[Porsche-O-Phile]

I agree but is the air in contact with that stuff long enough for it to make an appreciable difference in output temperature? I'd think not - the slug of air is only in the cylinder for a fraction of a second so I wouldn't think that there'd be a heck of a lot of thermal transfer going on (metal to air). Of course if someone can show a way this could happen I certainly could be wrong here. I just don't see a lot of thermal transfer happening between the hot metal to the air (or vice-versa) where it'd make a difference.

Air compressors I've used take a while for the finned area around the piston to get hot, which I imagine is because it takes a lot of cycles of compressive heating of the air inside to warm up the metal (again tending to lend validity to there not being a lot of transfer there). And a lot might be due to simple friction (piston-cylinder) rather than compressive heating effect of the air inside anyway.

Bottom line is I'd bet 99% of the temperature of the output air has to do with compressive heating effect and 1% (if that) due to thermal transfer between the heated-up case and the air in the cylinder.

Yes, no?