[lust4speed]

Except K&N has taken the folds into account with their stated flow rating of 6CFM per square inch of (exterior) filter medium.

Using the 6CFM figure, my 121 square inch sized round filter would flow 783CFM -- which wouldn't be enough to satisfy the needed 829CFM requirement of the 462 at 6,200 RPM. Since we proved on the dyno that the filter size was sufficient up to 6,500 RPM, I'd say that their estimate is somewhat conservative. That nice even 6CFM number was probably rounded down. I'd say that it would be entirely safe to use the 6CFM figure for figuring minimum filter size.

I avoided splitting hairs and simply installed a 5x14 K&N filter on the drag car. Probably didn't need it, but had the room so why not?

[[email protected]]

thanx for the info Smitty

i've heard that the xtreme top disrupts airflow which robs HP. anyone have any dyno proof one way or the other?

thanx
Kevin

[77 TRASHCAN]

Originally Posted by 535 tall deck

thanx for the info Smitty

i've heard that the xtreme top disrupts airflow which robs HP. anyone have any dyno proof one way or the other?

thanx
Kevin

We don't need no stinking dyno (in this instance), we have Cliff...

[smittyseng]

Originally Posted by 535 tall deck

thanx for the info Smitty

i've heard that the xtreme top disrupts airflow which robs HP. anyone have any dyno proof one way or the other?

thanx
Kevin

I made pulls with a 3x14 w /extreme lid, 4X14 w/extreme lid, both with steel top and the 3x9 with steel top. In my application, the extreme lid did NOT hurt performance, it helped when running the 14X3 slightly BUT remember, I am running efi so no fuel or air bleeds to get disrupted or anything either which is what I hear happens, Smitty

[Engo]

Originally Posted by lust4speed

Except K&N has taken the folds into account with their stated flow rating of 6CFM per square inch of (exterior) filter medium.

Using the 6CFM figure, my 121 square inch sized round filter would flow 783CFM -- which wouldn't be enough to satisfy the needed 829CFM requirement of the 462 at 6,200 RPM. Since we proved on the dyno that the filter size was sufficient up to 6,500 RPM, I'd say that their estimate is somewhat conservative. That nice even 6CFM number was probably rounded down. I'd say that it would be entirely safe to use the 6CFM figure for figuring minimum filter size.

I avoided splitting hairs and simply installed a 5x14 K&N filter on the drag car. Probably didn't need it, but had the room so why not?

Were did you get that 6cfm figure from? Is it an approximation for all KN filters or an exact no valid for the 3x9 filter only?

Reason I question this, is the fact that even the foldings on different sizes KN filters are different. I have the KN 3x9 filter were the foldings are 10mm deep and a KN 16x3.5 filter were the foldings are twice as deep 20 mm. Because of this fact, the 6cfm figure cannot be correct for both these filters.

[smittyseng]

Originally Posted by lust4speed

Except K&N has taken the folds into account with their stated flow rating of 6CFM per square inch of (exterior) filter medium.

Using the 6CFM figure, my 121 square inch sized round filter would flow 783CFM -- which wouldn't be enough to satisfy the needed 829CFM requirement of the 462 at 6,200 RPM. Since we proved on the dyno that the filter size was sufficient up to 6,500 RPM, I'd say that their estimate is somewhat conservative. That nice even 6CFM number was probably rounded down. I'd say that it would be entirely safe to use the 6CFM figure for figuring minimum filter size.

I avoided splitting hairs and simply installed a 5x14 K&N filter on the drag car. Probably didn't need it, but had the room so why not?

Remember though too, if a air filter will flow 783 cfm at a given vacuum like 1.5" or so (haven't found a EXACT number anyone will admit to) that it CAN and WILL flow more BUT it will create a vacuum inside the air cleaner affecting the tune of the carb AND it will reach a point where it goes from being a slight restriction to a terrible resriction, Smitty