[Qem]

Wall thickness increasing by x increases cross section/power by x^2, but also increases chamber volume/workload by x^3. So workload outruns available power. It's because of this people abusing steroids get heart failure eventually.

[fluoridation]

>chamber volume/workload by x^3. So workload outruns available power.

What do you mean by workload? Are you referring to the oxygen cost per stroke, or what?

[Qem]

Power demand. Volume pumped each cycle * (systolic pressure - diastolic pressure) / time.

[fluoridation]

Mate, I have no idea what you're saying, or how it's a constraint on size.