Thank you, I was in a real mood the other night, and I have people always jump my **** on the forums. I am sorry for not being more civil, but it would have pissed me off to start over and retyped the whole thing. I dont want to start a debate about displacement, Although this has always confused me about rotaries, so I went with what I know.

If there is a standard way to figure displacement for a rotary, I would be pleased to know. I am not trying to debate, basically I want to know how Mazda figures it to be 1.1 Liters.

Sorry to thread jack...

 

I'm going to venture a guess that if you have an engine apart, you could assemble the front iron, #1 housing, e-shat and rotor, lay it out with the e-shaft pointing up, the rotate the rotor until you see the maximum volume in the chamber and measure it. I would also venture a guess that the maximum volume occurs when the 2 opposing rotor tips are horizontal/level to the world, if the engine was stood up. Hardest part would be keeping enough of a seal so the liquid didn't seep out before the chamber was full and an accurate measurement could be taken.

Loki, I believe I owe you an apology on the compression comment. As I thought about it more, the more volume you cram into a finite space the more the CR raises. The way I was looking at it when I posted my comment was the fact that you cannot increase the volume of the combustion chamber on a rotary, as you can a piston engine. And now that I think about how I came to the conclusion on the earlier post on CR, I don't know what I was thinking. I've got to quit staying up 24 hours +.

I'm sure there are probably some good technical papers out somewhere that expain how engine size is figured in a rotary, I haven't come across one. Comparing a 4 stroke engine to a rotary, cu. in. for cu. in., to me just does not compute. What a 4 cycle does for one combustion event, it takes a rotary, looking at it in an odd way, only 3 steps. This idea is, of course, discounting engine revolutions per combustion event per combustion chamber.

If this doesn't make any sense, yes, I still need some sleep.

 

Displacement or swept volume on a rotary is calculated the same as a piston engine. The difference between the maximum chamber volume (which occurs at 180* of e-shaft rotation) and minimum chamber volume (0* degrees e-shaft rotation) times the number of rotors.

 

Since I am too lazy to calculate the difference in rotation between the e-shaft and rotor, where does this position the rotor when the e-shaft is at 180*?

 

When one of the apexes is pointing straight down.

 

Thankyou sir, that was my guess.

The 180* or e-shaft rotation makes sense, when comparing it to how displacement is determined in a piston engine.