Although the Blacktop head incorporates a additional open up combustion chamber (see “Head combustion- chambers”) it however has a higher static compression ratio (see “compression ratio”), this is only because of the piston style and design. The Silvertop piston encompasses a pretty small dome with two deeply angled exhaust flycuts, https://toyota-4age-blacktop-engi61481.ja-blog.com/31392460/indicators-on-4age-20v-turbo-engine-for-sale-you-should-know