Regardless that the Blacktop head includes a additional open up combustion chamber (see “Head combustion- chambers”) it still has a greater static compression ratio (see “compression ratio”), this is solely as a result of piston structure. The Silvertop piston features a really compact dome with two deeply angled exhaust flycuts, https://toyota-4age-blacktop-engi04703.shotblogs.com/the-ultimate-guide-to-toyota-4a-ge-45388827