Sorry. I was in too much of a hurry yesterday to explain clearly. I was late for something.
The figures I quoted are for K&N filters. The stock one is even worse!
Yes I got a vey small increase in power by fitting the K&N but top end power was still dropping off too fast just before each shift which did not match the dyno curve.
I did two things to improve things so i don't know which worked best.
I swapped out the 5/16ths fuel line I had been forced to use as a repair (between the mechanical fuel pump and the stock hard lines into the carbs) and fitted -8AN hose.
I also removed the air cleaner assembly.
My next run on the track was a disaster as that was when I lost a couple of push rods so I have no 1/4 mile time. But I can tell you my 1/8th mile never felt stronger.
I doubt the bigger fuel lines helped much because I never got to the end of the strip and the stock hard lines are less than 3/8ths anyway. So i am sure it was the effect of no air filter.
After that was when I went to the K&N website and got this formula;
CFM Formulas for Filters
Round: Diameter x Height x 6 x 3.14
Flat Panel: Length x Width x 6
Universal Round Taper: (Base + Top) / 2 = A
Take A x Length x 6 x 3.14
Universal Round Straight: Diameter x Length x 6 x 3.14
Square inches of filter required for an engine = CID x Maximum RPM / 20839
I have measured my 6 pack air filter to be 58-inches around and 2-inches tall. Unless the formula is not correct or I have made a mistake then this equates to just 696cfm of airflow.
Try it for yourself and see if we get the same result. I have a bit of brain damage at the moment and make mistakes all the time.
