K&N cold air induction + fogged

[Rob-with-Rosie]

Hi all. Has anyone fitted a K&N cold air induction kit and added a heat shield "box" around the filter to keep the heat out, but also fed the box with a wide diameter pipe in the same way that a "fogged" article suggested? Just that I have read various discussions on one or the other but haven't seen anything about doing both? Also there seems to be concern over the K&N getting oil on the MAF and causing problems.

Any thoughts on this would be appreciated

 

[GazHyde]

If you fit a cone filter you need to shield it, so a heat shield is a no brainer in the discussion. As to providing an additional air feed, then thats just down to what you want to do. The more cool air you can get to the cone filter the better, but there is a reasonable amount of air flow which comes through the gap by the headlight.

Personally when I fit a cone filter I'm going to see how it performs, then add an additional feed if I feel it needs it.

 

[zedonist]

I disagree on the heat shield on a NA car and in particular the M44, the heat build up is not that great if any, especially if you have cold air supply. The car also has an air temp sensor so that it can maintain the fuel air ratio, and the density of the air is not going to change that much in 10 degrees, so really it does not matter. The heat shield will more than likely suffocate the filter.

From my experience the K&N made the car breathe better, but felt it was restricted, later backed up by some good test data, based on this swapped out to the the largest piper cross that would fit, and the car is miles better, and is better than the fogged air box route (tried that also).

 

[littlefeller]

as regards to the hot air idea, i struggle to understand this, a 2l engine will use 3000 litres of air at 3000rpm @ 6000 its using 100 litres every second (thats 50 bottles the size of cola bottles at 2l, so how much air can there be under the bonnet. Ok a drop in say 10 deg might be measurable but would still be very small (although it would be free hp) but could the air under the bonnet really raise by that much considering how much your using?. maybe im missing something here.

 

[Kev Bennett]

Advice required please as I have a standard air filter set up on my 2.8 ,what advantages would I see if I where to change to a cone type and which one would you recommend and where to purchase from any advice gratefully received.Kev.

 

[smiffy]

a couple of years ago, a customer of mine had a boat built with larger than average engines. They found on seatrials that the engines wouldn't rev properly and give the required speed. By chance, whilst trying to solve the problem, someone tried to open an engine hatch while the engines were running flat out and couldn't. Turned out the engine bay vents were too small, and the engines were creating a vacuum in the engine bays! This was sucking the hatches tight to their seals and strangling the engines! Opened the hatches at idle, opened the engines up and they went through the redlines! Bigger vents fitted, problem solved.

It would be interesting to fit a vacuum gauge into the engine bay and just see if a vacuum is pulled.

Inlet Air temp should be available via OBD.

 

[andyglym]

Put a K&N Panel Filter in mine, first drive out (whilst not earth shattering I hasten to add) there was defo a differance albeit neglageable and my exhaust acquired a "bark" post 3000rpm that it never had. Pretty sure I haven't imagined it.

 

[Rha]

Hi all. Has anyone fitted a K&N cold air induction kit and added a heat shield "box" around the filter to keep the heat out, but also fed the box with a wide diameter pipe in the same way that a "fogged" article suggested? Just that I have read various discussions on one or the other but haven't seen anything about doing both? Also there seems to be concern over the K&N getting oil on the MAF and causing problems.

Any thoughts on this would be appreciated

Hi Rob, I've tried various ways to fog differant cars and must admit it's not an exact science, I bought my Z 9yrs ago and swapped out the OEM air panel filter for a K&N panel one with no apparent gain or loss in performance, not long after I then done away with the OEM filter box complete and added a K&N cone filter with no apparent loss or gain but this was unshielded and only fed from the very limited air ways around the n/s headlight. Recently I decided to shield the filter from the high temps in and around the engine bay, I did notice a smoother take up of engine revs but nothing really significant but again no loss, I then looked at the airway provided by BMW to the filter and wondered why IMO it wasn't taken from the kidney grill direct to the filter and so decided to steal some air from the kidney grill and try and route it as direct as I could to the filter thus giving the engine more chance of receiving as cool an air charge as possible which I believe I've done, now!!!!! There is no proof that this has any more effect on performance than my own feelings but at least I know that I've given my engine a better chance of receiving the coolest air possible at any given time, this has got to be more beneficial than not bothering and telling others that because it's not a big HP gain it's not worth doing. Do what ever you feel makes sense and you can't go wrong, fit your K&N and only very lightly oil it, the people who have oil on senser probs have IMO over oiled and I believe K&N should pre oil their filters thus alleviating this not so common problem, (very easy on the oil) after all there's plenty of filters out there that are dry and they also work well. If nothing else it'll give you a bit of a under bonnet growl. Look under "Performance" Kitchen waste bin if you haven't already.
Roy.