Gill wrote:
> Michael Johnson wrote:
>
>>> Exactly, I don't believe an air filter will change mileage. The auto
>>> makers would be on it and so would the rest of this small world.
>>
>> Ever notice that an engine running with a dirty filter sees a drop in
>> gas mileage? The same principle applies to an OEM filter verses a
>> filter that flows better (i.e. a K&N etc.). There are two things that
>> can happen when air flow through an engine is made more efficient.
>> One is an increase in horsepower and the second is an increase in
>> mileage. Sometimes both can happen simultaneously. If you don't
>> believe me then take your air filter and clog it up and run your car
>> for a tank of gas then put in a new one and see whats happens to your
>> gas mileage and power output. I'll bet the farm that they both will
>> see a substantial increase when a clean filter is installed.
>
> One of these days, the next time I have access to a flow bench at work,
> I may have to do some "all things equal side by side testing" of an OEM
> and K&N type filter. At a normal driving speed air flow.
>
> I must say though, adding the power pipe with a larger K&N than I had
> before, and mounting it in the fender sure helped clear some of the
> black smoke I had coming from the exhaust at WOT.

I don't think there will be much difference on a stock engine. Many
times people will open up the intake side and then do nothing to the
exhaust side. You can have the biggest diameter garden hose in the
world but one kink in the line brings the water flow to a crawl. The
same principle applies to an automobile engine.

My guess is that the claimed 15 hp increase K&N makes is on a car with a
blower, large diameter exhaust etc.