I just read that article and that figure 8 pattern on top of the piston is no cylindrical dish! Steve Dulcich, how did you let him get away with that?

On to the topic of piston top shape. One of the greats said that we need to remember the top of the piston is the bottom of the combustion chamber.

Larry Widmer, from his writings and work, believes there is a lot of power in the piston top. He also mentions shaping the chamber to push the gases toward the exhaust valve and leave as little clearance as possible around the intake valve.

One of the points that impressed me early in my study of spark ignition engines is that flame speed is relatively slow, in the same order of magnitude as the piston speed. It seems most of the really serious work of the past decades has been aimed at completing the combustion event more rapidly. The major way this is done is by use of squish.

R.