Airflow to Cubic Inches

273 said
Is that formula ideal ? Don't know but it seems reasonable.

Definitely there's no ideal air flow just to cubic inches, you have to factor in rpm and volumetric efficiency for what I call dynamic displacement the size of the engine at any given rpm (cfm).

Basically cid x rpm / 3456 x ve% = cfm is what you engine roughly dynamically displaces but there's no easy way to figure needed head flow from that.

Are you trying to figure out head flow for any particular build ?

ch1ll said
That’s why porting and flowing a head without porting and flowing the intake manifold is so important. A well ported RPM airgap will only flow 230 ish cfm. Its the total combination. If your port flows well but your air speeds vary too much in different areas of the port, you will lose hp. If you flow well but your port is too big, you will lose port energy and lose hp.

273 said
There's a formula cid x rpm x 0.0009785 / amount of cylinders = cfm

So 360 x 5500 x 0.0009785 / 8 = 242 cfm

To clarify. I am going to build a 440. I have a stroker kit to make it 493. JE dome pistons will have CR around 12.5 :1. Looking to produce IN THE RANGE of 675 TQ and 650 HP.

Therefore; 440 x 6200rpm x .0009785/ 8 = 334 cfm

Brodix; B1-BS - 2.20 intake @ 650 flows 295
Brodix; B1-MO - 2.30 intake @ 650 flows 382

Powerport 270; 2.19 intake @ 650 flows 347 cfm

440 SR; 2.19 intake @ 650 flows 360 cfm.

It did occur to me that you could have volume but that doesn't make it efficient. I have heard the B1-MO have a design that increases airspeed in to the cylinder. I do not have an understanding of the other heads (you know jack of all, master of none. Just enough knowledge to get into trouble). With the variances in CFM, relying on manufactures claims, technical aspects of heads, and my lack of experience, what head?