Theo,
It's interesting to also compare the pressure drop to the flow needed by
engine. Just starting with round numbers, a 300 cu. in. engine turning
6,000 rpm would pull in 521 cu. ft. per minute; that's IF it had 100%
volumetric efficiency, which it never does without a blower or turbo. I'm
not sure how much to knock off for a typical or even hot rodded engine, but
somewhere between 80% and 90% I would think. For 85% efficiency, that's 443
cu. ft. per minute. I think these numbers just support your contention that
the filter per se isn't the problem. It's probably just this line of
thinking that led to velocity stacks and the like.
Brgds,
Bob
At 10:10 PM 4/25/00 -0600, Theo Smit wrote:
>Hi all (all of you that haven't abandoned this discussion)
>
>I was reading the K&N website info some more and they mention that they
>compute the rated flow capability of their filters based on 1.5" H2O
>pressure drop. What does that mean in the big scheme of things? If you
>run the filter at double the rated flow (like Larry), you will get four
>times the pressure drop - six inches of water. That is equivalent to
>less than half an inch of mercury, which is about the difference between
>a cool spring morning and a hot afternoon with a thunderstorm brewing.
>
>The bottom line is, the air filter element itself ain't making 20
>horsepower difference. What would be interesting is to run the engine on
>a dyno, with only the air cleaner housing in place - top and bottom
>(using some kind of spacer), no element, and compare that to the same
>thing with the element. I think the lion's share of the loss will be due
>to the proximity of the air cleaner top to the carb throat.
>
>Regards,
>Theo
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