Slightly strange head flow question.

Since you clarified that you were looking for a simple "calculation, here's some calcs you can run to determine your engines requirement and potential.

Of course, you could always fall back on 2 times the intake flow to determine potential HP. For example, running a 250 cfm intake port (head) will get you to ~ 500 HP.

On the 360 heads on a 318, without trying to start an argument or sounding disrespectful to other members, I can tell you that the absolute, all around, best street cylinder head upgrade was the 360 heads on a 318 - and everyone I've ever built made much MORE torque on the bottom end than any of the 318 heads and it revved like a 340. Why? Because the stock 360 head has excellent velocity and will work well with cams up to .508 lift with either a Torker or an LD-340 dual plane. In fact, these engines were more fun (sometimes) than my big blocks, and those little 318's were nearly indestructible. No one ever believed I was running a 318 with such a combo !

Anyway, here's some calcs that should get you started:

Solving For Air Flow Rate

CFM = CID X RPM X VE / 3456

VE = 3456 X CFM / CID X RPM

CID = NOS X SV

CID = NOC X 0.7854 X Bore (squared) X Stroke (To calc displacemet on strokers etc.)

HGV = HGCV X 0.7854 X Bore (squared)

PDV = (0.7854 X Bore [squared] X DPD) + (VPD - VPB)

CR = 1 + 0.7854 X Bore (squared) X Stroke / CCV + HGV + PDV

Injector Sizing Calc if needed:

ISH = HP / 16

Key below:

Where

VE = volumetric efficiency
CFM = engine air flow rate - cubic feet per minute
CID = engine displacement, size or volume - cubic inches
RPM = engine speed - revolutions per minute
NOC = number of cylinders
BORE = length
STROKE = length
HGV = head gasket volume
HGCT = head gasket compressed thickness
PDV = piston deck volume
DPD = deck to piston distance
VPD = volume of piston depressions
VPB = volume of piston bumps
SV = swept volume
CR = compression ratio
CCV = combustion chamber volume
ISH = injector size per horsepower
HP = horsepower

Again, I hope this helps.

Southernman