Cylinder Head Porting and Power Production

Just wanted to update on the exhaust port question I asked early on. I apologize if this is ridiculously obvious to some here but looking at it this way helped me to see things more clearly.

Anyway, the presumptive reason the intake gets focused on when porting (and generally why the intake valve is larger than the exhaust) is because of pressure differential.

It is much harder to fill the cylinder with the intake charge because you are relying on atmospheric pressure to do it. That pressure is reduced further (vacuum) in the intake tract when the piston is pulling down so it makes sense that any extra volume of the A/F mixture combined with a less obstructed pathway into the cylinder would clearly help to overcome the lack of pressure.

But once combustion occurs and the mixture is pushed out, the pressure of the mixture becomes much greater so the extra volume is not needed. Making the pathway less obstructed is obviously beneficial in both instances but again, the exhaust port volume is not as important. I'll be honest, I never thought about it like that.

Carry on.