Inductions kits - What you need to know

Before I start this is all from my personal accounts and are my views and should be taken as so.

Induction Kits - What you need to know

Ok so your looking to improve your cars performance, the easiest way is to improve your cars breathing - This basically means allowing the engine to draw air in to mix with fuel quicker and then get it out quicker once its burnt so the process can start again.

Improving you cars induction (air in) can be done with simple to install units.


The Panel Filter
The first is a simple replacement unit that directly replaces your factory air cleaner unit. These are just the same size unit but in a better material than factory items as all cars are built to 1 a budget 2 made to be quiet and 3 be as kind to the enviroment as possible to not mention give a good fuel return.

Most panel filters claim to give a gain but the jury is out on this one, there could be a single bhp or two to be gained here but if truth be know its probally more to do with better filtration and slightly better air flow.

Prices vary due to brand but you could get one between £30-£50 and come in different material like Foam and Cotton depending on brand




The Open Induction Kit
The next is probally the most fimalir, this unit totally replaces the factory air box setup with a open round filter that increases surface area normally because of its design. These units give a advantage due to them being uncovered and open to the under bonnet enviroment there by allowing them to draw as much air in as they like giving a increased induction note. The draws back goes hand in hand with its advantages - Heat Soak - This where your airfilter draws in warm air from the engine bay and power is lost due to it.

Units can cost as little as £20-£30 for universal or unbranded items which may or maynot have a poorer quality of material (again jury is out on this one). Branded items can cost anywhere between £60 - £100+

Gains have been proven over the years on dynos and can add upto 3bhp or more, dont forget tho a open (any) filter is only as good as its supply of cold air, most branded items you will get a pipe/tube to direct cool air or the kit will use the factory supply that supplied the factory air box




The Shielded Open Induction Kit

With the cons of a open filter some brands supply a heat shield to protect the filter from warm air sources such as manifolds. These can be alittle more expensive than normal items and the jury is out on how good these shield work. Again most will come with a Cold Air Feed to direct cool air into the filter.




Enclosed Filters

The last option is a Enclosed filter which is basically a cone filter in somekind of protective casing. These offer protection from Heat Soak which is a major draw back with the open design. The major draw back with enclosed filters is because they are totally enclosed their only supply of air is through a cold air feed. Unlike a open filter than can directly draw any amount of air it needs but a enclosed filter has draw its supply in from the cold air feed which means that under slow speeds and under hard accelration they can suffer.

This has been backed up on dyno's which cant replicate the onroad situation with air being forced into the system by forward motion of the car.

Gains are hard to agree on as mention cant replicate onroad situations but the theory is sound.

These are generally alot more expensive than a normal or shield open kit with prices starting at £100+ and upwards.




In a Nut Shell

If you want to sum up all of the above it basically fits in to this:

Open = Noise
Enclosed = Performance

There are both pro's and con's for all, budget and application for your car in general are big factors in choosing a filter for you car.

Like i said at the begining this is all my views and should be taken at that.

Hope this was useful

Good brief Tspark!

I am sure someone on alfa156 did a rolling road test on all of them and found that the best gave 1bhp gain over the standard one and not a lot difference in torque.They said the best compromise would be a high flow element in the standard airbox, with the cone in place and the GTA intake pipe.

The standard intakes on Alfa's are not bad at all.

If we was talking the best way of improving the factory system, then a cold air box system like a racecar style system would be best.

This is basically a open cone filter in a large box normally carbo fibre that reflects heat with a good air supply.

Very expensive to fabricate and takes up alot of room. The closest to that setup in the list above is a enclosed system like the BMC/K&N Apollo/Pipercross Viper etc

so would it intstead be worth my while making a hole around 3-5inches in diameter in the side of the airbox & runnin a cold air ram pipe of the same (well... slightly smaller) diameter into it? And THEN getting a high performance panel filter to allow better air flow?

Depends on what you want Rancid TS Boy summed it up nicely in the noise and power, any air induction kit is only any good as par of a system of upgrades.

Induction Kit + High flow exhaust system + remap = a stage 1 type alfa setup

Add in fast road cams and other engineered internals and cost starts ramping up but also the gains are bigger then onto foced induction if you want to.

How deep are your pockets?

If you say you wanted to get a 1.6 147 upto 150 bhp then your better off trading it for a 2.0 as it'll probably be cheper in the long run although in my experience there isn;t much in it between a modified 1.6 and a stock 2.0 Twinny.

The thing is, the standard airbox is not particularly restictive, has a cold air feed (under wheel arch) and is plastic so doesn't suffer from heat soak.

There aint a lot you can do with it to make it any better other than the GTA pipe and Hi flow element IMO.

If you are after good performance per pund you might be better off looking at cams, remaps and exhaust. Then start thinking of gas flowing things.

Also remember that plastic topped TS engine have a tuned intake system, which will not work as well if the cone is removed from the airbox.
The cone is there to reflect negative pressure waves back down the intake and this assists in filling the cylinders, the reason it is cone shaped is so that it works over a wider rev band.

Originally Posted by symonh2000

I am sure someone on alfa156 did a rolling road test on all of them and found that the best gave 1bhp gain over the standard one and not a lot difference in torque.They said the best compromise would be a high flow element in the standard airbox, with the cone in place and the GTA intake pipe.

The standard intakes on Alfa's are not bad at all.

which is the exact setup ive gone for and yes it hasn't made a blind bit of difference but does sound a little nicer.

you can do these kits all you like and fall for the marketing all you like, the truth is they do very little. the inlet manifold is the same and the throttle body is the same what can a fancy £150 air filter do?

save your money and put it toward a re-map.

Originally Posted by symonh2000

The thing is, the standard airbox is not particularly restictive, has a cold air feed (under wheel arch) and is plastic so doesn't suffer from heat soak.

There aint a lot you can do with it to make it any better other than the GTA pipe and Hi flow element IMO.

If you are after good performance per pund you might be better off looking at cams, remaps and exhaust. Then start thinking of gas flowing things.

Also remember that plastic topped TS engine have a tuned intake system, which will not work as well if the cone is removed from the airbox.
The cone is there to reflect negative pressure waves back down the intake and this assists in filling the cylinders, the reason it is cone shaped is so that it works over a wider rev band.

i took the cone out for some stupid reason when i replaced the air filter, it wasn't untill i put it back in that i realised the difference it made! was so flat throughout the revs with it out.

It does make a suprising difference.


When the inlet valves open on the engine they create a depression (Or vacuum) the air from the atmosphere rushes in to fill the cylinders, however due to the length of the inlet manifold some air will still be rushing in. This pressure wave will be reflected by the inlet valve back along the inlet to the cone, which will reflect it back to the inlet valve. If the inlet valve is open at the time the reflected wave arrives it will assist in filling the cylinder. The pressure waves travel at the speed of sound.

The variable intake is there because the faster the engine is running the less time there will for the wave to be reflected back, hence it moves to the shorter position.

Its obviously slightly more complicated that than as the TS has 4 cylinders, and each cylinder has its own set of pressure waves.

Its far too complicated to explain much further but I hope you get the gist of it..

If anyone wants to c0ck up their tuned intake by fitting an aftermarket filter good luck to them..

sorry symonh, but there "tuned" intake can be moddified to suit individual drivers needs as the original design is for a happy medium.

I found that removing the resinator box and fitting a direct replacment filter in the origional box works works well.I will have a play with the intake pipe behind the light at some point, and see if more improvments can be made.Most induction kits IMO do nothing execpt make it sound like your going faster.The BMC is probably the best on the market but at around £180 not worth it.Also if you are going to spend money on induction to get the air in and an exhaust to get the air out, you wont feel the real benefit unless you change the cams as Ghosty mentioned.

Originally Posted by Enzo156

sorry symonh, but there "tuned" intake can be moddified to suit individual drivers needs as the original design is for a happy medium.

I agree, the intake is tuned to give the best torque and power compromise over a wide rev band, you could probably gain a few BHP peak on a tuned engine by removing it and fitting a less restrictive induction kit, but you would loose out elsewhere in the rev range.

If your engine is otherwise pretty standard I don't think you would gain much though, except for more noise.

yes, if you want more bhp, you take from mid range grunt etc etc, the only way to get both is more displacement, blowers, gas that sort of thing or my fav.. webbers

you can change your power graph (on a dyno run) by simply changing the lenght of your inlet tract (which has been talked about on these forums in depth)

on mine I only have changed the breathing via exhaust and inlet but the change is noticable, I have yet to remap to take full advantage also.
I have actually lenghtened my inlet to provide more mid range pull as I rarely drive around on the limiter anymore.

Originally Posted by symonh2000

I am sure someone on alfa156 did a rolling road test on all of them and found that the best gave 1bhp gain over the standard one and not a lot difference in torque.They said the best compromise would be a high flow element in the standard airbox, with the cone in place and the GTA intake pipe.

The standard intakes on Alfa's are not bad at all.

What he said, induction kits in my eyes are just noise for the Japanse car drivers And for them to have any sort of proper effect you should get the cars ecu mapped for every change you make to the intake and exhaust parameters to match the air and fuel accordingly

I tried the open kind and it Killed my MAF ,but i then got a new MAF and opted for the BMC CDA enclosed set up ,noticed better throttle response instantly, even though it was more expensive im happy with it.