Originally posted by PunkRock
And you are wrong too. The 13B and the Renesis would be 2.6l if they were piston engines. Borrowing heavily from the May 2003 issue of Sport Compact Car, here's why.
For nerds only:
Displacement is the volume of the combustion chamber at its biggest point, minus the volume at its lowest point. Each rotor has 3 combustion chambers, and the rotor turns at 1/3 the speed of the eccentric shaft (crankshaft for a piston engine.) With the 3 combustion chambers, each rotor has an intake stroke, and an exhaust stroke per revolution, a bit like a two-stroke piston engine. This is where you could say a 13B and a Renesis equal to 1.3l.
Problem is, the 13B and the Renesis aren't two-stroke engines. It has separate intake, compression, power and exhaust strokes, classifiying it as a four-stroke engine. On a four-stroke engine, there's only one intake stroke for every two revolutions, so, displacement is how much combustion chamber volume is sucked in during two revolutions. For a rotary engine, with one intake stroke every revolution, you have to measure two combustion chambers per rotor, and not just one, giving you a 2.6l displacement.