The central part of the top of a piston, often raised in some engines.
The piston crown refers to the top of the piston. A piston can generally be divided into two sections (though the piston is a single piece). The lower part of the piston is called the skirt. The upper part, including the top of the piston that faces the valves and must handle the combustion of the fuel-air mixture, is called the crown. The piston crown must have the mechanical strength to withstand the forces of combistion, and must be made of materials that will withstand the heat of combistion. All this must come in a package that has limited thermal expansion so that the tolerances within the engine are tighter and performance is maximized.
Crown
Piston crown is the top, skirt is the side below the ring lands (ring grooves). The as you say, the skirt often has cut aways to clear the counterwieghts on the crankshaft.
A larger piston skirt to cylinder wall contact raises piston cooling. With turbo motors, they have piston oilers, they spray oil on the underside of the pistons, cooling the piston /crown.
cracked oil ring on piston
Hottest part is the piston crown....
wrist pin to crown . the area of cylinder wall the piston travels ,shirt to upper ring groove
compression rings.. while the bottom ring is known as oil ring .
rising piston compresses air/fuel mixture , then ignited at top, heat raises pressure, pressure on piston crown creates force, force over stroke = work
pre ignition , example : carboned up piston crown retains heat from previous burn and combined with compression , self ignites before firing point tending to stall rising piston
You can find an inexpensive tool at your local auto parts. This works best.
pre ignition , example : carboned up piston crown retains heat from previous burn and combined with compression , self ignites before firing point tending to stall rising piston