SoylentNews is people
SoylentNews
Submitted via IRC for SoyCow1984
Horizontally-opposed engines are often referred to as “boxer” engines because the motion of the pistons sort of resembles a boxer, punching. Really, though, if any engine should be named for a boxer, it’s the other kind of opposed engine: the kind where the pistons actually “punch” right at each other. They’re called opposed-piston engines, and they’re fascinating.
Opposed-piston engines are not new at all; they’ve been around since the late 1800s, and even earlier in steam form. In fact, the famous Civil War ironclad USS Monitor used a variant of an opposed-piston engine known as a “vibrating lever” engine.
Essentially, an opposed-piston internal combustion engine is a two-stroke engine with no cylinder head, two separate crankshafts, onto which two sets of pistons are connected, with the pistons sharing one cylinder.
The pistons meet (well, nearly meet) at the center of the cylinder, the top dead center (TDC) for both pistons. ports on the sides of the cylinder let fuel/air in and exhaust out, and are exposed by the motion of the piston.
[...] What’s especially notable about the engines is that, in three-cylinder (remember, six-piston) form, the Achates Power vertically-oriented opposed-piston diesel engine shown in the video there managed to obtain thermal efficiencies in the high 40s/low 50s percent. Keep in mind that a conventional four-stroke diesel engine will only be about 35 percent thermally efficient, on average. That’s a big bump.
Source: https://jalopnik.com/its-time-to-learn-about-wonderful-and-weird-opposed-pis-1827804895
(Score: 2) by AndyTheAbsurd on Thursday July 26 2018, @07:41PM (11 children)
I understand that the two-cycle version is going to be simpler (and therefore more reliable), but I do wonder if a four-stroke version of this engine is possible by placing the valves at the center point where the pistons almost meet. As I understand it, two-cycle engines are great for when you want high RPM and don't care about pollution - and given that latter item, I think there's a very low likelyhood that these would ever see widespread automotive applications unless a four-stroke version is developed.
Please note my username before responding. You may have been trolled.
(Score: 3, Interesting) by JoeMerchant on Thursday July 26 2018, @08:03PM (9 children)
They've had 100+ years opportunity to be developed, but efficiency wasn't that important in the past.
I don't see the packaging problem, as long as it fits between the front wheels converting two driveshafts into a single output shaft is not complex or demanding of volume.
Intake on the top, exhaust on the bottom, and the serpentine belt to drive the accessories can have two drive pulleys. Might want oval/vertically elongated cylinders for more displacement... would be a fun prototyping exercise, especially with CNC machining - but not cheap to tool up into mass production.
🌻🌻 [google.com]
(Score: 1, Insightful) by Anonymous Coward on Thursday July 26 2018, @08:14PM (8 children)
At least in USA, I claim efficiency isn't that important either--based on how people vote with their wallets. Note the shift to trucks/SUVs for well over half the sales of new vehicles. There is the question of the USA CAFE fuel economy rules (which are more easily met with small cars), but I predict one of Trump's last gasps (before he's out on his ear) will be to relax CAFE for a few more years.
Me, I like small cars. I feel stupid in a large vehicle, using something many times my weight/size to carry me around just seems wrong, on so many levels.
(Score: 0) by Anonymous Coward on Thursday July 26 2018, @11:46PM (5 children)
Most people were not paying attention.
Sure, the required number went up... but you no longer really had to meet that number. There was a huge fuel economy bonus multiplier available, and all that was required was to make the fuel system tolerate a bit more ethanol in the fuel. (meaning it doesn't get corroded metal and crumbly rubber)
Switching all fuel systems to earn the bonus would let a manufacturer meet CAFE rules with a lower number than before. Thanks Obama! Seriously I guess, because I like fuel systems that don't crumble and corrode.
(Score: 2) by JoeMerchant on Friday July 27 2018, @12:28AM (4 children)
Our local station started carrying E50 or somesuch, at a considerable discount - like 2.09 when regular is selling for 2.69. Not sure what all kickbacks are in play with that, but if you live in your car it could make a difference.
🌻🌻 [google.com]
(Score: 2) by urza9814 on Friday July 27 2018, @01:43PM (3 children)
It's not cheaper because of kickbacks necessarily (although there's some farming subsidies at play I'm sure)...but when I've looked into this stuff in the past I found it was priced pretty comparable to its relative value compared to normal gasoline. I dunno about E50, but E85 can be expected to cause a decrease in fuel economy of up to 27%. 60 cents off of $2.69 is a 22% discount. So it could save you a bit of money if your car is properly tuned for it, but the savings aren't going to be huge. And you'll have to stop and refuel more often -- a full tank won't get your as far.
(Score: 2) by JoeMerchant on Friday July 27 2018, @02:38PM (2 children)
While I agree that there is less energy content per gallon in ethanol than gasoline, it seems unlikely that substituting 15% of your gasoline with ethanol will decrease economy 27%.
🌻🌻 [google.com]
(Score: 2) by urza9814 on Friday July 27 2018, @03:41PM (1 child)
Ah, sorry, perhaps I should have explained that a bit more...E85 isn't 15% ethanol, it's 85% ethanol. I haven't seen E50 and I couldn't easily find numbers for E50, but the US Dept. of Energy states that E85 will decrease your fuel efficiency by up to 27%: https://www.fueleconomy.gov/feg/ethanol.shtml [fueleconomy.gov]
So E50 is about halfway between the standard E10 and that E85, so that could probably drop your fuel efficiency by close to 14%. With a given 22% savings on the price of it, it's still not a terrible deal if you're passing that gas station anyway, but it's not worth going too far out of your way for it. Although YMMV, quite literally...it's going to be a better deal for some vehicles than others.
The root of my comment is that I own a "flex fuel" Pontiac G6 which is designed to be able to run on E85. A couple years back I was testing out some gas finder app and saw a place selling E85 for what *appeared* to be a great price just a few towns over, so I decided to look up efficiency numbers for my car specifically. I don't recall the exact details, but I do remember that the cost savings and the expected reduction in fuel economy were within one or two percentage points of each other. So I've never actually put E85 in my tank, because with those numbers it wouldn't have been worth going even a mile out of my way to find some.
(Score: 2) by JoeMerchant on Friday July 27 2018, @04:31PM
O.K. - thanks - E85 was twisting my brain a bit... obviously.
It may actually be E85 that they are selling at that super cheap pump - it's a weird station, different pumps sell different mixes all up and down the range - not just 4 or 5 choices at each pump, but actually different choices depending on which pump you pull up to.
As far as energy density goes, diesel used to be the deal - up until the Gulf War II fuel price spikes, then they started actually charging for the value of it.
🌻🌻 [google.com]
(Score: 2) by JoeMerchant on Friday July 27 2018, @12:31AM
I've been impressed with some of the modern SUV's I've rented: big as a whale and gets 30mpg at 80mph. Still not worth the entry price, but those chilled seats were nice. I think that one had VD (most hillarious marketing gaffe of the past 30 years: Variable Displacement.)
🌻🌻 [google.com]
(Score: 3, Insightful) by urza9814 on Friday July 27 2018, @03:58PM
That's a bit of a self-fulfilling prophecy though. My mother just got a new SUV -- a Nissan Rogue. Before that she had a Subaru Forester. Neither time was she actually trying to buy an SUV -- she was looking for a hatchback wagon, which is how she ended up with a Subaru the first time. She was trying to find something small, but with enough cargo space that she could run the dogs down the the lake or go pick up a stack of 2x4s from Lowes. The problem is...nobody sells those anymore. So people in that situation end up with an SUV by default -- A decent number of those SUV sales aren't "voting" for big huge vehicles, they're voting for a passenger vehicle with cargo space.
(Score: 5, Interesting) by LoRdTAW on Thursday July 26 2018, @10:29PM
This is why I can't stand sites like Jalopnik, shitty writing for the sake of writing an article to generate page hits. Guess this person never heard of the Detroit Diesel 2 strokes. You could find the Series 53, 71 and 92 in shit loads of 60's/70's/80's trucks. In fact, the sound of a 6V92 is the standard TV/hollywood bus sound they dub in. Anyone who has sat in a GMC bus knows that sound and the big clouds of black exhaust they belched as the rings wore. Throughout high school I took the Q41 bus to school and the NYC bus companies (Green Lines ran the Q41) all ran GMC's powered by 6v92's until the MTA took over. Many were repowered by Series 50's, a 4 banger version of the 12L 6 cylinder series 60, in order to improve air quality. It was not uncommon to a face full of thick diesel exhaust laiden with soot when waiting at the bus stop.
The Detroit Diesel 2 stroke series: 51, 53, 71, 92, 110, 149 have been around since 1939 when the company was started under GM. About 4 million of those engines were produced for various markets and parts will be available until 2040. Their weakness was oil ingress into the combustion chamber because of the scavenger ports at the lower portion of the cylinder which introduce air under pressure from a roots blower and sometimes boosted by a turbocharger. The action of the rings passing over the ports would allow some oil to make its way into the air stream and burned during combustion. And it got worse as the piston rings wore. If these guys solved the oil ingress problem then they have achieved what Detroit Diesel tried and failed to achieve for decades. That was one of the main problems with their design and that eventually led to them scrapping the 2 cycles as it was impossible to meet the emerging EPA emission standards. Perhaps there are some modern materials or designs that simply weren't available at the time when Detroit was working on them.
I remember one trucker saying something like "When I ran Detroit's I always kept spare oil, belts, oil, filters, oil, and more oil." They loved burning through it. Another issue was "slobbering"; it was not uncommon to see a trailer pulled by a detroit powered tractor with a big greasy soot streak near the exhaust stack opening. Some of the oil was partly combusted or escaped unburnt and made a mess. They also leak oil from everywhere. Though I will say this, I absolutely love the sound of them. I tried buying an old Mack WS Cruiseliner that was a former fire pumper which was 6v92 powered but the engine was blown and I didnt have the $2000+ to have it towed to NYC from down south. Wound up buying a B61 but that WS was my missed opportunity that I can't stop thinking about. Second picture, the red cab-chassis: https://www.trucksplanet.com/catalog/model.php?id=398 [trucksplanet.com] Sigh. Long frame and day cab with a detroit which is rare. I'd have added a 12k pusher axle, put a 20 ton hook lift on it with a flatbed body, and heavy pintle hitch on the rear. The paint job would be black out with HID headlamps and black out chrome accents. Strait pipe it and let the little 6v92T scream down the highway. Wound up buying a running B61. Anyway, I digress...