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AUTO • Rotary Combustion Wankel Engine
Article on WIKI ( 38 languages) ► goo.gl/tdcdp
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The Wankel cycle. The "A" marks one of the three apexes of the rotor. The "B" marks the eccentric shaft and the white portion is the lobe of the eccentric shaft. The shaft turns three times for each rotation of the rotor around the lobe and once for each orbital revolution around the eccentric shaft.
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52 comments
 
Now a nice graphic on how to mop up oil leaks might be apropos...
 
can any one tell me wht it is ???
 
+Telmo Figueiredo Filho You might be right these days - they historically struggled to get fuel economy to match normal reciprocating engines though.
 
I love these engines. They are lighter, have fewer components, and sound so crazy when pushed. And since there's no crack shaft, connecting rods, and other things, it would be more reliable? That is if you could keep yourself from roasting it.
 
interesting engine. Innovation is nifty.....they should take this one to the next level..
Wayne C
 
+Lauchlin MacGregor they have done. Its been in a variety of applications from cars to planes since the 50s
 
Oooh! I first saw the design a few years ago... It was presented by a Japanese mathematician who hosts a educational kiddie show... Forgot his full name but my professor referred to him as Aki... XD
 
I'm not so sure on that reliability +David House. These engines used to wear out their tips very quickly when used in British road cars in the 60s & 70s, requiring the engine to be rebuilt every 6,000 miles.

Mazda has used the engine in sportscar racing, but not had much luck with reliability.
 
Mazda used to put them in the RX-7 series cars in the late 70s. I even remember the advertising campaign. I always kind of wondered what happened to the development of these cars.
 
^ and now they use them in the RX-8. the fuel economy is not that great but overall it's a good design.
 
It was my impression that the Mazda RX-8 uses a rotary engine as well, albeit a slightly tweaked one. One of the rumored advantages to a rotary engine is a lack of a "redline" so to speak.
 
Their big claim to fame was the amount of power vs the displacement of the engine. They also make an amazingly wicked sound when wot at the higher rpms. Their design though brought about issues of high stress to very particular points which affected reliability and the point that it eats oil by design means you have to do something most americans don't do, watch your oil levels.
 
+William Dingle you're right, for some reason I got it in my head that they abandoned the thing completely. Now I want one. Grin Okay maybe not.
 
+Norris Washington A couple of my friends have RX-8s, and they're pretty good to be fair. My comment about fuel economy up there ^^ is based largely on their experiences. They struggle to get much above 20 mpg.
 
+Steve Mayne I actually think that it looks like a great car. It's not consistent with my existing life. I always kind of liked Mazda.
 
+James Field right you are. You would think that fewer moving parts would equate to fewer problems, but I guess the big problem would be where the apex meets the wall. Then again, what do I know...
 
Mazdas are a blast to drive, the handling is epic! i drive an '08 mazdaspeed3 and still grin from ear to ear every time i get in it. zoom zoom.
 
I used to own a Mazda 626GT. I loved that car. It was a blast to drive.
 
I should preface this comment by saying I'm by no means mechanically inclined; I have learned more about engines and how they work by the gifs you've posted than from any other source in my life. Thanks :)
 
I have watched this before really very very awesome demonstration.
 
The best thing is the name...Wankel, WANKEL, Wankel...
 
The thing I can't quite get a handle on is the force vector on the rotor. The exploding fuel/air mixture is going to exert forces when it expands, and I just don't know if its as efficient in this configuration than in a traditional otto piston/cylinder arrangement. Maybe that accounts for the lesser fuel economy ? also - how would one do direct fuel injection in this arrangement ?
 
They discontinued the mazda's rx lineup as far as im concerned right? Witch where the only cars that i know of that had rotative motors.
I've read that rotative has good power/weight relation... but fuel consumption and maintenance are a pain in the a**
 
I think the fuel combustion as well as emissions would be a tough problem. They already have two spark plugs in the combustion phase to try and completely burn all the fuel. The inertia of the rotor moving away from the combusting fuel/air probably causes lots fuel to go unburned at high RPM. They might be able to compensate with direct injection and reducing the amount of fuel delivered with the volume of air at higher RPMs, but then it may start to produce less power. Its probably also a problem in otto cycle engines, but I think it may be less because of the shape of the cylinder and the fact that the piston is moving towards the combustion chamber in the compression stroke and not away from it. I'm just spitballin' though..
 
My first car was a 1987 RX-7 GXL. Love this thing. Maintenance was tough, but I'd buy another one as a toy someday. I'm sure if they put more R&D into this concept they'd get over it's flaws.
 
Two wheelers (motorcycles) are the primary way the developing world drives.. They are cheap (starting $800) and have very good fuel efficiency (250 mpg claimed and around 150 on road).

The mileage has tripled in the last half century owing to continuous improvement by manufacturers. I always think, can the mileage be doubled in the future, say to 500 mpg? One way to do that is to have hybrid motorcycles... owing to regenerative braking and constant engine speed. But the engine weight and size needs to be small to compensate for the additional weight of batter and motors

A hybrid motorcycle with Wankel Engine can be a good solution. The power to weight ratio is good and efficiency is also comparable.
 
+Colin Toal they easily pull 250 HP out of a 1.3L engine andit does 0-60 in 5.9 secs. Hope that helps :)
 
+Nicolai Imset But displacement is not an apples to apples comparison here right ? How much fuel does that 1.3L engine burn @rpms producing 250HP ?

A better measure of efficiency would be joules of output per joule of input energy. Not volume of air in the engine at rest.
 
Uuuuhhh... This post just turned mega technichy!! Joules... O.o ... nice!
 
+Colin Toal They are usually compared to 2,5-3.0 litre piston engines. Not really sure about fuel consumption but it did improve vastly in the last two or three generations of engine. Worth to notice that Mazda-RX8 did not pass european emission regulations and was taken out of production.
 
Ops.... Out of the waybefore burning up (what piston rings do) it would be perfect but..... Such a good powerband when using a different displacement!!
 
The way I understand it +Colin Toal is on the right track. The materials have gotten better over the years so reliability isn't the problem that it had been. The biggest issue is that the time from Ignition to Exhaust is so short that still burning fuel is pushed out of the engine. This makes them inefficient (poor fuel mileage) and hard to keep within emission standards. Back in the 80's the RX-7's had 3 catalytic converters in series to try to finish the combustion process. In a piston engine each cylinder fires every 720° of rotation. So a V6 engine has 3 firing pulses per 360° of revolution. In a rotory engine, each rotor chamber fires once per revolution. (3 in 360°) And the RX-7 engine had 2 rotors so it had 6 firing pulses per revolution. That's why they make a lot of power in a small package. Mazda made some twin turbo, 3 rotor engines (9 pluses per rev) but as far as I know they were never imported to the US. Japan only.
 
but will the pressure after ignition move the mechanism in the right direction? seems a lot less likely than in the old design.
 
Wonder if you could feed the exhaust back into the engine for a second round of combustion..
 
Heat and clean air to fuel ratio, would be the biggest problems with that setup.......
 
Compression ratio is an issue with the rotary cycle. Otherwise, high revs due to concentric shaft in the center which is awesome. Overall, I like...
 
had a mazda rx7 with a A rotary engine awesome car lots of revs which transferred into plenty of power
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