Ok, so technically it isn't a "bolt-on", it's a "drop-in"... but I'm wondering if anyone has tried the K&N drop-in filters on their 2012 Si?
http://www.knfilters.com/search/product.aspx?Prod=33-2473
Any difference/improvements when using it (whether it be fuel economy or power related)? I heard that they were supposed to be pretty good compared to OEM but curious to see if anyone has actually bought one.
Sorry about this in advance and I know that I will NOT be popular as many K&N fans are very passionate in their faith in this product - but I have had bad experience with them.
K&Ns, and others like them, flow very well when other normal filters get dirty and clogged - that is because they do not actually do much filtering!
I ran one for just 3 weeks in clean city environments and then went to a track day where my porblems was super high oil temperatures. So the next day I drained the oil and just for interest sake on overheated oil sent an oil sample to a friend who was dating the only oil analyst in town (nothing like having free oil anaylsis service!). She phoned me immediately to tell me that I had an air filter breach and that she had found large amounts of silica sand in my oil and found bits of worn chrome steel etc. etc. I immediately inspected my filter installation and found that the filter lip seals mated the filtter housing well - so where was the dirt getting in? I then inspected the K&N very carefully by holding it up in front of a light and folded out one of the pleets - and could just not believe my eyes - it has absolutley nothing to stop dust. Sure with the pleets all folded in the jig-jag pattern they look good - but have a close look and you will be shocked.
Oh, all my friends give me theories on how poorly I oied the filter - but seriously, a 2 liter engine running at 6000rpm pulls in about 3000 liters of air a minute (cause its a 4 stroke) and so just how many minutes or hours do you think that the oil will stay on the filter's cotton threads.
Don't believe me? O.K. - next time you are about to oil yours - spend 20 seconds holding it up in front of a light and fold out one of the pleets and decide for yourself.
I will never again use them nor any other brand that does not claim any filtration properties. To their credit, K&N make many claims about flow but none on filtration. [Injen now seem to have a filter that they do make filtration claims and I would like to look at one of those.]
I also concur on the dyno results - we once had a customer's car on a dyno and found that was short of a few horsepower right at the top of its rev band. We found a slightly dirty OEM filter so removed it and the power was back to where it should be. The owner had a K&N and requested we try it - obviously there was no improvement (you cannot improve on an open air intake). We then persuaded him to try a brand new OEM paper filtter and guess what ?- it still made the same full power. Problem is that a lot of fiilter and housings are made rather small and do get dirty quickly to the point of starting to block flow. Remember its not likely to affect anything a low revs (unless its absolutely filthy!) - so probaably the best is just to keep replacing filters whenever they look dirty.
O.K. so now to sit back and wait for the incriminations.......just remember I am just telling of my bad experience - its a warning to those that may choose to listen.......and just for the record I do not currently work in the auto supply industry - I am just a driving enthusiast or "petrol head" as the English like to say and yes, I just cannot wait for my newly ordered 2012 Si Sedan to arrive - scheduled to be built next week!