Jalop did a great article explaining DOHC engines not too long ago that explains this. Basically, it’s geometry. Two cylindrical shapes of identical circumference inside another, larger cylinder = more surface area than a single cylinder with identical volume to the first two. More surface area means more fuel and a…

This comment just sold me on buying a new copy at full price. I was originally going to wait for a cheap used copy but this man deserves my money