6.4 Air filter Pre filter in Lid?

[Shawn Zeitner]

Seeing this reminded me to test this out. So a little background of myself. I have ported cylinder heads for 20+ years now and owned a Dyno when I had my own shop. This is not the best test but gives some info about the filter system . I bought an extra air box top so I could do an A to B comparison of air filters. My Flow bench will not flow enough air to give an CFM rating on an air filter. My bench needs to see 2inchs of pressure to give A CFM number. I like to play with this kind of stuff and there is always something to find and is learn about. The factory air intake is a good design in my opinion. Cold air and ample flow. A gasoline engine is air starved so more air is usual a power gain. When the air is controlled by a computer you not see a change. ie drive by wire. On my truck I removed the carbon filter and run run the Larger Cummins filter. Also changer all the edges on the in let of the air box lid (OCD ). This was done as a comparison between between filters and changes amongst them. And I like messing with stuff.

So to test an open hole of 3.54 inch diameter pressure (this size was chosen as it will seal the best to the air box top) 1.19 inch of pressure drop.
The air box lid with the carbon filter 1.45 inch of pressure drop.
The air box with the carbon filter removed. 1.21 inch of pressure drop
OEM filter 57008652AA with carbon filter 2.30 inches of pressure drop. (397cfm)
OEM filter 57008652AA with carbon filter removed. 1.75 inches of pressure drop
OEM filter 6851754AA Cummins filter with carbon filter. 1.81 inches of pressure drop.
OEM filter 6851754AA with carbon filter removed. 1.52 inches of pressure drop.

So is it better to leave the choral filter in or remove it?

 

[oppizzippo]

So is it better to leave the choral filter in or remove it?

it's better, how much better??? Not very much, but makes me happy it's gone.

 

[Dewey]

So is it better to leave the choral filter in or remove it?

Power will be better as the engine will get easier air. Its hard to tell the throttle movement is controlled by the computer. I run without the charcoal filter and a Diesel air filer.

The charcoal filter is an emissions thing to help with off gassing. I Found filter top from eBay for 40$ to test with I think form 2019 or 2020. This way I could but it back if I needed or wanted too.