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

The side-by-side plugs are probably done for redundancy.
Mazda's 16X  paper describes the best width and length ratios  and their effect on flame speed.
When the flame front touches the side walls or the adjacent spark plug's flame front it slows down.
The 12A has the proper ratio. The 13 B does not.
As Dale Davies just pointed out the 16 X would return to the proper ratio.
Barry Bordes

Do you have a scanned copy of that paper?

Paul Lamar

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