Actual Rotary Displacement Request

[Barry Bordes]

Originally Posted by vex

That's an idealized otto cycle Barry. For all engines there's going to be descrepancies and variations from that. I don't think there's a p-v diagram out ther for the 13B at least not to my knowledge. I'll have to check the SAE papers.

Vex, I think the 2-3 line and 4-5 would change only slightly.
The piston engine's rod ratio will affect its shape vs. the Rotary's sine wave movement. (Dotted line-rotary, from Yamamoto's book)

[vex]

Originally Posted by Barry Bordes

Vex, I think the 2-3 line and 4-5 would change only slightly.
The piston engine's rod ratio will affect its shape vs. the Rotary's sine wave movement. (Dotted line-rotary, from Yamamoto's book)

I can't tell if we're missing each other on this. I'm not understanding what you're asking.

What I posted was a P-V diagram of the Otto Cycle (4-stroke cycle). The amount of pressure contained within the piston and the amount of volume it sweeps will be the only determining factor so long as combustion and heat rejection are kept the same.

What you provided is only one part of the P-V. We'd still need the pressure it sees prior to combustion, after combustion, and the adiabatic expansion and heat rejection.

Since no engine is ideal in the Otto Cycle the steps from compression up to combustion would be isentropic (it's a fair assumption; not great, but not as bad as adiabatic). After combustion it would be isentropic to the point of exhaustion--then depending on if there's a turbo in the way we'd have different pressures going on there. Intake would be dependent on stuff outside of the engine.

[Barry Bordes]

Originally Posted by vex

I can't tell if we're missing each other on this. I'm not understanding what you're asking.

What I posted was a P-V diagram of the Otto Cycle (4-stroke cycle). The amount of pressure contained within the piston and the amount of volume it sweeps will be the only determining factor so long as combustion and heat rejection are kept the same.

What you provided is only one part of the P-V. We'd still need the pressure it sees prior to combustion, after combustion, and the adiabatic expansion and heat rejection.

Since no engine is ideal in the Otto Cycle the steps from compression up to combustion would be isentropic (it's a fair assumption; not great, but not as bad as adiabatic). After combustion it would be isentropic to the point of exhaustion--then depending on if there's a turbo in the way we'd have different pressures going on there. Intake would be dependent on stuff outside of the engine.

I meant only that the Rotary's diagram would look similar.
Barry