Hello everyone,
is there an ideal cfm for the sohc heads to flow on our cars in modified form? Furthermore, is there a number not to exceed in na form?

I’m building an na engine with a 272* cam and 10.7:1 compression. +1mm intake and stock size exhaust valves. Turbo valve springs. MSDS header. Molnar rods. Microsquirt with all new harness. Intake and head port-matched to gasket.

Further, are there ideal areas that need work specifically in the NA heads? I understand that flow under boost and vacuum can change the flow in the port.

 

My flowbench testing has shown that a NA head and a 951 head flow essentially the same in stock form. The one to use for both NA or boosted engines is the NA head since there's no ceramic to fail, and you can reshape the NA exhaust port since it's all aluminum.

The porting is very specialized work, and only a very few can make successful improvements. It's certainly not intuitive. All too often what you get is a "pretty" port that results in marginal performance gains (or losses). Leave that work to specialists at a porting (only) shop or a performance engine shop that specializes in head work. Spend your money wisely!

 

Michael well stated