The lower crankcase compression ratio is what, about 1.6:1?
And stuffing the crankcase with a minimal backplate does little to raise thatcompressionratio so I am notsurprisedthat Duke Fox, George Aldritch or even<span class="Apple-style-span" style="font-family: Verdana, Arial; font-size: 13px; -webkit-border-horizontal-spacing: 1px; -webkit-border-vertical-spacing: 1px; ">Edgar T. Westbury found any difference! It not like the primary compression ratio where a quarter of a turn can make all the difference.

This is all about gas flow and keeping the mixture in its gaseous form, and the least amount of non port surface area the better.

Just think of the lower crankcase as part of the transfer system and not a storage tank as this is what modern designs do.<br type="_moz" /></span>