• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

EFI Filter Size or CFM Rating

BroncoinAlaska

Sr. Member
Joined
Mar 26, 2007
Messages
509
Loc.
San Antonio, TX
Tunning the EFI setup in the Bronco and have noticed that the cone filter is choaking off the intake and the moter runs much better with the filter off. I have a 5" cone K&N with a 3" inlet. The mustang guy that i took the Bronco too sugested a sheild and a filter that can flow 880 cfm for my application.
The sheild is to keep the air off the filter that is being kicked around the engine bay from the explorer fan.
Here is a breakdown of the EFI parts
Throttle body 70mm
MAF 76mm
Trick Flow Upper and lower Intake
30# injectors red colored

Here is the motor befor it went in:
232323232%7Ffp9%3A%3A%3Enu%3D323%3B%3E9%3A9%3E559%3EWSNRCG%3D32%3C73%3A396%3A338nu0mrj


Where can I find a filter with the CFM rating. Looked at K&N's website and no luck. I would pefer a cone filter. Any ideas guys?
 

70_Steve

Old Guy
Joined
Dec 13, 2002
Messages
8,317
Nice looking motor!!!

Your question got me thinking, since I just placed an order for a K&N filter for my 351. I did find a page on K&Ns web site that "helps" in filter selection.
http://www.knfilters.com/filter_facts.htm#SELECT

That page includes a formula to determine how many square inches of filter you need for a given size engine at a max RPM. The example given was a Chebby 350 with a 5500 redline. Their formula determined this engine needs 92.4 square inches of filter.

The 350's close enough to my 351, and I just bought a RU-3620 oval filter. At the time, I selected it based on the "bigger is better" principal. I did the calculations on this filter and came up with 134 square inches. So... I should be good!!!
 
Top