K&N filters

ktmrfs wrote:
some years ago an independent lab tested the factory duramax filter vs a large number of aftermarket filter systems including K&N and aftermarket direct replacement filters. This was done on the filter used initally on the duramax. Current duramax engines use a slightly different size and shape OEM filter. Haven't seen tests on the new filter.

The factory duramax filter was better at long term filtering, how much dust it took before restriction went above a certain defined limit, and how little dust made it through the fiter than the other filters including K&N. Often by a significant margin.

The "cost" of this is that the Duramax filter did have slightly more restriction than the aftermarket systems, fractions of a psi. Likewise for airflow for a given pressure drop. IMHO it was not significant.

IIRC the K&N wasn't the worst at letting dust through, there were others worse, but it was no where near as effective as the factory filter. And it took less dust to get to the point of needing cleaning.

How the K&N compares to other OEM filters who knows. But on my duramax's, the OEM is the only filter I wll use.

I remember that test and they did not test the whole filter, only cutouts of the filter media. In many cases, aftermarket intakes have filters with a much larger surface area than the OE. In the case of my truck, the ProGuard-7 filter in my intake has twice as much surface area as the stock filter. Also, the shape of the filter matters as well so only testing cutouts only tell part of the story.