Subject: Re: [Shop-talk] Performance Air Cleaners

From: John Innis <[email-masked]>
Date: Wed, 5 Nov 2014 19:48:30 -0600

Not sure about the bimmer, but I know that on some of the GM cars I have
owned the "cold air" performance filter had advantages and disadvantages.
It did seem to improve performance, but only at the very top end.  It also
made the car louder.  A lot louder.  So much so that with a stock exhaust,
the intake was louder than the exhaust at idle and it just roared at full
throttle.  The lack of a proper filter box also made the car susceptible to
splashes in the very wet.  So bad that running through a puddle killed the
motor on one occasion.  The filter got so wet I had to dry it out to get
the car running again.  For my situation, the performance filter in the
special "cold air intake kit" was not worth the tradeoffs.  I DO run a K&N
filter in the stock box on several of my vehicles, and have been happy with
them, but I have not notice any measurable gain in performance.  I just
prefer to be able to clean and service my air filters.

On Wed, Nov 5, 2014 at 6:13 PM, Jim Stone <[email-masked]> wrote:

> I have been watching old episodes of Wheeler Dealers lately and the last
> two I
> saw were about an MX-5/Miata and BMW 3 Series.  In both cases, one of the
> first things Edd did was replace the stock air cleaner assembly with a
> performance air filter.  According to Edd, it is all good: increased
> horsepower, better sound, etc.  However, I have to believe that the
> contraption he is replacing (filter box, filter, hoses, etc.) costs the
> manufacturers more than than performance filters would.  If the KN options
> (I
> think that is what Edd is using) are so good and increase horsepower, why
> wouldn t the manufacturers - particularly BMW - put them in to begin with?
>
> Just curious.  And thinking about my 2000 3-Series.
> _______________________________________________
>
> [email-masked]
> Donate: http://www.team.net/donate.html
> Suggested annual donation  $12.96
> Archive: http://www.team.net/archive
> Forums: http://www.team.net/forums
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/shop-talk/[email-masked]
>
>

-- 
=================================
= Never offend people with style when you   =
= can offend with substance --- Sam Brown  =
=================================
_______________________________________________

[email-masked]
Archive: http://www.team.net/archive

---

From: John Miller <[email-masked]>
Date: Wed, 05 Nov 2014 21:25:49 -0800

On 11/5/2014 4:13 PM, Jim Stone wrote:
> I have been watching old episodes of Wheeler Dealers lately and the last two I
> manufacturers more than than performance filters would.  If the KN options (I
> wouldnt the manufacturers - particularly BMW - put them in to begin with?

Well, substantially increased maintenance requirements and certain 
finicky incompatibilities with some engine controls, increased noise, 
potentially reduced engine life depending on the filter material, etc.

And they only offer any sort of performance improvement

The K&N and similar oiled-foam filter elements are the subject of 
religious wars, some feel that they do a poor job of trapping smaller 
contaminants, they certainly have less surface area than a typical 
OE-type pleated paper filter and will clog up faster.

The filter itself is expensive compared to a decent paper filter, and 
while some folks do just toss them every year they're intended to be 
serviceable through cleaning with soap and water and re-oiling.  In a 
modern engine equipped with a hot-wire mass-airflow sensor, failure to 
get ALL the excess oil off the filter after re-oiling can result in 
contamination of the MAF, something which many automakers have gotten 
quite good at detecting (and it will NOT be covered under warranty.)

The filter itself is rarely an obstruction in modern intake design; the 
design of the airbox plumbing can be, though that's usually for 
noise/sound control, keeping the snorkel high enough that it doesn't 
suck in water from puddles, etc.

Personal opinion: they're not snake oil but they're rarely a significant 
improvement.  I have them on a couple cars, but they have to be 
maintained.  Our 195K-mile '98 540i has had a Dinan intake with such a 
filter for almost all its life.

You also have to look out for the various quirks of aftermarket intake 
systems - if the intake is not sealed off from hot engine compartment 
air you are probably losing power from it, and in the case of our 540i 
the filter is located low on the right side, and there have been cases 
of cars with that setup sucking enough water to hydrolock the engine. 
Certainly that's never happened to us, but I did manage to suck enough 
spray from a puddle along a curb to destroy a MAF once...

Was once on a tour of the Dinan facility, eight or nine years ago?  They 
were doing some work on an E60 545i or 550i and Steve Dinan noted that 
the air filter element was actually two separate units - the usual paper 
filter, with an activated-charcoal filter underneath it to help the car 
pass the EPA hot-soak evaporative-emissions test (prevent vapors from 
any drops of fuel that might leak out of the injectors from making their 
way back through the intake passage.)

He said just removing the charcoal filter was worth 15HP.

John.

[email-masked]