daveparkinson
Member
fitted a k&n induction fillter made a difference more miles per litre and what a great sound easy to fittook 45minutes 
air filter
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daveparkinson
Member
go on to k&n web site its all on there price what kit to fit your z4 you will love it
Liverpool
Are we talking about a panel filter to replace the original (proven to offer no power/fuel economy or sound difference), or a 57i 'hot' air intake system (proven to reduce power, lean out the engine and make a little more noise).
BTW, the 57i kit is only available for the 2.2 - the only items listed for the other models are panel filters (see above) and oil filters (why when a genuine BMW one is cheap & guaranteed?).
BTW, the 57i kit is only available for the 2.2 - the only items listed for the other models are panel filters (see above) and oil filters (why when a genuine BMW one is cheap & guaranteed?).
daveparkinson
Member
k&n induction kits are for 2.2 2.5z4s cost around £87 easy to fit your self
They all clog up, and some of the 'airflow' benefits of the aftermarket types are simply due to having less area in the folds than a standard one, which means you let in more dirt.chris said:mmm-five said:
Bit negative
Panel filter will keep power up though, as paper ones do clog up very easily. And unless you change them every six months, aftermarket panel filters are better imo
I do change mine every 6 months, or whenever I do an oil change (which is about every 6,000 miles in the \\\M), as I think the 15,000 mile intervals are just too long.
A
Anonymous
Guest
chris said:Bit negative
Panel filter will keep power up though, as paper ones do clog up very easily. And unless you change them every six months, aftermarket panel filters are better imo
But that's a good thing isn't it? The stock filter is doing it's job of cleaning the air! This helps to protect the engine. More pollutants going in the engine causes more damage. I'm sure BMW have spent a little bit more money on R&D than K&N to stop warranty claims on engine damage from sucking in crap!
I personally would have the protection of stock filter rather than the potential of 2 or 3 insignificant BHP's!
Unless your car is heavily modified such as a big after market turbo and fuelling to compensate - your stock'ish car doesn't need to suck in more air. Each to their own though - you might prefer the noise change for example with a K&N filter.
Shipkiller
Veteran
Read this:
http://68.230.199.103:8080/AirFilters.html
http://68.230.199.103:8080/AirFilters.html
Interesting read, and about the same as everyone knows really. Most aftermarket filters let in more dirt, but still is this harmful to the engine? At what size particles are they talking about? Plus these were all new filters, and the main reason for changing from a std paper element, is that after as little as 6 months or less get clogged up, and some produce a 1/4 of the airflow as they did when they were new! This is why aftermarket filters are better.
Personally i would not use K+N as i dont think they are brilliant, and prefer pipercross (foam filter) or HKS or Blitz, but Blitz filters do let in more particles of dirt than others (in the tests ive seen).
RR results were done of about ten different makes, and different ages which not many do! And unless you change the paper element every 6 months then you are alluding yourself.
Each to their own, as its your car. But ive always used HKS tripple layer filters with no problems and a good power gain and less restriction through the revs, but a suitable airbox has to be used, so when waiting in traffic you do not get heatsoak, or less than you would get without one.
Personally i would not use K+N as i dont think they are brilliant, and prefer pipercross (foam filter) or HKS or Blitz, but Blitz filters do let in more particles of dirt than others (in the tests ive seen).
RR results were done of about ten different makes, and different ages which not many do! And unless you change the paper element every 6 months then you are alluding yourself.
Each to their own, as its your car. But ive always used HKS tripple layer filters with no problems and a good power gain and less restriction through the revs, but a suitable airbox has to be used, so when waiting in traffic you do not get heatsoak, or less than you would get without one.
I run K&N on my Jeeps for a very specific reason that if they get soaked in competitive off road conditions they can still function (which they do even with snorkels and pre filters). In dusty conditions I can clean and re oil mid event if required.
I also have one on the Zed that I was given FOC and keep meaning to replace it with OEM. It has NO effect on performance, NO increase in induction noise and simply allows, as noted by those above, more particles into the engine. IMHO something to leave alone and stick with the quality of a BMW filter and have an engivne that will last a lifetime.
As an aside in a non scientific way my observation is that the K&N has far fewer folds than a paper filter. It's therefore likley that the paper allows much greater effective surface area and thus smaller filter mesh than a K&N for the same air volume.
I also have one on the Zed that I was given FOC and keep meaning to replace it with OEM. It has NO effect on performance, NO increase in induction noise and simply allows, as noted by those above, more particles into the engine. IMHO something to leave alone and stick with the quality of a BMW filter and have an engivne that will last a lifetime.
As an aside in a non scientific way my observation is that the K&N has far fewer folds than a paper filter. It's therefore likley that the paper allows much greater effective surface area and thus smaller filter mesh than a K&N for the same air volume.