Enlarging PRP doesn't always help

Earlie A said
You are correct, maximum flow is not what is most important. It's more about velocity (from which port energy is derived) and shape. It would be nice to keep the port speeds around 300 fps average, but for a SM/Edelbrock style head on a large cubic inch motor, there is not enough area available to get the speeds that low.

From what I've been noticing from what I've been watching( I'm not a head porter: ), smallish engines at reasonable rpms eg.. 318-371 @ 5000-6500 rpms we have generally enough CSA available to us so it's of lesser concern, so getting the most flow for given size is generally beneficial, but once you start cranking up rpm especially with larger displacements gaining enough CSA seems to be the quest above all, like Darin's super stock hemi head that they spent countless hours in crazy mods not to gain even 1 cfm but to gain csa so they could shift like 500-600 rpms higher and probably spent $30,000 plus grand in the process.

To me it seems like CSA of the entire port and it's shape is most important and to slightly less extent cfm and volume are along for the ride plus we're generally not making full use of available cfm, 2-2.5 hp per cfm.

Earlie A said
The whole 'see how much flow I can get' thing is just a way to keep the testing interesting. You have to have a goal - something you are trying to achieve. That way you can look back at the end of the day and (sometimes) feel like you accomplished something.

Efficiency is a tough one to quantify. For instance - try to measure valve curtain area and really get it right.....

My guess is the csa around the ssr will be the ultimate cork since it can only be modified so much, and design the rest the port to be in balance with that, unless there's a specific need to push everything to it's limit, I understand this just research phase looking for those limits. Keep up the good work.

I appreciate you sharing your porting journey with us, one day I hope to learn enough to take a crack at porting my heads.