02-15-2011, 05:59 PM

unfortunatly you are wrong with thinking hp is bs. Hp is just a function of torque x rpm and so it is safe to say if you have two engines with simliar torque and one has higher hp it will be a more efficient and powerful engine. While torque is very good at determining if you can get something moving hp is a much better way of estimating how fast it will be. so in your example of a large generator it is true that hp does not mater since it basically never accelerates anything just maintains a set speed, but if that power plant was in a large truck it would be useless.

bhp is brake horse power not fuel consumption rate that is bsfc or brake specific fuel consumption.

And do you want to explain how a large 8 cylinder burns the same amount of fuel as a small 2 cyl? rate fuel is consumed is easier to compare to cubic inches than it is to hp.

W124 E300D · #11 02-15-2011, 06:55 PM

Quote:

Originally Posted by josha37

unfortunatly you are wrong with thinking hp is bs. Hp is just a function of torque x rpm and so it is safe to say if you have two engines with simliar torque and one has higher hp it will be a more efficient and powerful engine. While torque is very good at determining if you can get something moving hp is a much better way of estimating how fast it will be. so in your example of a large generator it is true that hp does not mater since it basically never accelerates anything just maintains a set speed, but if that power plant was in a large truck it would be useless.

bhp is brake horse power not fuel consumption rate that is bsfc or brake specific fuel consumption.

And do you want to explain how a large 8 cylinder burns the same amount of fuel as a small 2 cyl? rate fuel is consumed is easier to compare to cubic inches than it is to hp.

Unfortunately I'm right.

The correlation between BHP and fuel consumption (for engines of a similar efficiency, e.g. IC to IC, not IC to turbine) is *remarkably* close, and to anyone with a brain it has to be remarkably close, because after all fuel consumption is no more than Btu per gallon vs how quickly it slurps a gallon.

You are confusing "power" (BHP or kW) with "work" (ft/lbs/sec) because basically you don't know the difference between the two.

"My buddy says his mopar will do the quarter mile in 14 seconds, but I reckon it's all torque"

was taught for a reason, as was

"You buy the horsepower, you drive the torque."

BHP just tells you your fuel bill, like kW just tells you your electric bill.

foot pound sec tells you how much WORK you are going to do, and therefore your ACTUAL efficiency.

Go ahead, do the math, work out how many kwh there are in a gallon of gas and diesel, then work out fuel consumption at rated hp for various engines, plot it all on a graph and it always comes out the same...

and the 100 bhp motorcycle engine still aint the 100 bhp gardner diesel, even though BOTH WILL CONSUME FUEL AT THE SAME RATE near as dammit.

josha37 · #12 02-15-2011, 07:23 PM

Torque does tell you how much work you are going to do but hp tells us all how fast you are going to do it. that is if we have to be simple and use old sayings. Im not going to argue with you because it is not only off topic but i dont feel like beating my head against a wall for the next couple days, go try drag racing a semi truck and let me know how many geo metro's beat you.

W124 E300D · #13 02-15-2011, 09:16 PM

Quote:

Originally Posted by josha37

Torque does tell you how much work you are going to do but hp tells us all how fast you are going to do it.

no, it doesn't...

a decent 30' waterwheel will produce 30,000 foot pounds of torque at 60 RPM, so BHP = (30 x 30,000)/5252 = 171 BHP

A generic Ford 6D diesel will produce 175 BHp @ 2,500 rpm, which means 365 ft/lb which is about right from memory.

Now anyone who thinks 30k foot pounds is in any way comparable to 300 foot pounds is a bloody idiot... those waterwheels drove whole floors full of line shafting driving scores of machines.

THIS IS EXACTLY WHY THE ORIGINAL Savery / Watt definition, WHICH WAS A SALES GIMMICK caused so many arguments and so many problems....

their definition was 33k foot pounds a minute for a dray horse, today's 746 watts, (WATTS, get it?) which would rate the 30' water wheel at 54 BHP

Basically Watt and everyone else were trying to sell their new, improved steam engines, which ran at a higher rpm than anything else on the planet, and so produced relatively little torque, and so WERE THE FIRST DEVICES ON THE PLANET THAT REQUIRED GEARING DOWN and not UP, with all the attendant losses, complication and expense.

to do that they had to artificially inflate the "power" of their product compared to the competition, sound familiar?

***YES*** going faster / working harder requires more fuel be consumed, but consuming fuel to produce torque and consuming fuel to produce bhp are not equivalent, just related.

Quote:

that is if we have to be simple and use old sayings. Im not going to argue with you because it is not only off topic but i dont feel like beating my head against a wall for the next couple days, go try drag racing a semi truck and let me know how many geo metro's beat you.

See, this is why you are an idiot, you refuse to listen, you refuse to think, you refuse the opportunity and invitation you were given by me to put up a graph and prove me wrong.

Gardner 6LXB 127 BHP @ 1500 RPM 10.45 litre straight six diesel will consume 5 gallons and hour on full song.

You can work out the torque yourself... (rpm x ft/lb)/5252 etc

That's approx 25 BHP per gallon per hour.

The BMW K100 motorcycle produces 90 BHP @ 8000 RPM, and will consume 3.5 gallons of fuel and hour on full song.

That's approx 26 BHP per gallon per hour.

Given 129 (diesel) to 114 (gasoline) thousand btu per gallon for the respective fuels we're still in spitting distance.

Now, because you refuse to do the math (funny that) I'll do it for you.

127 BHP @ 1500 RPM = 445 ft/lb
90 BHP @ 8000 RPM = 59 ft/lb

Which is why the Gardner will literally pull a truck while burning fuel at the rate of 25 BHP per gallon per hour, and the motorbike wouldn't pull the skin off milk at 26 BHP per gallon per hour.

What you CAN do is get that motocycle down the 1/4 mile quicker with a small, LIGHTWEIGHT, revvy engine, but that is a special case (drag racing) where you are more interested in ft/lb per lb of engine weight where the bmw mcycle engine blows the tits off the gardner diesel.

but that isn't "work"

it only becomes "work" when the start line mass of every vehicle in the drag race is identical, which is why drag races are run in classes, no stock car is ever going to beat a rail....

strelnik · #14 02-15-2011, 10:01 PM

Quote:

Originally Posted by Cr from Texas

Sorry if this has been posted before but I found it very interesting.
Army TARDEC is looking at this DARPA developed engine. The video is 2 years old so, if progress continues, this should be nearing a useable prototype.
This is no wimp engine.
It's a two cylinder with four pistons delivering 300+ Horse Power
It's extremely small and very efficient and is presently in use in test applications
The configuration below is equivalent to a extremely ballsy four cylinder engine
When doubled, it's an extremely ballsy 600+ H.P. engine

It’s called OPOC (Opposed Piston Opposed Cylinder), and it’s a turbocharged two-stroke, two-cylinder, with four pistons, two in each cylinder, that will run on gasoline, diesel or ethanol. The two pistons, inside a single cylinder, pump toward and away from each other, thus allowing a cycle to be completed twice as quickly as a conventional engine while balancing it's own loads.
The heavy lifting for this unconventional concept was performed Prof. Peter Hofbauer. During his 20 years at VW, Hofbauer headed up, among other things, development of VW’s first diesel engine and the VR6.
The OPOC has been in development for several years, and the company claims it’s 30 percent lighter, one quarter the size and achieves 50 percent better fuel economy than a conventional turbo diesel engine.
They’re predicting 100 MPG in a conventional car.
For a good demo, See:
http://www.engineeringtv.com/video/Opposed-Piston-Opposed-Cylinder

I wrote an article on this for the Army a while back.

josha37 · #15 02-15-2011, 10:21 PM

It is nice to see that your defense is simply to attack me while rambling on about fuel efficiency. Comparing the fuel usage and performance stats of a engine designed with a operating range of around 1000 rpm to one with a operating range that stretches 4-5k is hardly a comparrison worth making. Just like comparing a engine designed to move mountains to one designed to be a toy.