Basic air Intake filter tech.

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Basic air Intake filter tech.

Postby Aaran » Wed Jun 02, 2004 10:44 pm

ok- the first modding question everyone asks , what air filter/induction kit should i buy.

this is going to be a breif look at what is avaliable to you and what gains each kit gives and where.

THE COTTON AIR FILTER:

everyone has seen these types of filter, k&n , apexi, aem etc. these filters are made of a very fine cotton mesh that allows more air to flow through it into the engine - these filters tend to give the best filtration against debris and small particles, the are usaly oiled to help catch dust (excption to the apexi unit which is a dry paper element). the trade off is they usual do not allow a huge air flow over stock - just better, and they will wear out as paper/cotton etc is a bio-digradiable material- they also require cleaning. they give a boomy induction noise.

THE PLASTIC/FOAM FILTER:

As the name suggests these filters are made of plastic or foam type materials, they give a better air flow than paper and better filtration against dust particles entering the engine compared to a stainless filter(but usualy let more in than the paper units), they also do not require cleaning as often as paper elements (if at all) . brands that make these filters are hks, pipercross, etc. some of these filter also require oiling.
These give a boomy but slightly raspy induction noise.

THE STAINLESS STEEL FILTERS:

These are the daddys at air flow, they are made of an extremely fine stainless steel wire mesh (usualy 0.5mm-1mm thick). these deffinatly allow more air to be sucked throught them earlyer, and also never require cleaning as the dirt usualy never sticks to the stainless steel.
the big trade off with these is the filtration they offer, which is not very good at all compared to the cotton or the foam filter.

BE WARNED!!- if you want a stainless filter buy a TOP QUALITY UNIT! i have a blitz sus stainless filter, which cost me £250 knickker - i have seen cheaper alternatiaves around and the mesh is not as fine- quiality is no where near as good, and they RUST!!. my advise is to steer clear from cheap stainless units!.

the noise is awesome on a stainless unit, very boomy at low rpms and give a really agressiave rasping induction note, like a toca touring car! loud!


(side note:ABOUT DUST PARTICLES ENTERING THE ENGINE:)

The articles i have read around the net on my years of web browsing will neither confirm weather dust/very small dirt is damaging to an engine or not. the argument go`s along the lines that it causes the piston sleeves/rings to wear faster and damage the engine, others belive that the dust particles are burnt the instant they enter the combustion chamber. i personaly refuse to comment on either argument but will offer you this advice, make your own mind up with regards to which filter to buy, i have outlined the pros/cones of each element avaliable.
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WHAT STYLE INTAKE SHOULD I BUY?


In this section we will cover the types of induction you have avaliable for your engine.

THE CAI (or aka) THE COLD AIR INDUCTION PIPE/KIT.

The CAI kit is probably the best overall kit(ie:aem,iceman etc), it basicly gives gains all through the power band especially on the mid range section of the power curve. the kit palces the filter completly outside the engine bay and away from all engine heat- thus allowing the car to take in ambient outside air temprature which is good for power as the colder the air is the more dense the air is with oxygen, this benifits the engine because the higer oxygen count means a better cleaner burn in the cumbustion chamber which means more bhp!!

the cai unit excells in mid range power because of the air flow velosity ie: the speed the air travelles down the pipe from the filter to the engine. the cai reaches it best possible air flow velocity between the 3000-5000 rpm mark! this is where alot of the big brand manufactures state their power gains- rougthly around 15bhp!!!. the power curve on a stock b16a2 (thats the 1.6 dohc vtec for the non tekkies out there) surges at this point and r.p.m`s and creates a "hump" of power - then as the air velocitiy slows in the higer rpms the power band returns to normal. thus giving the big mid range gains. almost all companies that make cai`s tune the pipe only as far as the stock rpm limit ie: this kit is suited for engines that do not go higer than 8500rpm!!.(basicly the engine sucks so much air above those rpms the cai becomes suffocated! like breatning hard through a long straw and no longer makes power anymore- more likely to loose bhp above the 8500rpm threshold) these kits gove marginal gains at peak bhp-but alot more at midrange rpms.

Pros of the cai:
Always outside temp air being taken in by the engine.
Extremely good mid range gains on most kits- this is where the car rpms are during normal driving.

Cons of cai`s.
can get dirty very quickly due to the filter being at the front of the car.
Can stall the engine/Distroy the engine if sumeregrd in deep water!!
Not good for going over 8500rpms!


THE SHORT RAM FILTER (open)

this is the oldest style induction kit about, the filter is sat on the end of a pipe that is about 12-16 inches long. This places the filter inside the engine bay and allows the filter to become subject to hotter than normal air. as described above the colder the air the more bhp the engine will make- unfortunatuly being sat inside the engine bay where it is alot hotter than the outside air temp usualy means a loss in bhp.

the kit does have its advantages with it though, the air has a shorter distance to travel from the filter to the engine- basicly more air more quickly ie: better throttle responce, also gives a louder induction noise. the kit usualy gives better peak bhp figures (in the higer rpm bands) than the cai kit, simply because air is avaliable more freely than the cai. (short straw long straw theroy - whats easyer to breath through?) you can limit the ammount of hot air or "heat soak" the filter is subject to with a few simple mods- a filter sheild is a good start, as is a cold air feed from the front of the car- this will not stop it mind- only REDUCE IT.

pros:
cheaper than cai
better peak bhp figures.
better throttle expense
no chance of being submereged in water like the cai.
gets covered in less dirt from the road.

cons:
subject to alot of heat (you can loose loads of bhp on a really hot day- iv head of stock cars loosing around 20bhp!!!)


THE FILTER BOX:

As the name suggests, its a filter encased in a box- like the ITG maxaogen filter or the pipercross viper. these still place the filter inside the engine bay- but they are encolsed in a sealed container (usualy plastic or carbon fibre) and have a feed running to the front of the car. this protects the filter from heat and allows the filter to have the same responce as a std short ram without the heat problem. these give very good peak bhp gains on the car depending on the kit, but only to a certain extent, the air still has to be feed/sucked to the filter through a pipe from the front of the car like a cai kit,- i have yet to see a enclosed filter box on a very high rpm car (ie:9000rpm+) so i cannot comment on how the preform, but in assuming it will not be AS good as a pure short ram system at those high rpms.

pros:
very good peak bhp gains (to an untesed extent....)
eleminate the heat soak problem
still draws ambient cool air from the front of the car.

cons:
very pricey
im not sure how well they preform at very high rpms.
feed has to be posistioned unrestricted (the ammount of people i have seen that have bent the feed 90-odd degrees a few times is unbeliavble- the smoother the bends the better to keep air speed/flow at a maxium)


NOTE ABOUT HEAT:

heat kills bhp simple! the filter might not be exposed to heat but the pipes that run to the throttlebody (engines main intake) can still transmit heat to the air thus causing the air to walm up- always try to cover the pipe in heat resistant material/wraps to stop heat transmitting throught the pipe to the air inside (this will lower the bhp figure)


PLEASE READ:
please do NOT DISTRUBUTE my articles. they are ment for USERS INFO ONLY and as far as i am consirned they are for me + the site( delsol-uk) ONLY. if you distribute i will ban your ass!!! ;)

DISCLAMIER:
DelSol UK is run by enthusiasts for enthusiasts on a not-for profit basis - any information on this forum is given in good faith but without liability to the site(delsol-uk) or the articles authour. Errors and omissions excepted .Also we WILL NOT BE held responsiable for any mis-information given. Any how-to guides you read are carried out at YOUR OWN RISK as any resulting damage caused to your car etc is your own responsibilty.








cheers all,

Aaran (hwo`s hands are acheing from typing so much!)

ps: pics to follow in thread.
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Aaran
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