Engine/Transmission (1998.5 - 2002) Why I said "To Hell with the K&N"

[kbond]

What's the formula?

Originally posted by Gary - KJ6Q

When exposed to more airflow than designed for, paper elements distort, and may actually rip apart - VERY bad in a dirty environment - I actually destroyed an engine in that scenario. Oiled filters like the K&N will stay intact, but the excessive flow of air volume simply FORCES any dirt particles on thru the element material...



Keep in mind that with ZERO boost, our engines suck 360 cubic inches of air per cycle - at 14. 5 PSI boost, that volume doubles to 720 or so - and at 30 PSI, doubles again to about 1440 Cubic inches - and I'm pretty certian you run more peak boost than that to obtain your power ratings - and seriously doubt that K&N pictured is rated anywhere NEAR that figure! Not necessarily a bad filter - just a bad choice for your application - and you mighta been FAR worse off with a paper element - and you're right, ANY similar sized oiled element would undoubtedly have done the same thing!



Get the RIGHT, properly rated filter to match your requirements!

Hi Gary,



Curious on the formula as I have the AFE mega cannon that claims 820 cfm. Does that mean for every Cubic foot I have 144 cubic inch of flow? Doesn't seem right as that would give me 118080 Cubic inch of flow??

 

[jwinnie]

I noticed some people (Gary ) were interested in the marine version of the BHAF, Fleetguard #AH19002. I was too until I found This thread . Mark Kendrick has a good post. If his info is correct, that filter has about half the flow rating of the regular BHAF.

Just FYI,



John

 

[ROADWARRIOR]

I talked to a tech. person at Fleetguard about the Marine version. They told me the standard bhaf was 600ish cfm and the Marine version was 900 something cfm. I don't have the part numbers handy, but they are the same size. The 400 something flowrating was for the smaller 8 inch diameter filter.



Dan

 

[Gary - K7GLD]

"If his info is correct, that filter has about half the flow rating of the regular BHAF. "



HMMMm - that's a pretty significant reduction in flow compared to the standard BHAF... .

 

[JohnE]

whoa guys



A filter with an internal cage as the marine filters can have a higher CFm rating compared to a conventional filter but also at a higher WG level. WG is the pressure difference between outer and inner.



Don't forget Fleetguard stated the filter media is the same for the filters. I did a visual on both and they appear the same.

 

[DPelletier]

KBond,



1728 cubic inches = 1 cubic foot (12"x12"x12"). To find air flow you need to multiply the engine size in cubic feet x RPM. eg. 360 cu in = . 2083 cu ft. x 3100 RPM = 645. 83 CFM (Cubic Feet per Minute). BUT this is assuming atmospheric pressure of 14. 3 psi, ie, no turbochargers or other air density enhancements. If you had a turbo and were running 14. 3 psi, you would have twice the CFM (there are other variables, but for clarity's sake). A 360 ci engine running double atmospheric pressure (14. 3 psi of boost) would use the equivalent air as a 720 cu in regularly aspirated engine. In order to double the apparent size from 720 to 1440 cu in, you would need to run 42. 9 lbs of boost (plus atmospheric of 14. 3 for a total pressure of 57. 2 psi or four x reg. atmospheric pressure) .



Dave