Slightly strange head flow question.
OK - gotcha on the lift ratio and the relationship between valve lift and runner size.
Maybe if we compare identical style heads - say Edies - but one set is ported to flow 300 @ .600 and the other 270 @ .600 -
What sort of difference in HP could be expected with the cam under discussion....Any improvement at all?
I like the wall's answer since I know what he's talking about on a technical level. *There are formulas for this and he uses them.*
it's about the VE, or in lamens terms -parts combo lol
and really, if you are lifting the valve .540, what ever the heads flow at that lift or just below say .030 u are gonna get/access if you're lucky enough to have the rest of the parts and mods done to achieve a better VE, and yes csa will effect hp/rpm....let alone air speed differences/port distribution...yadda yadda.....
You can say it's about parts and compression, lift, the moon and the stars, but really it ALL comes down to VE.
And again....if you not living at that lift.....those numbers mean dk.
The other thing is this......rhs heads are restricted to a shape that fits into a stock casting still using the push rod pinch, the closed chamber is great and does make some horse power.....but keep it real, the j head ported can go the same int numbers as an rhs head and it helps to have someone who's works with oem heads port them in the 1st place...
btw When I pick up an rhs head it feels like Im picking 1 1/2 oem heads lol, they have sooo much extra meat in them, good heads though.