Way back when the 2 most common mazda wankels were the 12a and 13 b. I believe they also made a smaller than 12a engine for the r100 and of course we all know about the 3 rotor cosmo engine. The difference between the 12a and 13b is
the width of the rotors. fatter rotor, more displacement. does anyone know if the length of the rotor is equivalent to stroke in a piston engine? I'm sure there are computer models mazda has that can simulate any configuration. The renesis is just a very much improved 13b. Wonder if Mazda will give us a different engine. Wonder if
an engine with a longer "stroke" would produce more torque?Just some friday morning musings...

 

no

 

As rotors get bigger, rpms must be reduced because the combustion zone is in motion, and you are limited by how fast the flame-front of the combustion charge can move. As you increase rotor diameter the speed at which the rotor faces move relative to the housing at a given RPM, increases rapidly.


from Wiki:

 

Driving at the speed of heat has a limit. But fortunately for us it's still pretty quick.

 

they could go to 15b 1.5 litre with no flame front issues.

 

Nubo, Thanks for the wankel history! Zoom, 15b probably fatter rotor easiest to acomplish wouldn't you think? I'm still curious if increasing the diameter instead of width would be analagous to increasing the stroke hence more torque. What I'm wondering is if (hypothetically) 2 15b engines were developed one of them by increasing rotor width and the other by rotor diameter, would the second engine produce more torque than the first? I'll dig around and find the answer. Remember when GM was trying to develop the rotary and failed back in the 70's? Anyone know if they did it from scratch...or did they copy Mazda? Anyone know what was wrong with their engine? (other than having GM engineers at the helm )

 

Ding Ding Ding..............ZOOM said 15B...........thats where we are going!!!

 

FYI, that engine was the 10A

 

Some one should tell Wiki you don't drive pumps on natural gas pipelines, you drive compressors. Pumps are for liquids.

Mike

 

Wiki fails at facts.

 

only if they arent corrected. agoodcave could go to the article himself and correct

 

Ok, corrected.

Mike

 

Flamefront propogation ranges between 1300 to 1800 feet per second in a piston motor depending on the fuel mixture, compression, and heat. Simply put, it's limited by the speed of sound although the fuel has some effect on velocity at the kernal boundary.

Large industrial diesels have the same problem but they tend to gain efficiency with larger scale - just can't turn as high of RPM.

Using side ports with wider rotors is similar to adding displacement without making the valves bigger. It will pump more just not proportionally to the displacement increase.

The real challenge for the rotory is to take more heat out of the combustion cycle. Too much heat is exhausted compared to a piston motor. Mazda found some good efficiency gains in extracting more energy from the heat by going with the side ports (sans peripheral port) and eliminating the intake-exhaust overlap.

I'm betting down the road they come out with a sequential chamber shutdown for cruising speeds.

I'll keep mine for at least 5 years and I'll bet the next generation is worth waiting for.

 

the will not do DOD or chamber shutoff that was aksed and answered in public. when they do that its official

 

GM had a 6.4L 4 rotor engine in the early 70's... if they could have figured out the reliable solution to the seal issue like mazda eventually did, it would still be the most powerful stock rotary engine in a street car (420+ hp).

if you can't do the math, thats 1.6L PER ROTOR... flame front issues

 

there was also some sucess by Mercedes with our .6L per rotor design...

http://www.worldcarfans.com/classics...ml/country/gcf

The performance of the C 111 even with the three-rotor engine was convincing right from the start. In 1969, the Wankel engine developed 280 hp from 600 cubic centimeters of chamber volume per rotary piston and gave the car a top speed of 260 km/h; with this engine, the car accelerated from standstill to 100 km/h in five seconds. The C 111-II of 1970 was powered by a large four-rotor Wankel engine which developed 350 hp and gave the car a top speed of 300 km/h. The second C 111 accelerated from standstill to 100 km/h in highly respectable 4.8 seconds. While some of the engines in the C 111-I cars had still featured dual ignition which was difficult to adjust, the four-rotor engine was equipped with single ignition exclusively. Both engines were direct-injection units
....

In retrospect, Dr. Kurt Obländer, head of engine testing in the C 111 project, described the Wankel engine as follows: “Our four-rotor engine with gasoline injection represented the optimum of what could be reached with this engine concept. The multi-rotor design called for peripheral ports for the intake-air and exhaust-gas ducts. We were able to solve the difficult problems in engine cooling and engine mechanics by technical means. But the main problem of the concept, its low thermodynamic degree of efficiency, remained. Due to the elongated, not exactly compact combustion chambers, fuel economy was poor, resulting in high fuel consumption and unacceptably high pollutant emissions. These drawbacks were inherent in the design principle.”

 

only if the engine is wider, but the engine can be bigger in all dimensions

 

you know something? dont you?

 

I think he does know something at least we are all hopeing so.....

 

Ok...you guys know and understand way too much!! Just kidding....interesting read!