I've heard from a few guys that the Hemi chamber design allows the fuel/air flow to go straight out the exhaust on overlap. If you look through the intake port of a Hemi head without valves you can see a little daylight on the exhaust side of the head. I would think a wider LSA would help kill some of the overlap and keep the fuel in the chamber. Also the a/f mixture just tumbles out the intake valve and doesn't seem to spread to the sides of the pistons. The pistons get a carbon track between the valves and the quench areas are fairly free of carbon.