Regardless that the Blacktop head includes a extra open combustion chamber (see “Head combustion- chambers”) it nonetheless has a better static compression ratio (see “compression ratio”), this is purely due to the piston style and design. The Silvertop piston contains a really little dome with two deeply angled exhaust flycuts, https://4ageforsale29618.blog5star.com/31766009/the-basic-principles-of-blacktop-20v-4age