My old filter ripped I need a new k&n but cannot fit the 6" height so I found

K&n part # RU3700

3" flange, 5" base filter diameter, 4" element height, 4.625" top diameter.

It's a bit smaller but would fit well. Wondering tho if that's too small or any other options anyone has found let me know

 

Call K&N they can calculate the flow rate of each filter.

 

What flow rate would a 400hp require

 

~600 CFM. I have a small filter like that on my setup and taking it off on the dyno netted no change in power at 460whp

 

Beautiful I have it ordered. The roads I ride on are muddy hahaha so totally unacceptable to have none. For that edge tho if needed I'd remove it at the track.

Almost time to tune again... Hoping for the best cause cars that come off this dyno make real power I didn't want to be limited cause of a filter

 

I dug this up from an old email I had with an engineer at K&N in 2006.
*WARNING MATH ALERT*

To determine the maximum volume of air your engine will use, take the displacement in cubic inches and multiply by the maximum RPM you operate the engine at. If the engine is supercharged or turbocharged, divide the pounds of boost by 14.7, add 1 to this answer, and multiply this value by the CIDxRPM value. Divide by 3,456 for a 4 stroke engine. This will calculate the maximum airflow required by the engine.


Cubic Inch x Max RPM x (B)
------------------------------ = CFM
3,456


psi
---- + 1 = B
14.7


To determine what volume of air a given filter is capable of flowing, multiply the diameter of the filter by its height, multiply by pi (3.14), and multiply by 6. If the filter is a tapered cone (different diameters at each end), add the diameter from the top and base together and divide by two for an average diameter. Here are some examples:


Round Straight filter:
dia. x height x 3.14 x 6 = CFM

Round Tapered Filter:
(dia. base + dia. top)
---------------------------- x height x 3.14 x 6 = CFM
2

For best performance, select an air filter that flows more air than your engine requires at maximum operating RPM.

 

OR not being lazy and actually look on the manufacturer's website...

http://www.knfilters.com/filter_facts.htm

Filter Selection tab...

 

agree.

OP, you can probably find an exact replacement for the one you have. just get the dimensions and find the corresponding part on k&n's site
http://www.knfilters.com/search/univcone.aspx

 

Welp this is the response I got. Hoping for the best anyway


Thank you for contacting K&N. Based on the surface area of the filter, RU-3700, the flow rate would be approximately 362 CFM at 1.5 inches of water. If you have any other questions please feel free to contact us at 1 800 858 3333.


Thoughts? Like the 1/4 space I am not usin would get it to 600
I doubt that.

I will also update and remove on a dyno pull

 

I tried to understand what 1.5 inches of water I am currently 246ft above sea level

 

Its just a measure of static pressure, commonly used when talking about airflow and HVAC stuff.

The turbo will pull way more vacuum then that so Im sure the filter will work. whether its filtration is rated for that much is a different story.