New engine shakes up auto industry(msnbc.msn.com)
msnbc.msn.com
New engine shakes up auto industry
http://www.msnbc.msn.com/id/42460541/ns/technology_and_science-innovation/
46 comments
> There's been alternative engine development for almost as long as there's been the combustion engine, and nothing yet has made an impact.
That's not actually true. There have been an enormous variety of "impacts" from alternative engine designs. It's just that the engines that made the biggest "impacts" aren't "alternative" any more.
External-combustion engine: prior to 70 AD (aeolipile).
Internal-combustion rocket engine: 1200s.
Steam turbine (impact-turbine steam-jack): Taqi al-Din, 1600s.
Piston-vacuum steam engine: Newcomen, 1712.
Separate-condenser vacuum steam engine: Watt, 1765.
High-pressure steam engine: early 1800s, although maybe we should assign the credit to Hornblower, 1785.
Stirling engine: Stirling, 1816.
Otto engine: Otto, 1861 (or maybe some Italians in the 1850s.)
Two-stroke engine: Clerk, 1881.
Atkinson-cycle engine: Atkinson, 1882.
Rotary engine: Millet, 1889.
Diesel engine: Diesel, 1892.
Progressive-expansion turbine: Parsons, 1897.
Four-stroke diesel engine: Diesel, 1897.
Combustion-gas turbine: Elling, 1903.
Pulsejet (used in buzz-bombs): Karavodin, 1907.
Monosoupape, used in the Sopwith Camel: 1913.
Liquid-fueled rocket: Goddard, 1926.
Turbojet: Whittle and von Ohain, 1930s.
Ramjet: Leduc, 1936.
Turbofan: 1943.
Wankel engine: Wankel, 1954.
I've omitted minor changes like turbochargers, nozzle shapes, fuel injection, continuous-jerk camshafts, and so on; even though they're very practically important, I don't think they represent "alternative combustion engines". I've also omitted designs that haven't seen widespread use.
Now, from this, it looks like nothing has happened for 50 years. That is an illusion. The Atkinson engine only became significant in the last decade or two; Wankel's device only became significant in the 1970s; the ramjet didn't become significant until the 1950s; steam turbines went from a curiosity in the 1600s to the prime mover for much of the world's economy today, but it wasn't until Parsons' redesign that they really mattered.
Over the last 50 years, many new heat engine designs have been created: nutating-disc engines, thermoacoustic engines, the quasiturbine, scramjets, Stelzer's engine, the fluidyne engine, Sarich's orbital engine, the IRIS engine, and now this "wave disc generator". It's too early to tell which, if any, of these will turn out to be useful in the long run — at least as useful as the Wankel engine was in Mazda’s cars.
That's not actually true. There have been an enormous variety of "impacts" from alternative engine designs. It's just that the engines that made the biggest "impacts" aren't "alternative" any more.
External-combustion engine: prior to 70 AD (aeolipile).
Internal-combustion rocket engine: 1200s.
Steam turbine (impact-turbine steam-jack): Taqi al-Din, 1600s.
Piston-vacuum steam engine: Newcomen, 1712.
Separate-condenser vacuum steam engine: Watt, 1765.
High-pressure steam engine: early 1800s, although maybe we should assign the credit to Hornblower, 1785.
Stirling engine: Stirling, 1816.
Otto engine: Otto, 1861 (or maybe some Italians in the 1850s.)
Two-stroke engine: Clerk, 1881.
Atkinson-cycle engine: Atkinson, 1882.
Rotary engine: Millet, 1889.
Diesel engine: Diesel, 1892.
Progressive-expansion turbine: Parsons, 1897.
Four-stroke diesel engine: Diesel, 1897.
Combustion-gas turbine: Elling, 1903.
Pulsejet (used in buzz-bombs): Karavodin, 1907.
Monosoupape, used in the Sopwith Camel: 1913.
Liquid-fueled rocket: Goddard, 1926.
Turbojet: Whittle and von Ohain, 1930s.
Ramjet: Leduc, 1936.
Turbofan: 1943.
Wankel engine: Wankel, 1954.
I've omitted minor changes like turbochargers, nozzle shapes, fuel injection, continuous-jerk camshafts, and so on; even though they're very practically important, I don't think they represent "alternative combustion engines". I've also omitted designs that haven't seen widespread use.
Now, from this, it looks like nothing has happened for 50 years. That is an illusion. The Atkinson engine only became significant in the last decade or two; Wankel's device only became significant in the 1970s; the ramjet didn't become significant until the 1950s; steam turbines went from a curiosity in the 1600s to the prime mover for much of the world's economy today, but it wasn't until Parsons' redesign that they really mattered.
Over the last 50 years, many new heat engine designs have been created: nutating-disc engines, thermoacoustic engines, the quasiturbine, scramjets, Stelzer's engine, the fluidyne engine, Sarich's orbital engine, the IRIS engine, and now this "wave disc generator". It's too early to tell which, if any, of these will turn out to be useful in the long run — at least as useful as the Wankel engine was in Mazda’s cars.
thanks. that's a great list btw.
I guess I was specifically referring to car engines which, aside from the Wankel, are the same basic idea (pistons turning a crankshaft) that's been around forever. Yes, the technology has improved out of sight, and there's been a number of significant innovations like you've mentioned, but I've never seen anything outside the piston/crankshaft paradigm take hold.
About 15 years ago I was able to tour the Orbital Engine workshops and have a look at their stuff and chat to their engineers. At the time (mid 90's) they had developed a two stroke car engine they had running in a bmw. The engine made more power and torque, used about 20% less fuel and was about 30% lighter than the one it replaced, yet nothing ever came of it. [0]
I'd love to see this stuff happen, but I think the problem lies not with the technologies but rather that manufacturers are too conservative
[0] bloody hell, I've found one of the cars and it's on the market at the moment http://www.carsales.com.au/all-cars/private/details.aspx?seo...
I guess I was specifically referring to car engines which, aside from the Wankel, are the same basic idea (pistons turning a crankshaft) that's been around forever. Yes, the technology has improved out of sight, and there's been a number of significant innovations like you've mentioned, but I've never seen anything outside the piston/crankshaft paradigm take hold.
About 15 years ago I was able to tour the Orbital Engine workshops and have a look at their stuff and chat to their engineers. At the time (mid 90's) they had developed a two stroke car engine they had running in a bmw. The engine made more power and torque, used about 20% less fuel and was about 30% lighter than the one it replaced, yet nothing ever came of it. [0]
I'd love to see this stuff happen, but I think the problem lies not with the technologies but rather that manufacturers are too conservative
[0] bloody hell, I've found one of the cars and it's on the market at the moment http://www.carsales.com.au/all-cars/private/details.aspx?seo...
> I guess I was specifically referring to car engines which, aside from the Wankel, are the same basic idea
Well, there have been a few commercially available cars driven by rotary engines (which are pistons being turned by a crankshaft, rather than turning a crankshaft) and cars driven by steam engines, but you're right that at the moment, only Otto-cylinder, Diesel, Atkinson, and Otto Wankel engines are on the market for cars, and all of these except for the Wankel are built around pistons turning a crankshaft.
But if you're talking about innovations on the level of more-efficient two-stroke engines, rather than totally new engine designs, I think you can find a lot of those that have made it to mass production in the last few decades. Atkinson-electric hybrids might be the biggest one, but there's electronic ignition control, gasoline direct injection, electronic fuel injection, coaxial springs to prevent valve dwell, continuous-jerk cams, hydraulic tappets, variable valve timing, etc.
That list certainly supports your contention that manufacturers are too conservative, though.
(I don't really know much about this stuff, so let me know if I'm making some kind of goofy mistake.)
It seems to me that in order to make manufacturers less conservative, we need to have more of them. Widespread CAD and simulation facilities and automated fabrication that lowers the cost of producing prototypes could make a big difference.
BTW, the SyTech is another experimental non-crankshaft design: http://www.autospeed.com/cms/A_0948/article.html
Well, there have been a few commercially available cars driven by rotary engines (which are pistons being turned by a crankshaft, rather than turning a crankshaft) and cars driven by steam engines, but you're right that at the moment, only Otto-cylinder, Diesel, Atkinson, and Otto Wankel engines are on the market for cars, and all of these except for the Wankel are built around pistons turning a crankshaft.
But if you're talking about innovations on the level of more-efficient two-stroke engines, rather than totally new engine designs, I think you can find a lot of those that have made it to mass production in the last few decades. Atkinson-electric hybrids might be the biggest one, but there's electronic ignition control, gasoline direct injection, electronic fuel injection, coaxial springs to prevent valve dwell, continuous-jerk cams, hydraulic tappets, variable valve timing, etc.
That list certainly supports your contention that manufacturers are too conservative, though.
(I don't really know much about this stuff, so let me know if I'm making some kind of goofy mistake.)
It seems to me that in order to make manufacturers less conservative, we need to have more of them. Widespread CAD and simulation facilities and automated fabrication that lowers the cost of producing prototypes could make a big difference.
BTW, the SyTech is another experimental non-crankshaft design: http://www.autospeed.com/cms/A_0948/article.html
It's not easy to change from one engine to another radically different type. I would love for them to go down a path of better fuel economy, torque, weight, and horsepower. But you are looking at manufacturers trying to sell cars that need to be serviced down the line. service centers are not trained to handle X technology and the only place you could get it serviced would be the dealership. As a consumer I probably would not want to take the risk of an unknown longevity engine with unknown costs to fix it so I can save 20% on fuel; the engine design must be > 50%-75% less fuel(or some other reason that would make it a no brainer) used to make it worth taking a gamble on unknown quantities.
The situation today is different. This engine is supposed to optimize hybrid cars (it is supposed to generate electricity to drive an electric motor) and hybrids are something new, they haven't existed for more than a century, which means that there is likely more untapped potential for optimization. This engine wouldn't be practical in a standard gasoline car and it's not designed to be used in one.
It obviously can still fail but I don't think it's possible to draw historical parallels.
It obviously can still fail but I don't think it's possible to draw historical parallels.
Well if we're talking about that, then reciprocating engines can do pretty well (the prius engine is over 33% efficient when running in the ideal range, and it actually exists today; diesels do even better)
But maybe an electric car needs a gasoline engine as much as a tablet computer needs a keyboard, and maybe we're several years away from seeing that in the electric car case, just as the belief that a tablet didn't need a keyboard didn't become widespread until the iPad.
That's exactly what I was thinking. Any Mazda fan will tell you that automobile engines don't need pistons.
Michigan State's team of engineers hope to have a car-sized 25-kilowatt version of the prototype ready by the end of the year.
It should be noted than 25kW is 33HP. Though it's possible to make a useful car with that little power, 33HP is generally considered an appropriate power level for a beginner's motorcycle, not a car. Even if it's much lighter than a piston engine and has such a wide powerband that it doesn't need a gearbox, it's likely they'd need a lot more power for consumer acceptance even in small cars.
Edit: I googled this and found that the intent is to use this engine to run generators to charge batteries in hybrid cars, not for direct propulsion. In that case, the cars probably won't be much, if any lighter than standard cars since all the weight savings will be replaced with batteries. Power output could, of course be lower than a standard car engine and still provide good performance since the electric motors could have peak outputs far exceeding the sustained output of the generator.
It should be noted than 25kW is 33HP. Though it's possible to make a useful car with that little power, 33HP is generally considered an appropriate power level for a beginner's motorcycle, not a car. Even if it's much lighter than a piston engine and has such a wide powerband that it doesn't need a gearbox, it's likely they'd need a lot more power for consumer acceptance even in small cars.
Edit: I googled this and found that the intent is to use this engine to run generators to charge batteries in hybrid cars, not for direct propulsion. In that case, the cars probably won't be much, if any lighter than standard cars since all the weight savings will be replaced with batteries. Power output could, of course be lower than a standard car engine and still provide good performance since the electric motors could have peak outputs far exceeding the sustained output of the generator.
33HP in an electric vehicle is actually not as bad as it sounds. Most of the horsepower needed in a vehicle is to overcome inertia (e.g. starting from a standing stop) and electric motors can output full power at 0 RPM unlike an internal combustion engine. So a car driven by an electric motor would not need a clutch or transmission, which eliminates a significant inefficiency in the drivetrain.
Internal combustion engines and electric motors are also not rated in the same way. Electric motor HP is "rated" horsepower (what it can produce continuously without overheating; generally it's capable of more for short periods) while internal combustion horsepower tends to be "maximum" horsepower and there are a lot of different ways to come up with a number, some purely based on calculations and some on actual measurement. So unfortunately HP is not an apples-to-apples number between electric and combustion engines.
Internal combustion engines and electric motors are also not rated in the same way. Electric motor HP is "rated" horsepower (what it can produce continuously without overheating; generally it's capable of more for short periods) while internal combustion horsepower tends to be "maximum" horsepower and there are a lot of different ways to come up with a number, some purely based on calculations and some on actual measurement. So unfortunately HP is not an apples-to-apples number between electric and combustion engines.
If you live anywhere with mountains, it's exactly as bad as it sounds though.
Yes. However lets consider this: If it meets 80% of the population's 100% needs then its good enough for me. Imagine a ~60% or so reduction in co2 emissions world wide. Sure 20% of people still need their big trucks, but at least not everyone. Not to mention shaving 1000 pounds off the weight of the car not only gives fuel gains, but lowers power requirements to move that vehicle. Now I was going to say... take that, combine it with tesla's engine, and now you have potentially a long-range vehicle, a vehicle that can already do 300 miles on a charge and potentially a gas engine that can charge it up so you get a nice and unlimited mileage as long as you refuel.
Not to mention cheaper cars!!!!!
Not to mention cheaper cars!!!!!
shaving 1000 pounds off the weight of the car...
It is not likely that a hybrid car with no direct propulsion from the combustion engine will be 1000 pounds lighter than a comparable conventional car, even if its combustion engine weighs next to nothing. Batteries are heavy, and this type of hybrid needs more of them than the more common type that uses electric to augment the power of a combustion engine.
I'm not saying this won't be an improvement. I'm just saying some of the claims seem a little extravagant.
It is not likely that a hybrid car with no direct propulsion from the combustion engine will be 1000 pounds lighter than a comparable conventional car, even if its combustion engine weighs next to nothing. Batteries are heavy, and this type of hybrid needs more of them than the more common type that uses electric to augment the power of a combustion engine.
I'm not saying this won't be an improvement. I'm just saying some of the claims seem a little extravagant.
Even if you discount the batteries entirely, 1000 lbs seems a bit high for the weight of an engine (or even engine and transmission). I suppose maybe a big block V8 with a very strong Ford pickup transmission could weight that much; but it would be more fair to use a figure for the weight of an I4 engine with front wheel drive transaxle, which would probably closer to 600 lbs than 1000.
I don't think you're giving it quite enough credit. For a hybrid car what you can do is marry this to a more powerful electric motor (say, 40HP). When the car is cruising at a constant speed it's running on the engine and charging the batteries (or using just the batteries with the motor off). When the car is accelerating a lot it's using the batteries/motor and the engine at the same time (generating say 70HP or more). Given the lower weight and higher efficiency of this engine that's pretty significant. If it's possible to create a hybrid drive-train (including batteries) that weighs only as much or only a little more than a pure gasoline drive-train that could translate into much cheaper hybrid vehicles on the market.
P.S. For clarity's sake, modern hybrids are enormous compromises due to the weight of the battery and electric motor. For a hybrid you want the highest efficiency possible and thus the lowest total vehicle weight you can manage without compromise safety. The necessity of heavy batteries fights in the opposite direction, so in order to produce a fuel efficient vehicle car makers use more expensive, lighter weight materials in the construction of the vehicle. This increases the complexity of manufacturing (more different materials are being used) and raises the price of the vehicle. If you could drop in a drive-train which kept the weight the same that would change the industry dramatically.
P.S. For clarity's sake, modern hybrids are enormous compromises due to the weight of the battery and electric motor. For a hybrid you want the highest efficiency possible and thus the lowest total vehicle weight you can manage without compromise safety. The necessity of heavy batteries fights in the opposite direction, so in order to produce a fuel efficient vehicle car makers use more expensive, lighter weight materials in the construction of the vehicle. This increases the complexity of manufacturing (more different materials are being used) and raises the price of the vehicle. If you could drop in a drive-train which kept the weight the same that would change the industry dramatically.
Further research in to this engine design suggests it has a very narrow efficient range and the intended application is as a generator only, not to directly power the wheels. The electric motor would have to provide all the power required to propel the car. Of course, pure electric cars have already been done with some success, and a hybrid based on this system could have electric motors with a lot more than 33, 40 or 70 hp.
That's modern power creep speaking. You don't need the massive power of modern automobiles. That 7 second 0-60 on your mid-sized sedan? Faster than nearly all sports cars 30 years ago. Absolutely blistering compared to any car 50 years ago.
40hp is about what you use on the freeway, or at least it used to be before the average car came to weight 2 tons. You don't need a whole lot more than that. Hell, the MG Midget was offered with a 30HP engine once, IIRC.
I'm quite sure in a decade or two we're going to have people saying things like, "It's true you CAN make a car with only 200hp, but it's generally accepted you need at least 800hp for any car"...
40hp is about what you use on the freeway, or at least it used to be before the average car came to weight 2 tons. You don't need a whole lot more than that. Hell, the MG Midget was offered with a 30HP engine once, IIRC.
I'm quite sure in a decade or two we're going to have people saying things like, "It's true you CAN make a car with only 200hp, but it's generally accepted you need at least 800hp for any car"...
I had an air-cooled Vanagon for a while. It was 2½ tons, due to aftermarket camper modifications, and could manage a bit over 60mph on its 70-horsepower 2-liter air-cooled engine, despite having the aerodynamics of a brick. Something with half the frontal surface area or half the drag coefficient, such as basically any modern vehicle, could manage quite well with half that horsepower.
I think the average US car weighed a lot more in the 1960s than in the 1970s, 1980s, or 1990s. Maybe widespread SUV use is pushing that average back up.
Did the http://en.wikipedia.org/wiki/Deux_Chevaux really have only two horsepower?
I think the average US car weighed a lot more in the 1960s than in the 1970s, 1980s, or 1990s. Maybe widespread SUV use is pushing that average back up.
Did the http://en.wikipedia.org/wiki/Deux_Chevaux really have only two horsepower?
Reading the content of the article you linked, the first version had 9hp and was "notoriously underpowered". Most 2CVs actually came with engines around 30 HP. This car also weighed only 560kg, which is lighter than even a Smart Fortwo. Modern crash safety standards mean it's effectively impossible[0] to produce street legal cars that weigh less.
The fact that a car was once successfully sold in Europe with such a low power to weight ratio doesn't mean it would succeed in today's market. Consumer expectations have changed. They could change again, but there would have to be a good reason.
[0] Lighter cars could be made from more exotic materials, but those would drive the price out of reach of the average buyer.
The fact that a car was once successfully sold in Europe with such a low power to weight ratio doesn't mean it would succeed in today's market. Consumer expectations have changed. They could change again, but there would have to be a good reason.
[0] Lighter cars could be made from more exotic materials, but those would drive the price out of reach of the average buyer.
> I'm quite sure in a decade or two
I can't wait, thanks for the cheery prediction!
I can't wait, thanks for the cheery prediction!
The engine used in the original VW Beetle was about 40 HP (started out even less, and later models were 60 HP, but for many years it was 40). I have heard that it only takes about 18 HP to overcome air resistance at highway speeds for a small car.
Also, it's important to note the reason for the big discrepancy between the "inflated" horsepower ratings modern cars have vs. the lower HP in older classic cars: power is RPM * torque, and gas engines are rated in peak horsepower. To reach the advertised peak horsepower of modern engines, you have to be fairly high RPM (5K to 6K) whereas an older, lower horsepower rated engine might start to drop off its power curve after 4K. But at lower RPM the torques may be similar, or even higher for some older engines (the VW engine in particular with its Boxer configuration was optimized to have good torque for its size). What this means is that unless you are driving full throttle all the time at high RPM, you're not necessarily pushing all 100+ horsepower or whatever that your modern engine is capable of in theory, and so conversely an engine with smaller max horsepower is not as much worse as you'd think it would be.
Also, it's important to note the reason for the big discrepancy between the "inflated" horsepower ratings modern cars have vs. the lower HP in older classic cars: power is RPM * torque, and gas engines are rated in peak horsepower. To reach the advertised peak horsepower of modern engines, you have to be fairly high RPM (5K to 6K) whereas an older, lower horsepower rated engine might start to drop off its power curve after 4K. But at lower RPM the torques may be similar, or even higher for some older engines (the VW engine in particular with its Boxer configuration was optimized to have good torque for its size). What this means is that unless you are driving full throttle all the time at high RPM, you're not necessarily pushing all 100+ horsepower or whatever that your modern engine is capable of in theory, and so conversely an engine with smaller max horsepower is not as much worse as you'd think it would be.
> It should be noted than 25kW is 33HP. Though it's possible to make a useful car with that little power ...
Not only it's possible, but many successful european cars hadn't more : Citröen 2CV, Renault 4CV, Fiat 500 and 600, and most other economy cars of the 50s and 60s hadn't even that power, and sold by the millions.
Not only it's possible, but many successful european cars hadn't more : Citröen 2CV, Renault 4CV, Fiat 500 and 600, and most other economy cars of the 50s and 60s hadn't even that power, and sold by the millions.
Geeks? Smart guy/gals?
I couldn't tell you if the thing is real or not.
But, if such an engine, with two-three times(!!!) the efficiency of a standard gasoline engine with a lower power to weight ratio, were to be producible at 25kW, all the (hypothetical underpowering) problems could be solved by ...
... using ...
TWO engines!! (or three engines)
... jeesh ...
It's for hybrids. Each engine would just charge a battery.
I couldn't tell you if the thing is real or not.
But, if such an engine, with two-three times(!!!) the efficiency of a standard gasoline engine with a lower power to weight ratio, were to be producible at 25kW, all the (hypothetical underpowering) problems could be solved by ...
... using ...
TWO engines!! (or three engines)
... jeesh ...
It's for hybrids. Each engine would just charge a battery.
My first car, and one that I'm still very fond of, had 29HP [0]. I'm 31, so I'm not talking with a 'get off my lawn' 'glorify the past' attitude. In fact, I liked the car that much, that I had several of those in my life.
Oh - yeah: I drove a hell of a lot on the German Autobahn with it as well. Fast? Hell no. But I still have that speeding ticket (went just a tiny bit faster than 100km/h) somewhere as a nice souvenir.
0: https://secure.wikimedia.org/wikipedia/en/wiki/Citro%C3%ABn_...
Oh - yeah: I drove a hell of a lot on the German Autobahn with it as well. Fast? Hell no. But I still have that speeding ticket (went just a tiny bit faster than 100km/h) somewhere as a nice souvenir.
0: https://secure.wikimedia.org/wikipedia/en/wiki/Citro%C3%ABn_...
It should be noted than 25kW is 33HP.
But the design obviously isn't limited to this? A bigger engine could give more power yet still consume less than a regular piston engine. Or 1-2 of these running in parallel, depending on the load.
But the design obviously isn't limited to this? A bigger engine could give more power yet still consume less than a regular piston engine. Or 1-2 of these running in parallel, depending on the load.
"Michigan State's team of engineers hope to have a car-sized 25-kilowatt version of the prototype ready by the end of the year."
I'll pay attention once this happens. As they say, there's many a slip between the cup and the lip. Lab projections invariably end up being over-optimistic.
I'll pay attention once this happens. As they say, there's many a slip between the cup and the lip. Lab projections invariably end up being over-optimistic.
Yeah. Would it have killed 'em to at least build a working prototype before sending out the press release?
Even if the claims they're making do turn out to be true, it could still suck in any number of other ways. How durable is this engine? Is it still gonna be running after a hundred thousand miles?
Even if the claims they're making do turn out to be true, it could still suck in any number of other ways. How durable is this engine? Is it still gonna be running after a hundred thousand miles?
"Last week, the prototype was presented to the energy division of the Advanced Research Projects Agency, which is backing the Michigan State University Engine Research Laboratory with $2.5 million in funding."
I am just as skeptical, but if this is how they get their funding to build that working prototype than I'd say it's fair enough.
I am just as skeptical, but if this is how they get their funding to build that working prototype than I'd say it's fair enough.
Even more importantly, how easy is it to maintain this engine? The reason rotary engines haven't become more mainstream is that the first attempt (the Mazda RX-7) was notoriously difficult to repair. The RX-8 is better (I hear), but the damage has been done - of all the major carmakers out there, only Mazda offers a rotary engine.
Untrue.
The RX-7's rotary engine (the 13B series) is actually phenomenally reliable, and there are many examples with well over 300k road miles. The RX-8 uses a newer variant of the same engine - the 13B-MSP RENESIS. Additionally, Mazda used the rotary in competition (in the infamous Mazda 787B) at the 24 hours of LeMans, which is a notoriously difficult test of engine reliability.
The myth of poor rotary reliability primarily stems from the 3rd-generation RX-7. The notoriously-complex mechanically-controlled sequential twin-turbo system (affectionately known as "the rat nest") was prone to hose disconnects and failures, which often led to over-boost situations. Additionally, owners that modify their cars often exacerbated the problem, installing free-flowing intakes and exhausts, as well as boost controllers, and did not properly modify air-fuel ratios to compensate. These situations led to increased engine heat and premature failure, which gave the rotary an unfair bad reputation. Many owners now convert to a simpler single-turbo setup with electronic boost control and careful air-fuel tuning, which is far more reliable.
The actual (and admittedly significant) drawbacks of rotary engines are poor fuel efficiency and high exhaust emissions, both due to incomplete combustion. This has kept them out of mainstream applications and thus they tend to be used primarily in performance applications.
The RX-7's rotary engine (the 13B series) is actually phenomenally reliable, and there are many examples with well over 300k road miles. The RX-8 uses a newer variant of the same engine - the 13B-MSP RENESIS. Additionally, Mazda used the rotary in competition (in the infamous Mazda 787B) at the 24 hours of LeMans, which is a notoriously difficult test of engine reliability.
The myth of poor rotary reliability primarily stems from the 3rd-generation RX-7. The notoriously-complex mechanically-controlled sequential twin-turbo system (affectionately known as "the rat nest") was prone to hose disconnects and failures, which often led to over-boost situations. Additionally, owners that modify their cars often exacerbated the problem, installing free-flowing intakes and exhausts, as well as boost controllers, and did not properly modify air-fuel ratios to compensate. These situations led to increased engine heat and premature failure, which gave the rotary an unfair bad reputation. Many owners now convert to a simpler single-turbo setup with electronic boost control and careful air-fuel tuning, which is far more reliable.
The actual (and admittedly significant) drawbacks of rotary engines are poor fuel efficiency and high exhaust emissions, both due to incomplete combustion. This has kept them out of mainstream applications and thus they tend to be used primarily in performance applications.
The states complaint was difficulty of repair, not unreliability.
This is also untrue; the rotary is much simpler than a piston engine and has far fewer moving parts. Replacing major mechanical components on a rotary is easier than a reciprocating engine. As long as the associated systems are also simple, the rotary is one of the easiest engines there is to repair.
Most work that has to be done on car engines has nothing to do with the engine itself, but control, ignition and fuel delivery systems. Older rotaries had carburetors, which required regular adjustments to keep in tune. As mentioned above, the third-generation RX-7 had a complicated twin-turbo system that created some reliability problems of its own. Non-turbocharged fuel-injected second-generation RX-7s on the other hand are some of the most reliable and low-maintenance sports cars ever produced.
This is also untrue; the rotary is much simpler than a piston engine and has far fewer moving parts. Replacing major mechanical components on a rotary is easier than a reciprocating engine. As long as the associated systems are also simple, the rotary is one of the easiest engines there is to repair.
Most work that has to be done on car engines has nothing to do with the engine itself, but control, ignition and fuel delivery systems. Older rotaries had carburetors, which required regular adjustments to keep in tune. As mentioned above, the third-generation RX-7 had a complicated twin-turbo system that created some reliability problems of its own. Non-turbocharged fuel-injected second-generation RX-7s on the other hand are some of the most reliable and low-maintenance sports cars ever produced.
After looking into it more, it seems that a lot of the initial complaints about difficulty of repair were due to the lack of spare parts. It seems that Mazda had some manufacturing difficulties with the early versions of the RX7 engines and couldn't manage to meet demand for both whole engines and spare parts.
Also because they tend to light on fire, have next to no torque where you want it, purposefully burn a metered amount of oil, get crap mileage (which degrades relatively quickly to boot), ...
Eventually people tire of playing the rotary game, usually when they realize the weight savings and high redline aren't worth the numerous flaws on anything but a track car (and even then, only if you can live without much low-end torque).
Eventually people tire of playing the rotary game, usually when they realize the weight savings and high redline aren't worth the numerous flaws on anything but a track car (and even then, only if you can live without much low-end torque).
There is nothing in this story and video to back up any of the claims they are making. He just waves around a rotating disc.
He could be talking about cold fusion in just the same way ;)
[edit] looking at the duplicate link, they refer to their own article from 2006. Cold fusion would either have been laughed away or taken over the world. Same thing here I would assume. [/edit]
He could be talking about cold fusion in just the same way ;)
[edit] looking at the duplicate link, they refer to their own article from 2006. Cold fusion would either have been laughed away or taken over the world. Same thing here I would assume. [/edit]
They should seriously open source this design before the oil industry spooks show up and make it go away.
Oil industry should be happy about this... it's still burning petrol, after all. Many other ideas on the drawing board are trying to take petrol out of the equation.
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http://www.aptera.com Prototype by the end of the year? I swear Aptera has been saying that for the last few... (Okay, they have prototypes but they're not on the market yet.)
This sounds a lot like a rotary engine with multiple combustion chambers. The idea of sliding seals should be enough to have any rotary afficionado denounce this new engine.
there is a lot of ingenious engines. The question is which one can be made into practically usable product.
There is even productized version of rotary-vane engine coming supposedly next year in a Russian car:
http://www.fastcompany.com/1709400/russian-billionaire-unlea...
I'd be though very surprised if they pull it off as beside Mazda rotary i don't know other mass-produced cars with non-traditional engines.
There is even productized version of rotary-vane engine coming supposedly next year in a Russian car:
http://www.fastcompany.com/1709400/russian-billionaire-unlea...
I'd be though very surprised if they pull it off as beside Mazda rotary i don't know other mass-produced cars with non-traditional engines.
Ralph Sarich invented the orbital engine [0] almost 40 years ago, formed a company and spent millions on the idea but it went nowhere. Interestingly, they knew when to change direction and ended up making a number of breakthroughs in the field of two stroke engines. The company is still in business today [1]
[0] http://en.wikipedia.org/wiki/Orbital_engine
[1] http://www.orbeng.com.au/