To get the 16X displacement and they also narrowed the rotor width. They are doing that after finding out the flame propagation does not get all the way to the sides when the width is over 75mm. The 13B is 80mm.

To increase displacement from 1146cc (12A) which was 75mm wide rotors, to about 1600cc the eccentricity and radius need to be increased. E of 17.5mm and radius of 122.5mm which is up from 15 mm and 105mm. E17.5,R 122.5, W 70 gives 1560cc. E 18, R 126, W 70 gives 1660cc. Either would increase torque and help the combustion efficiency.

Dale Davies

They did not try side by side plugs. Austro engines has a wide rotor with
plugs side by side.

Paul Lamar

If you pushed the rotor width to 80mm and dual s x s plugs with your coils would give 3.6 to 3.8 liter displacement with gobs of torque. For autos run lower RIM for a bit better fuel economy.

Dale Davies

You mean wider than 80 MM right?
The current displacement is 2,6 liters.

For 3.9 it would be 120 mm wide.

Paul Lamar

No. I was referring to an engine as supposed of the 16X with more eccentricity and radius. Then with 80mm width the 13B or Renesis apex seals would work.

Dale Davies

The Mazda engine factory is estimated to cost 2 billion dollars to replicate.
It is highly specific and designed to do the job of making the 13B.

You need a VERY VERY good reason to change the geometry.

I don't think the 16B is worth it. It is far lower cost to just add more spark plugs
and a better transmission. The Mercedes Benz transmission in my Motor Home is a hydraulically
shifted manual transmission. It works extremely well and it is much much more
efficient than the old and obsolete torque converter.

Paul Lamar


The whole deal to change the eccentricity and radius would be major. You have to think about new timing gears also. If/when Mazda comes out with the 16X the problem of rotor housings with dual plugs would be fairly simple. Wider rotors could be dealt with. If a person was to think about the cost to develop a larger engine by changing the eccentricity and radius, changing the eccentricity to 20 or 25 mm with the radius correspondingly 7 times that for a much larger displacement. Then the torque would be way up and at a cruise RPM of 6000 you would have serious aircraft power.

Dale Davies

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