hey guys,

at the minute I have only got a performance air filter, until i get one of the focus inductions kits that I've seen people raving about on here. As i don't have the air intake pipes etc it's connected to the factory air box for now but was just wondering if the position of the filter was important.

There's 2 position i can have it and i'll add pictures to show you.

please help I'm a bit of a newbie at this

thanks guys

thats the first position which is directly on to the air box


this is attached to the air box via the intake pipe

sorry did it wrong

The cooler the air feed the better. You're 1st position will be picking up warm air from the radiator which is not ideal. The 2nd position is better as long as there is no air pocket / starvation due to trubulent airflow around and under the car.

For winter running you may find that position 1 is actually better and for summer position 2.

Experiment is what I would suggest. You can also do some crude performance testing with a stop watch.

Drive in 3rd gear at say 1500 rpm then floor the throttle and time how long it takes to get to 5000 or 6000rpm. Use a quiet flat round and take readings in both directions.

^^ Sound advice and pretty much what I was going to say

Both solutions will result in LESS horsepower and ( much) more noise than the original airfilter and box..specialy when the engine warms up.
The ONLY proper way is to install the "performance(??)" filter outside the engine bay, away from engine heat, but at colder outside temps, you will run in problems again....
It took the factory a lot of testing and re- designing of the airbox to get maximum result, there's no way you can do it better.

sorry if I'm being a bit stupid but if the design of the air box is really good, and everything is pretty much in the same position just with a filter that is meant to be less restrictive to air flow would this not help?

sorry if the questions are obvious or stupid but I'm just trying to learn

Easy, fuel needs oxygen to burn, warm/ hot air contains less oxygen, so les fuel to burn, meaning less horsepower.
That's why the original airbox will ALWAYS get air from outside the hot engine bay.
Those so called "performance" filters that will take the place of the original airbox will suck in only hot air, so they are better called "No performance filters", waste of money if you ask me....!!

I'd agree with you to some extent Peter - in the first position, or in the case of the K&N filters which just sit on top of the throttle body - complete crap! But it sounds like you're tarring all performance air filtration systems with the same brush - properly piped to allow it to pull in cold air in larger volumes than the original airbox will be a good thing, surely?

Maybe, but one needs very expensive equipment to measure the (small) differences, if all....
Remember all "performance" gains less then about 5 HP isn't noticeable at all.
Want a free performance gain....??
Raise the airpressure in your tires....!!!!

so if the existing air box gets only cold air, then having the filter attached to the end of the intake pipe which in its original position, would, in theory only get cold air also, but at a less restricted flow rate therefore slightly increasing horsepower?

As long as you've taken the original filter out of the airbox before attaching that one, I would tend to agree

If you insist: K&N has special panel filters to replace the original, paper filter, so the airbox can stay in place.

the air box is only staying on as a means of connecting the filter and also having the breather pipe connected until I get some proper piping for it, I was going to get one of these focus kits http://cgi.ebay.co.uk/FORD-FOCUS-1-8-2-0-ZETEC-00-04-AIR-INDUCTION-FILTER-KIT_W0QQitemZ350326063273QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item51910f80a9#ht_843wt_958 that people have been talking about, but thats seems to sit quite high in the engine bay so wouldnt that have the problem of taking warmer air into the engine?

Yes.
Keep airfilters away from the enginebay, no matter where it's position will be..!

Peter Pick-Up said:

Yes.
Keep airfilters away from the enginebay, no matter where it's position will be..!

Click to expand...

Agree, but....

The air pickup/intakes vary from car to car. A very common place is in the engine bay but from behind the headlight. This represents a cost compromise by the maker. The additional plumbing/ducting to take air from other places is expensive. Another common place is down under the front bumper.

Decent free flow filters, like K&N do exist and can make a noticable difference DEPENDING on application and installation. These filters are twice the cost to the car manufacturer so they avaid them at all cost. It is cheaper for them to fit much larger paper filters which is exactly what they do.

The whole process is a design and cost compromise which can, in some cases, be improved up by people willing to buy expensive filters and piping to create an alternative setup.

Something end users CAN'T easily work around is the ever more common "resonator" intake tuning that goes on in the original design.

s130 said:

Something end users CAN'T easily work around is the ever more common "resonator" intake tuning that goes on in the original design.

Click to expand...

Can you expand on that a bit? Am not really sure what that means

Start here: [ame]http://en.wikipedia.org/wiki/Cold_air_intake[/ame]

Apart from noise cancellation I believe that a well designed resonator system helps low air speed (rpm) performance issues in that the intake airflow is smoothed from intermittent pulses to a more steady and laminer air flow with less eddies.

I think the holy grail of engine tuning is to get maximum power, maximum torque, maximum driveabilty, maximum fuel economy .......etc.

Most (all?) car manufacturers try to find the best compromise for the type of vehicle they are producing. Even, for example, a Ferrari 355 has a race version where the compromises are thrown away and a focus is made on whatever there think will make the car go faster under race conditions.

For example: High lift cams provide maximum power and torque but only at high RPM. Some of these engines idle at 2000+ rpm and are totally gutless till 4000+ rpm and delivering top performance at 6000+ rpm.

Trust me you would not want to drive this type of car as a road, even fast road car.

With all this in mind there is however a small window where modest improvements can be made but with some sacrifice.

e.g. a performance air filter (correctly installed) will possibly give a modest (less than 10%, typically 2% to 5%) increase in engine top end power but will be noisier. Boy Racers (tounge in cheek) will go for 1% and will love the increased noise even more. Intake/exhaust noise = powerfull performance car..........