The 13B NA Power Thread.

drewski86 · 12-11-2008, 02:51 PM

70% of the intake port area is the general rule of thumb. Don't have any facts but I've heard that number thrown around serveral times.
Moving port opening lower reduces torque as the charge spends less time in the chamber
Moving the port up increases overlap. Good for top end power, not so good for low end light throttle.
Moving the port sides out increases port area, and decreases surface area to support the seal as it crosses the port.
A rounder port will make less power, but have a broader powerband.

12-11-2008, 02:51 PM	#1
drewski86 Slow Join Date: Jun 2008 Posts: 38 Rep Power: 0	70% of the intake port area is the general rule of thumb. Don't have any facts but I've heard that number thrown around serveral times. Moving port opening lower reduces torque as the charge spends less time in the chamber Moving the port up increases overlap. Good for top end power, not so good for low end light throttle. Moving the port sides out increases port area, and decreases surface area to support the seal as it crosses the port. A rounder port will make less power, but have a broader powerband. Last edited by drewski86; 12-11-2008 at 03:10 PM.