Warm Up Times of Radial Engines.

[Crumpp]

The purpose for warming an engine is to get the oil warm so that the bearing surfaces are lubricated properly.

True but even more important is the fact aircraft engines have what is called a "choke grind" cylinder.

That means the cylinder is wider at the base and narrower at the head when cold. When warmed up, the head is hotter than the base so it expands and the cylinder walls become straight.

If you operate your engine without it being warm, then you are really putting excessive wear on the head, pistons, and rings.

Originally Posted by Crumpp

True but even more important is the fact aircraft engines have what is called a "choke grind" cylinder.

That means the cylinder is wider at the base and narrower at the head when cold. When warmed up, the head is hotter than the base so it expands and the cylinder walls become straight.

If you operate your engine without it being warm, then you are really putting excessive wear on the head, pistons, and rings.

Yes. That's a good point, but what I'm saying is that on the engines I've run by the time the oil is warmed up enough to rev up the engine the cylinder head temps are good to go. That's all.

[TomcatViP]

Basically the cylinders need to absorb the heat first before the engine start heating the oil.

Hence when the oil temp is good, the cylinders are already fit to go