air filter need help

[jaywe30]

hi, i have just got a e30 325i cab 1987, and was after an air filter, does anyone know, which would be the best for the car and where i could pick one up,

many thanks

[Cloggy Saint]

Most would say standard is best.

[GDBN]

Your choices are ... standard BMW paper in the existing box, or K&N panel in the box, K&N induction kit or others such as the ITG kit available in the Zone Shop.
You will hear many different opinions. Induction kit will give you more noise.
Some people swear by the original and other swear by induction kits.

Personally, I have just bought the ITG to replace my K&N. (86,325 cab)

G

[dobbie82]

BMW dealer on a standard car there's no point faffing around with cone filters etc IMO

[jaywe30]

its not standard it has a 2.7 bottom end and a few other bits but i wanna try and give it abit extra bhp and a nice nosie

[Bailey]

ive heard stories of people loosing power because of cone filters sucking in warm air from the engine bay. in my 325i cab, ive kept the original box, and just put a k+n panel filter in.

Hope this helps, Guy.

p.s dobbie82, coz your a BMW dealer, does that mean you can help me identify the two cranks i have layed on my gargage floor at the mo?? My local dealer is giving me the silent treatment lol. Cheers, Guy.

[Brianmoooore]

its not standard it has a 2.7 bottom end and a few other bits but i wanna try and give it abit extra bhp and a nice nosie

If the standard airfilter was restrictive, don't you think that BMW would have given it a better one?

[Incitatus]

its not standard it has a 2.7 bottom end and a few other bits but i wanna try and give it abit extra bhp and a nice nosie

If the standard airfilter was restrictive, don't you think that BMW would have given it a better one?

I think cost may have a factor in that, otherwise the logical progression is that every component on the car is a good as it gets, which they're not.

[kunjani]

its not standard it has a 2.7 bottom end and a few other bits but i wanna try and give it abit extra bhp and a nice nosie

If the standard airfilter was restrictive, don't you think that BMW would have given it a better one?

I think cost may have a factor in that, otherwise the logical progression is that every component on the car is a good as it gets, which they're not.

but how could cost be a factor air filters are dead cheap, i also heard of people losing power on their bm's

[Incitatus]

We're talking about mass production design, development and production costs, where small cost differences over thousands of units make a big difference.

The standard air box is no doubt very good, otherwise they wouldn't have fitted it, but it's no basis to assume they (or someone else) couldn't do better.

[DRIFTBOY]

Induction noise could be a factor here too.
BMWs were supposed to be quiet and refined, a cone filter is not that!
I can understand the hot air argument though.
Maybe a cone filter within a cold air box would be best ?
Hard to say without direct comparison on a dyno me thinks.

[MONSPORT42]

From my own experience I'm not sure that a change of filter or an induction kit make a great deal of difference on their own. When I had my 2.7 conversion and gas-flowed head fitted I thought the engine was a bit 'strangled' and put in an ITG panel filter This didn't make any noticeable difference to performance. I then had the airbox drilled out on the front and non-engine side. This just made it noisier. I then had a zone bigger throttle body fitted and did see a difference in absolute top end power and torque. (see the comparative power curves ror my car in the zone articles on BBTBs) . After doing these mods I found that the AFM itself was strangling the car. I had a MAF conversion and fitted an ITG cone filter. After a remap these mods made a real difference to power and throttle response in every day driving and at max performance on track. In other words, unless you can get more air in all the way through to the combustion chamber you're probably better off sticking to the stock air filter. There have been several tests carried out by zone members and others (some good time ago now) that show that the standard paper filter actually performs better than most induction kits although I believe BTG ones with the carbon box show some sort of improvement.

[M5pilot]

I think we should make my tests a sticky.

I did tests a while ago on air intake temperature and found that a cone filter is fine in the E30 engine bay as long as it's not covered with metal gauze like the K&N's.

This metal gauze has a high specific heat capacity and once warm takes ages to cool down.

The foam used in the ITG filters just doesn't heat up.

I used a cone filter type of ITG and also found that once the car is moving the engine bay temperature in that region is no higher than the outside temperature.

The ITG foam/cone filter has been used by so many Zoners and every single one has come back saying it makes a noticeable difference.

As for those who think the BMW system cannot be improved upon - well, you better open your eyes because it so can.

BMW have strict regulations to stick to especially when it comes to noise. We chose the ITG foam filters as they are not noisy like the the K&N's.

Moving onto the panel filters, I did a before and after dyno test on my E30 M3 with a brand new BMW filter and an ITG panel filter - the results speak for themselves:



Thanks
Sal

[Richy325iTouring]

the engine needs cold air
sticking a cone filter on just draws hot air in unless you can get some kind of cold air box/feed directly to it

[GDBN]

It only sucks in hot air when sitting in traffic ... at any speed above say 30 mph the warm air is drawn out. Who needs max power when sitting in traffic ... apart from getaway drivers?

[GDBN]

If you want a good heat shield then the best option id surely a K&N power blanket and a coolpipe directed at the front ... problem solved.