ORIGINAL: Sport_Pilot
The long stroke gives the expanded gas more time to push against the piston. Stroke [length] is what you plug into the formula to find torque, no..?
The piston is pushed for the same amount of time for a long stroke as a short stroke. That is totally determined by the RPM not the stroke. For torque you will find that this is the stroke times the pressure on the pistion. For a given stroke and the same displacement the long stroke will have less pressure, but a longer stroke so the torque will be exactly the same. However a long stroke has more friction loss, and poor breathing due to smaller valve or port areas, thus it will turn slower and must be timed for better torque. Thus the myth that you must go to a longer stroke to improve torque. That and the fact that diesels tend to have longer stroke, but that is give more clearance for the valves at a very high compression ratio.
The short stroke makes it's best power at much higher RPM than the long stroke design to be able to produce the same power. The short stroke simply leaves less time for the air moving in and out to complete their cycles versus long stroke. I doubt Mazdas' engineers would settle on the long stroke design for alky fuel unless they felt it was the most efficient way to extract the most power.