Though the Blacktop head encompasses a much more open combustion chamber (see “Head combustion- chambers”) it even now has an increased static compression ratio (see “compression ratio”), this is solely as a result of piston design. The Silvertop piston features a quite smaller dome with two deeply angled exhaust flycuts, https://titussxaay.thenerdsblog.com/37009598/the-definitive-guide-to-toyota-4age-blacktop-engine-for-sale