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I have just returned from an appointment with K&N R&D today. They have recently delveloped an induction kit for the RS4 and we wondered whether it would offer similar gains on S4 (RS4 gains were around 8hp)

So they tested my car which is stock, engine-wise, apart from running a K&N panel filter instead of the nasty solid cardboard stock one. I had got some improvement in torque, general "pick-up" and sound but these had not been measured. Anyway, the car measured around 150hp (NB: HP not BHP) and 410ftlb on the stock run, then they whacked out the air box and attached the filter cone they developed for the RS4 onto my MAS and tested it. How about 18hp and 40ftlb more? Oh yes God knows how many brake horse power that makes but i can tell you all that on the way home it was a different car. As the torque and power print-out depicted, there is significantly (about, what, 10%) more power throughtout the whole range and a lovely sound. I suggest that this is the best £90ish you could spend on your S4. Hope this helps, Richard Utting

Is this available now? Is it a cone filter or some enclosed cylinderical type?

The rs4 one is out, i believe. And the S4 one designed today won't be far behind, i wouldn't have thought (as it is identical) It is their 57i induction kit - silicone hose with big conical air filter on the end ATB

Does it come with any heat shielding, as without this you will suffer when underbonnet temperatures rise?

What were they using to measure the cars performance? You appear to be around 40-50 hp down on what a standard car should measure.

There's no heat shielding but they leave the original air feeder in place (the one that goes from under the audi badge in to the engine compartment) The head of the filter is right next to that, so air intake temps aren't bad

WRT power output, they use a new 4 wheel rolling road (ProDrive use the same one, apparently)
Whatever the base figure, what's important are the gains, both on paper and on road. Rest assured, my car's power is just fine thank you

How about 18hp and 40ftlb more?

Unlikely.

Even based on the info in your post, why would it give you 18 bhp on an 265bhp S4 when a 380bhp RS4 is only supposed to give around 8 bhp

I've read lots about the oil soaked air filters playing havoc with the MAF's on Audi's because they are incompatible and cause contamination. Do you have any info on this from K&N?

Early VAG MAF's used to heat themselves on startup and shutdown cycles to burn any contaminants off.
However these are not used in S4's, hence why they are so sensitive to dirt, and oil soaked air filters are
definately not recommended for this very same reason.

The induction system in VAG cars is not the point of restriction, therefore induction kit gains are very unlikely...

And those without heat shields are even more of a joke, imagine the heat soak sat in traffic
on a hot sunny day...

Its all about making money...

What do you mean - UNLIKELY? You think i'm making this up for a giggle? Listen guys. These are the facts for my car. PAnel filter made car smoother, quicker and added a nice noise. Full induction kit made very considerable increases in speed on road. Have run aftermarket filters on four cars over five years and all have been imroved by them and have never had any problems whatsoever.
If you go out and buy this filter from K&N you will see what i mean. If you want to shoot me down, then fine: don't go and buy one. I'm sure you're all terribly clever. I'm through with this forum.

It's your choice to post here or not.

We welcome information posted here but you must accept that this is a public forum and people can ask questions as the wish, within reason - My question was (and still is): If an RS4 gives 8 bhp increase, how did you get 18 bhp with an S4 which had a 'performance' filter fitted before the induction kit was put on.

Show us with before and after plots.

Oil soaked filters are a bad idea on any car with a wire air flow sensor. K&N are a reputable company and I would expect them to tell you this without hessitation.

I've been in this game for a very very long time to know enough about induction kits and the like.
A very good friend of mine is the MD for well known aftermarket filter company.
And some of the tricks they get up to to sell their stuff are unreal.
Even though they know their very own products actually negate performance !

But then, sticking that on the box isnt exactly going to make them millions

You mean my new K&N filter might not actually make a 18hp gain?

The new K&N filter will probably make an 18hp gain if your car is stock, which, I could probably speak for a lot of us, it isn't. Most of us have done something to our cars. This guys car was completely stock and he added this in, of course it will give him that boost in hp. Hey, it's your choice. I'm not saying it won't give you the 18hp boost, but I am a little skeptical. It is a very reasonable amount of money, so it isn't such a big deal.

Having spent a considerable amout of time over the last 3years researching this, I have come to the conclusion (as have many others) that the airfilter/airbox on the S4/RS4 is not the limiting factor and there are little (if any) gains to be had. Try posting on www.audiworld.com and see the responses you get!

For anyone who understands how the ECU controls the S4's engine it will be patently obvious that intake modifications will make no difference to a stock car. I can believe that the intake causes some restriction for an RS4 at peak power, so +8bhp seems possible.