Air Filter Study, Flow Rate and Filtration Options

[pvollma]

I found the link to this study on a Lincoln Town Car forum:

Air Filter Comparison Study

While it was done using air filters for a GM Truck, the conclusions are interesting:

1. choosing a filter type or style for ‘more flow’ for either performance or fuel mileage is useless, as they all flow about the same

2. there is a wide variance in the ability to filter contaminants; the best was an unoiled synthetic fiber passing less than 1% of the contaminants introduced, while the worst was an oiled foam allowing 40% to pass. To bring in some 914 relevance, the K&N was second-worst, passing 35%.

I make no claim that this applies directly to our 914s, but I found it interesting since I've always used K&N filters on my performance cars.

[Tom_T]

That study or test is not surprising, & there are a few others out there coming to the same conclusions.

My long time 914 Porsche Mechanic (he trained on them in `69) had said the same thing about K&N & the other suppusedly "higher flow" air filters - they don't add appreciably more air flow, but do add significantly larger particulates into the engine & systems due to the more porous filter material.

He said flat out not to use them - & instead use a very good quality OEM 914 filter (or whatever make/model it is).
He said in his Austrian accent: "I haf my vays to get performance out off deze engines!" (IMG:style_emoticons/default/shades.gif)

The other thing that K&N tries to hook you on is that they're "reusable filters" - but per Hans: "Der iss no vay dat you can get dat filter completely clean!"

I've been taking my 914 & other cars to Hans since 1975, & he PPI'ed & rejected 2 dozen 914s in `75, before I got his blessing on the 73 2L I got & still have. So I trust him implicitly!

(IMG:style_emoticons/default/beerchug.gif)
Tom
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