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Formula for: CFM = max RPM ?
Posted: August 15th, 2011, 8:29 am
by BADASYJ
I'm trying to find the formula that will tell me what the max rpms my 4.7 will get with a 390 cfm carb.
If anyone can steer me in the right direction I would appreciate it.
Re: Formula for: CFM = max RPM ?
Posted: August 16th, 2011, 7:13 am
by israelcj7
Re: Formula for: CFM = max RPM ?
Posted: August 16th, 2011, 1:37 pm
by Cheromaniac
The formula is Maximum rpm = (Carb cfm x 3456)/(Engine c.i.d. X VE)
If we plug in some numbers (assuming volumetric efficiency of 80% or 0.8):
Maximum rpm = (390x3456)/(284x0.8) = 5932rpm so your 390cfm carb is definitely man enough for the job.
Re: Formula for: CFM = max RPM ?
Posted: August 19th, 2011, 12:20 pm
by BADASYJ
Allright thats just what I was looking for. Thanks guys