Mazda to revive rotary engine as EV range extender https://www.mazda-press.com/eu/news/...nge-extender-/ To be honest, if the resulting car is RWD, I'm sold even with the infrastructure needs for home charging. Quote:
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makes no sense... if you wanted an IC engine for a range extender, why would you pick a gas guzzling rotary instead of your skyactive lineup which has amazing fuel efficiency. Yeah rotaries are cool, but not in this application. |
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Ironically, it negates the purpose, like you said. Sent from my Pixel XL using Tapatalk |
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The idea has been around for a while, but I haven't seen any technical data yet, so I still have doubts. Quote:
Ever looked at a 13B and wonder, "Wow, that tiny thing makes 200+ BHP?!" It actually works out to be about 1 cubic foot in physical volume. Now imagine a generator that will supposedly have about 1/4 of the displacement of the 13B. It can be very beneficial to packaging. People call it a "shoebox" for a reason. And if you drive a rotary car, you will definitely notice the fact it's silky smooth, to the point that RX-7 and RX-8 both have a redline beeper from the factory. This is very beneficial for the comfort. Fuel consumption is not a huge deal. Sure, a rotary is less efficient than a piston engine, but like CorneringArtist mentioned, it's running at a constant load as a generator only, which means it will still sip fuel rather than chug it like my RX-8. Design the exhaust for that specific RPM the generator runs at and you will barely even notice it running. The only real concern I have is how rotary burns oil by design. Burning 4-stroke is easier for maintenance but harder for emissions, while 2-stroke burns cleaner, but requires more attention. |
They've already tested the rotary generator in the Mazda2 in 2013. It was a single rotor 300CC unit and reached about 400km combined range. Full electric was 200km. I'm guessing if they can minimise oil consumption or even have a feed system to maintain oil levels, it might solve that problem. |
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I think you are down playing how inefficient these engines were. An Evo for example made 70hp and 150 torque more (yes double the torque), was much heavier, had AWD, and yet was able to still be more fuel efficient than an RX8. ANNND Evos were known to be one of the worst fuel guzzlers of the day when compared to any other car like a 135i that was able to produce even more power and use much less fuel. I can't see a rotary ever making a return, especially with all the advancements in the piston engine. Even as just a range extender, its automatically a less efficient platform which defeats the whole purpose. |
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This actually makes me wonder if they will implement some designs from the 16X concept, namely the flatter rotor, direct injection, and all-aluminum construction(old 13Bs all come with aluminum housings and cast iron plates). Quote:
I realize that a rotary is not as efficient as a piston engine, I stated that, and Mazda realizes it as well. But what if you compare this new 300cc rotary range extender to a piston engine that can generate the same amount of power at a constant load? You just have a set RPM you can optimize everything(air flow, fuel injection, etc.) for and that can certainly have some interesting results. One optimization I can think right off my head: I know that a stock RX-8 ECU will have the AFR in the range of 10 when you floor it, and in general, it runs pig rich to, ironically, help the catalytic converter. There is no need for that in a range extender. You can always just target close to the 14.7 stoich AFR and adjust a tiny bit for the NOx emission. All that said, I am not delusional. There are definitely problems and that's why I am not overly optimistic about it. Last time I checked, Mazda only has about 20 people working on the rotary engine, so I am not that hopeful. The Renesis in RX-8 was already on the back bench when it was in development and look what happened. This will also give the marketing department a run for its money given rotary's track record of non-reliability. |
man mazda dumped so much money and time into that rotary since buying the patent they just can't let it go lol. but i still got love. got bit by the rotary bug myself once upon a time. took one look at the animated video and said this is just fucking retarded... i gotta get one! had an s4t2 and s5na street ported. haven't looked much into this thing but i'm curious how it'll meet emissions standards. always a problem with rotaries since there's no dwell. that and, as mentioned, the lubrication |
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And yeah, I think all car people know it's a dumb idea in many ways, but everyone still loves it when they see one. As for emission, I wonder if Mazda has figured out that sweet spot for the amount of oil to inject to keep the seals lubricated while keeping the emissions low. Again, it's a compromise between 4-stroke oil and 2-stroke oil. If they make the oil pan big enough and go with the same 4-stroke oil injection that has been used historically, the engine can potentially not need any oil added between oil changes. Actually, my RX-8's oil injection is electronically controlled and it doesn't consume much oil on highway trips(constant RPM and load). It's true that the timing is static on a rotary engine. No valves in a rotary engine mean fewer moving parts and high revs, but the timing cannot be optimized for all RPM, unfortunately. However, since this generator runs at a set load and RPM, this will also become a non-issue. Figure out the best intake and exhaust port positions for that set RPM and you are good to go. |
few thoughts I am continually blown away that a relatively small manufacturer can continue to push the envelope...Skyactiv-X squeezing out another 25% on top of the ultra-high compression the 2012 Skyactiv-G this rotary-range extender in the article has already been tested since 2013 https://o.aolcdn.com/images/dims3/GL...e-extender.jpg Quote:
Also, do you still need to warm up a Rotary for longevity sake? the hassle and durability of a rotary probably means I would not want one in a daily |
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actually when i said dwell i was referring to piston dwell time. Which promotes a fuller burn and higher thermal efficiency. There's no dwell in a rotary since the rotor is constantly spinning. During combustion, the charge mixture at the trailing side of the rotor is pretty much thrown out the tailpipe. Hence the trailing plug. But it doesn't help much. One of the reasons for the multiple cats and high hc. Maybe they'll implement hcci. That would probably remedy it. Or maybe laser ignition. |
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And yes, RX-8 gas mileage is pretty bad, but again, as it has to drive the wheels, the load will constantly change as you accelerate the car. The highway mileage also suffers because of the short gears and thus more pumping losses. My RX-8 will rev at 3k RPM at 92 km/h in 6th(last) gear. It's to the point that some RX-7 owners claim that they get better gas mileage on highways. Also, remember that these are sports cars - performance will be a bigger concern than fuel economy. As for warm-up, that has always been a myth in ANY modern car. The "idle until warm" should have died with carburetors. The only time I would do that is if my windshield is covered in ice and I can't safely drive until everything is warmed up. Otherwise, I idle for 15 seconds after a cold start and off I go. Any engine shouldn't be driven hard when cold, piston or rotary. And one last thing to clear up since we are here: flooding. I have never flooded my 8. I stalled my car while cold twice, and both times it fired right back up. If an RX-8 floods, something is wrong. Either your ignition systems are dying, your battery is taking a dump or your engine has low compression. Quote:
The RX-8 side exhaust port gets rid of the port overlapping and makes it so that there is a greater chance that some unburnt gas will be burned in the next cycle. I think Mazda will be sticking to the side exhaust ports. HCCI could be a solution, but wouldn't that require a higher compression ratio? A Wankel rotary engine is only capable of 11:1 or so by design. That's why Rolls Royce's concept diesel Wankel had two rotors - a big rotor as a compressor and a small rotor as the actual engine. As for laser... Just the cost alone will mean it won't be in an econo car. And is it even in use in any road vehicles, anyway? Quote:
True, and in an RX-8 that's driven genetally, it wouldn't burn much oil. Again, the constant load and RPM means they can optimize everything for that particular condition. |
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