Rise of the Phoenix

iTrader: (27)

I know that the benefits of the PRC and TFS heads are that they allow for more piston to valve clearence with different valve angles, but does this also increase air flow? AFR heads have the stock 15 degree valve angles, while the TFS heads have 13.5 degree valve angles. Peformance Induction heads sport 11 degree valve angles, while the PRC heads offer 13 degree valve angles. If the valve angles do help with increased air flow, then how do the AFR heads have such great flow numbers? I'm just a little bit confused as to what all the benefits are of having heads that offer the "non stock" valve angles.

JUSTINSWS6

I think the prc 215 heads out flow afr 215

wildcamaro

iTrader: (15)

The best way to explain without the use of engineering theorems and terms is like this...

Airclow doesn't like to make make 90 degree bends...that's why the basic idea is the less of a bend the better that's why you see that race heads are less degrees than the street/strip heads, same is true whenever comparing sbc gen 1 heads with LS heads, less of a restriction for air flow...another reason GM used cathedral port heads which Allow a decrease in angle...

Rise of the Phoenix

iTrader: (27)

So if what you are saying is right, then the PI heads will flow the best because of the 11 degree valve angle?

redtan

iTrader: (5)

If all else equal sure, but that's rarely the case. There are a lot more variable that make up airflow, valve angle being one of them. Unless a company makes the same exact head but in 11* and 13* you can't compare them. A 15* head might flow more than an 11* head because of a ton of other reasons.

Rise of the Phoenix

iTrader: (27)

Ok, so if you had a set of AFR 215's, TFS 215's, PRC 215's and PI 215's sitting in front of you and were told you could pick one set for free, which would you choose and why.

wildcamaro

iTrader: (15)

Yea there is tons of variables, when improving flow a lot of different stuff can have effects...

Rise of the Phoenix

iTrader: (27)

Maybe Tony and Texas Speed can jump in and elaborate???

chrisfrost

iTrader: (8)

The way I see it the larger angle will flow better as with the valve open there is more of a straight shot into the cylinder but with the trade of less ptv clearance but I have been known to be wrong ,,,,,,,,,,,,,,way back in 48' ,,,,,,he he oh ya ,,,,,I was'nt even born until 64' .

FASTFATBOY

iTrader: (23)

Its all about the angle of the turn the air has to make to get in the cylinder. Its the tilt of the valve in relation to the top of the piston.

You stand the port up higher with less valve angle and it takes the short side turn away.