| Filtre
de aer
There seems to be 100's of different types of air filter
available for whatever you drive varying from replacement air filters
which take the place of the factory one to direct air induction kits
as pictured above, but what do they do and how effective are they ?
What they actually
do ? Well they clean the air before it goes into the
engine, the theory is that the more cold air you can get into the engine
the more power it will produce as long as the fueling is adequately
proportioned. It follows then that if you replace the standard air filter
with one that will allow more air to flow through it you can gain power,
don't expect miracles though ! Replacement filters - We'll start with
replacement filters then, they come in all different flavours but will
all look basically the same in shape as each other for your particular
car, they replace the standard one in the standard air filter box and
have the advantage that they can usually be cleaned using a special
solution giving you a re-usable filter that can outlast the engine.
They will normally give you a little bit more induction noise and a
couple of bhp, yes that's right maybe 2 bhp if you are lucky. People
that tell you more can be had are talking shite, the main restriction
here is the standard air cleaning system, remember this air filter will
only have the same amount of air being fed to it as the standard one.
Induction kits - K&N 57I, Ram-Air, Piper etc are all familiar direct
air induction systems that can be bought for your car and will require
a of fitting. I have a K&N 57i kit fitted to my Pug 309 and although
it's difficult to measure the performance difference I feel that there
are several advantages to be gained by fitting such a kit as follows
: Looks - The filter looks impressive under the bonnet, in the case
of the K&N there are many components removed such as the air box
for the standard air filter and the rubber ducts that feed the air box.
This makes for a cleaner look under the bonnet and the air filter itself
looks the
business.
Power - There
is some extra brake horsepower to be had from this type of filter particularl
if complimented by other mods that help the engine breathe or the engine
requires more air. These would include performance exhaust systems and
gas flowed heads. Just how much can be gained is difficult to establish
because measuring the power output of the engine is best done on a dyno
or rolling road, in these circumstances the car or engine is stationary
which means that the usual abundant supply of cool air is not available
so rolling road results may be disappointing. There is a few bhp to
be had here though in most cases. Re-useable - Again these filters can
be cleaned and re-used like most replacement high performance filters
which means that the filter theoretically need not be ever replaced
which in the long term has to save money. I would warn that it is worth
using the recommended manufacturer cleaning materials and oil because
this prolongs the life of the filter.
Induction noise
- This now isn't as subtle as the replacement filter, you can actually
hear your engine breathing ! I love it but appreciate that it may not
be everyones desire, coupled with a good aftermarket exhaust system
to maximise engine throughput results in some reasonable power gains
for not a huge amout of cash. As far as I know the fuel economy of the
car remains fairly unaffected. The mixture must be adjusted though on
some filters because the extra air being drawn into the engine would
lean out the mixture if the fuelling wasn't increased accordingly and
could also affect emissions.
The kit - Usually
consists of little more than the filter, a fitting pipe to attach it
to the air-flow metering unit and maybe a retaining bracket and cold
air feed pipe if required. The K&N 57i kit i used is a DIY fit but
a word of warning - make sure you purchase the exact kit for your car
! Buying a Pug 205 gti one like i did caused me real problems. Most
cars use the same idea though so fitment time really depends on the
access you have in the engine bay. If there is no kit for you car it's
possible to buy these cone filters in different bore sizes and you could
make your own induction kit, the idea is that the cone filter can allow
a more direct path for the air flow into the engine and cold air pipes/ducts
canm be used to feed more air to that part of the engine bay.
On nearly all these kits the standard
air cleaner box will need to be removed, once this is done some kits
attach the new filter to the air feed pipe that connects to the standard
air box, in the case of the K&N the air box and all the feed pipes
are removed, the battery is then moved back on it's tray and a new pipe
is provided that fits to the throttle body. The air flow meter is then
turned through 90 degrees and fits onto that
bracket I mentioned earlier that is provided. The new air filter is
then fitted directly behind the passenger side headlight. A cold air
pipe is then fed from the front valance up to the filter, on the 309
i simply
moved the power steering reservoir around and made a bracket to attach
it to the battery, there was no need to remove or chop any of it's pipes.
That's all there was to it though. The mixture is best adjusted by a
garage who can use a gas analyser for better results. I know it all
sounds a bit of a nightmare but the results ARE worth it and full instructions
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