RX-7 and RX-8 have two rotors. One rotor is 654cc. Two rotors are 1308cc. The rotary engine makes power by the rotary motion of the triangular rotor. Please look lower figure. It is an explanation of the Rotary Engine.
The rotary engine has many advantages.
1, Rotary engine is tiny and is light in weight.
2, Rotary structure is straightforward and is few parts.
3, Rotary engine has rotary motion but not reciprocating motion. The reciprocating engine is inefficient because the reciprocating engine needs to change back and forth motion to rotary motion. But a Rotary engine is rotary motion from the beginning.
4, Rotary motion has more small oscillation than back and forth motion.
5, Rotary engine spark many times more than reciprocating engine by rev. This is the reason for big power.
6, Rotary engine can get more power easily. Because the rotary engine is tiny and it is straightforward to add more rotor.
The rotary engine has many advantages. But the rotary engine has not come into wide use. Why? Because a rotary engine is a gas guzzler. The rotary engine's fuel expenses are about 4 miles a litre. If you drive roughly, fuel expenses go from bad to worse, about 3 miles... And the generation of heat is high because a rotary engine makes big power from a small engine.
Indeed, it's not widely in use, but isn't the main reason for this is, that Mazda won't license the technology to other manufacturers?
Gas guzzler or not, i think a lot of manufacturers would like to experiment with this concept.
Actually, i wouldn't be surprised if many manufacturers have their own prototype ready to be used, when Mazda will start handing out a license.
Hmm, i wonder if this technology could also be adapted to be used with diesel.
The reason of not widely in use is a poor mileage simply. In point of fact, Mazda don't use Rotary engine to all of their cars. Rotary engine's car is a RX-8 only now. If Rotary engine is a economical, all Mazda's cars will be Rotaries.
And Mazda don't think license the technology to other manufacturers. Because nobody want to the license. On the contrary, there is a manufacturer that demand to stop the production of Rotary engine. It's the Ford. Ford is a main stockholder and parent company of Mazda. Ford could get the Rotary technology, but they regard Rotary as waste. And Ford decided to stop the production of Rotary engine.
But some of Rotary engineers made efforts to survivor. And they improved Rotary engine to more economically. This is the new engine of RX-8.