[My5ABaby]

Originally Posted by Libor

Rotary maybe had slight edge in this, some 40-50 years ago

Bare engine may appear compact and light, but whole package is what counts. Engine, intake and exhaust manifolds, cooling system, muffler system, it all counts.

We can´t just say that certain engine is compact and light, when all needed accessories through their bulk and added weight doesn´t make it such viable powerplant.

I would look for advantages of wankel rotary elsewhere

I'm not saying the rotary engine is compact and light. I'm saying that what is needed to make the engine run as intended (i.e. manifolds and engine) is what should be measured. If, as it sits in the car, a 13B weighs 350lb (or whatever), that's what we measure. If, as it sits in the car, an LS6 weighs 450lb (or whatever), that's what we measure.

Originally Posted by vex

You mean like TDC to BDC

Like the weight of the engine including manifolds and such (excluding other drivetrian - tranny etc.) / the horsepower and torque.

Perhaps all this is taking it too far off subject though...

Originally Posted by RotaryGod

The rotary engine as rated by Mazda is 1.3 liters because each individual rotor, following one face of one rotor through the complete cycle, has a swept displacement of 654cc or .65 liters. Multiply this times 2 rotors to achieve 1.3. Since this only accounts for 2 of the total of 6 rotor faces, we multiply our answer by 3 to get an actual displacement of 3.9 liters. However since the rotary engine is a 6 stroke engine and not a 4 stroke engine since it takes 3 complete eccentric shaft revolutions to fire all faces instead of the typical engine's 2, it only does 66% the work of a 4 stroke 3.9 liter engine. Calculating for this we divide 3.9 by 1.5 to get a total of 2.6 liters equivalent work to a 4 stroke piston engine. All of these, from a 1.3 liter in physical size package.

This makes sense to me. Perhaps it's because it's put in non-engineer speak, but whatever.