My oldest stepson wants to replace his 1995 Pontiac Firebird Formula's air
filter with a K&N. Would this make the car get better or worse gas mileage?
It seems as though the air-gas ratio would increase giving it more power but
worse gas mileage. Maybe I'm wrong. Since it would allow the engine to
breath better maybe this would improve the gas mileage.
At any rate, I'd like to know the truth about this before he drops any cash
on the K&N. If it's going to make the car use even more gas than it already
does, he'll probably drop the idea altogether.
Extremely doubtful that he would see a gain or loss in power or mileage. Try
this test. Take the air filter completely out and drive it. It won't run any
better or worse unless your current air filter is clogged and restrictive.
An air filter has nothing to do with fuel economy. The K&N will help
the car to breath better, thus allowing it to perform better. Not to
mention with cleaning, you will save on the cost of paper filters.
On a stock car, you might get .5 (1/2 of a HP) power increase at
wide open throttle. That little amount of increased air flow will not
cause the injectors to go richer then normal.
I threw a K&N on my 01 Trans Am. Fuel economy change - negligible. (I
track all my fuel mileage in a spreadsheet.) Performance - maybe a 1/2
tenth at the quarter mile. (13.11 NA, 12.18 with 100 shot... over 50
passes at the strip.)
Why spend the $50? Because a paper element was $25 and I was replacing
it every year... so it's cheaper in the long run for a K&N for this car.
(Wife's Beretta... not so - $50 for the K&N, $5 for the paper one.)
You car pretty much gets all the air it needs at normal throttle opening
with the stock filter set up. Anything you do to increase air flow at
less than full throttle is a waste, because the only real restriction
is the throttle plate. Once you open the throttle all the way, then the
K&N may help. But only if it really passes more air than the paper filter,
and the throttle body is capable of passing that extra air into the engine.
One side effect of the K&N is that because it does allow more air into
the engine, it also allows more dirt. Which defeats the purpose of the
"They that can give up essential liberty to obtain a little temporary
Different air cleaners have different amounts of resistance to airflow. If
a K&N has less resistance (debatable) it can accomplish this a number of
different ways. One way is making the filter media more permeable - which
will let in more dirt. But, another way is if the permability of the media
the same, you can increase the area of it - ie: more pleats - which also
reduces air resistance of the media. You can also use media that
is designed differently. (probably more expensive than plain paper, of
In short, filters and their design are considerably more complicated than
your making them out to be, and thus your rule of thumb is pretty useless.
Did you bother to even read my post?
Dick is claiming the K&N lets in more dirt. I have no argument with that
I am not even talking about that.
What I am saying is that the rule of thumb the other respondent posted -
is that if the filter lets in more air it lets in more dirt - is a bunch of
There is nothing in Dick's study that contradicts this or even addresses
As I said, better filter media could be designed that would allow greater
and remove just as much dirt. If you believe Dick's study, then the K&N
doesen't use better filter media. But the K&N isn't the reference standard
filters. Just because this hypothetical better filter media might cost 20
of paper, doesen't mean it can't be designed.
I would invite you to look over the filter designs used in the Space Shuttle
other esoteric installations where cost is not an issue. I would bet that
find that these filters do indeed have much better airflow than paper, and
even more dirt, with a smaller media area. And undoubtedly they will cost
times that of paper, knowing the US Government. ;-)
A fact often overlooked by most people: The media it's self (cotton
gauze type) is not only a better Media for filtration. The fact that it
is a WET type filter also has something to do with filtration. This is
Paper Media filters are a low cost item. They let thru an "acceptable"
around of dirt by Automobile Manufacture Standards. Washable, Reusable,
Oiled Cloth Gauze type filters cost more to produce. Since the lower cost
item good enough to keep an engine going 300K+, vehicle makers see no
reason to use a higher maintenance, higher cost item. Which does make
perfect economical since. They leave it to the consumer to choose the
higher cost, and install it them self's. This is an item that will not
void any US Automakers warrantee.
People also forget that such filters when used in high dust area's
also require a Course Media filter. Else wise larger partials will clog
the finer, oil impregnated media. Most Pre-Filters for the filers are
made from Large cell foam rubber. The cell is the void, or air gap. Some
small engines (Industrial & Lawn mowers) only use a Mid Size Cell Foam
Rubber filter. Most of those are supposed to be oil coated. They are
washable. The service life is anywhere from 2 years to 15 years. Yet they
must be cleaned as part of preventative maintenance ever 25 to 500 hours
(depending, some are recommend for 3 times what they should go).
Very few people do P-M on their vehicles, let alone equipment. They
just run them till something breaks, wears out, or fails.
Another thing people often forget is High End air filters for
automobile HVAC, Hospital HVAC, Building HVAC, and Residential HVAC
are often made from woven fine media cloth fibers. Some have other fibers
both natural and synthetic added to them to increase performance in one
aspect or another. Where as the standard low end filters for these
application are either woven fiberglass strands, or pleated paper
Do you have a link to that? A TSB?
I have a K&N on my TA - it's out of warranty, but I'm curious...
(Oh, and I put the K&N on because it's cheaper than throwing out a paper
filter every year - in my case a K&N was only the price of two paper
Automatic Transmission Shift, Engine Drivability Concerns or
Service Engine Soon (SES) Light On as a Result of the Installation of an
Aftermarket Reusable, Excessively Oiled Air Filter
TSB #04-07-30-013 - (03/05/2004)
Ok, is it possible to get the full text of the TSB?
Here's the TSB listings for my car (01 Firebird TA, LS1 V8)
This TSB is NOT listed in there - which is interesting because I'd be
willing to bet the F-Body has one of the highest percentage of owner
modifications that violate the warranty.... (myself included.)
I've had the MIL come on for O2 failure - but in my case I blame the
nitrous instead of the K&N. Resetting the light worked and my new
AutoTap sits unused...
Sure...here it is:
Info - Automatic Transmission Shift, Engine Driveability Concerns or Service
Engine Soon (SES) Light On as a Result of the Installation of an Aftermarket
Reusable, Excessively Oiled Air Filter #04-07-30-013 - (Mar 5, 2004)
Automatic Transmission Shift, Engine Driveability Concerns or Service Engine
Soon (SES) Light On as a Result of the Installation of an Aftermarket
Reusable, Excessively Oiled Air Filter
2004 and Prior Cars and Light Duty Trucks
2003-2004 HUMMER H2
DON'T DO THIS
First, Inspect the vehicle for a reusable aftermarket excessively
oiled air filter
DO NOT repair under warranty if concerns result from the use of a
reusable aftermarket oiled air filter.
The installation of an aftermarket reusable, oiled air filter may result in:
a.. Service Engine Soon (SES) Light On
b.. Transmission shift concerns, slipping and damaged clutch(es) or
c.. Engine driveability concerns, poor acceleration from a stop, limited
engine RPM range
The oil that is used on these air filter elements may be transferred onto
the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a
result, the Grams per Second (GPS) signal from the MAF may be low and any or
all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for
the presence of an aftermarket reusable, excessively oiled air filter. The
MAF, GPS reading should be compared to a like vehicle with a OEM air box and
filter under the same driving conditions to verify the concern.
Transmission or engine driveability concerns that are the result of the
installation of an aftermarket reusable, excessively oiled air filter are
not considered to be warrantable repair items.
ok, I understand the idea that an over-oiled filter is bad, but how
exactly does that kill an automatic transmission? Don't give me the "GM
line" - someone explain how the oil in the intake tract will cause the
clutches in the tranny to slip...
(who didn't over-oil his air filter. ;)
The MAF sensor gets coated in oil and that alters the signal (makes it a
lower frequency or something) that's sent to the PCM. The altered signal
changes the line pressure to a different value (lower I believe) and can
I notice this bulletin REPEATEDLY uses the modifier "excessively
oiled". I think if GM could really get by with denying warranty
claims very easy on this, they would simply say "use of an oiled
filter." That's just a hunch though.
Anyway, another way to look at this is to say that use of a properly
oiled after market oiling type filter, should not cause such concerns
and is not cause to deny a warranty claim.
Which leads me to believe that when cleaning and re-oiling such
filters, everything can turn out A-OK if care is taken to oil
On Thu, 29 Jul 2004 22:49:02 GMT, "shiden_Kai"
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