Horsepower By Valve Size
 

Does anyone know what the math formula is for figuring out the maximun horspower you can make with a particular valve size? I'm trying to figure out how much horsepower is possible with the 1.90/1.60 valves in my AFR 165's. I've done some research and it appears that the AFR 185 has the same exhaust flow as the 165 but a little more cfm on the intake. I'm assuming the increase is due to larger ports and intake valve at 185.

I want to know if I could get close to the same flow with porting but keeping the 1.90 valves or if I need to go to a 2.02 and then port the intake runners. I'm trying to work something out to buy Guy's 347 and I want to try and make mid to high 500 rwhp using my existing heads if I can buy it. I know I could make that if I moved to a set of 205's but that would be another $2000 that I don't have.

Any 500hp at the engine SB build that I've seen has at least 190s. 500 at the wheels? Jump up to the 200s with a solid roller no question.

I don't think a valve would really be the limiting factor, it's got to be the port behind it. A valve just covers a hole, and a 1.9" valve should flow as much cfm as a 1.9" pipe with an obstruction in front of it, minus the thickness of the valve stem. And obviously with a bigger valve there is more room back there to scoop out the port.

Have your 165s machined for 2.05s and 1.80s :D

A 1.90 valve can only flow so much. I want to know what that is. Also, I'm already making 471rwhp with the 165's through the catted H-pipe. If I remove it I pick up 4 mph at the track so I assume I'm making about 500rwhp with it.

Holy crap. You know how to build an engine. Solid cam? 91?

I'll post on my engine forum and see if anyone has any answers for you.

:popcorn:

Hydraulic roller with .498 lift and 220 at.050 with a 110 LSA. It made 436rwhp on 91 and 471rwhp on 100. I'll check out the link.

Boom! Could not have been a more perfect answer! There are like 4 calculators about valves on this page. http://www.wallaceracing.com/Calculators.htm

I think this is the one you were looking for specifically. http://www.wallaceracing.com/hp-valve-size.php