I've got an old HPI engine that has a piston with a machined hole in one side. I wondered what it was about for a long time, until I examined the block and realized the main transfer port in the sleeve didn't have a corresponding channel in the block. Then I realized the hole in the side of the piston was there to allow the intake charge to travel up through the center of the piston, through the hole in the side, up through the main transfer port, and into the combustion chamber.

So my question is: This engine only seems to run really well when I lean it out to the point that the glowplug temperature is higher than I'm comfortable with. (like, almost 300°F, whereas I usually aim for 230-250°F.) But if the intake charge is passing through the center of the piston on its way into the combustion chamber, then presumably it's cooling the piston in the process. So should I still worry about seeing higher-than-average temperatures at the glowplug on this engine?