There is a lot of science involved with engine design. That's for sure. 99% of us just use what the engineers designed. They must have had a reason for what they did and why. It could be for power or economics and ease of manufacture. It comes back to How much power do I need and can afford. The engine brain surgeons can always squeeze a few more ponies out of an engine but at what cost? If you have the know how, a machine shop, and want to experiment go for it.The rest of us will just try our best to bolt a combination of parts together that we can afford and that works. Sometimes that's the smartest thing for us to do.