I think there are some other factors that go into this power equation besides CFM capability. I would be interested in seeing the pressure differential that the each combination made, as well as any velocity measurements. How many seconds did each combination take to stabilize at those flow numbers? I'll take a fast 569cfm over a relatively slower 623cfm. Time based rate of change is the key to torque(and HP). Also, what was the swept area of each assembly? What volume of air did each hold?
The stock setup might flow as much or more air on a flow bench, but how much work does the engine have to do to get that air from the fenderwell to the MAF sensor? Pumping losses and airflow velocity need to be accounted for.
Know what all those chambers on the sides of the air tube do? Reduce flow noise by reducing velocity.
mass flow rate in=mass flow rate out. mass flow rate=densityXareaXvelocity
for a constant density fluid(air), an increase in area will have a corresponding decrease in velocity.
Looking at the results, I think the leanest running (un-tuned) would be the ones flowing significantly more then the stock combo. The larger numbers(733 and 1077
) will trick the MAF by cooling the heated wire too fast, and the fuel/timing tables wont be enough to keep you from running lean. Most of the test intakes flowed within 10% of stock CFM, which the ECU should be able to account for, granted that the you have consistent fuel, a decent state of tune, a clean filter, good spark......
I hope my basic understanding is not too far from the truth
