garuda

http://www.bobistheoilguy.com/airfilter/airtest1.htm


An interesting read. I don't know if it has been posted here before.
Makes you wonder if you should stick with OEM filter or other good quality paper filters. For normal street use, the marginal potential for improved flow with an oiled filter may not be good if you are thingking of keeping the car for a long time. If you are leasing then :whocares:

techguy

I have used K & N for years. I would agree with his logic that a higher flow filter will potentially have lower filtering performance. K & N took out their air filter for the 04 TL after some reports that it did not fit well.

Aegir

There are about a bazillion of these discussions in forums and sites across the net. :search:

Go to the second-gen forum and I'm sure you'll find members who've logged 100K+ on K&N's and are still going. I ran my last Mustang for over 10 years and 100K miles on the same K&N, and it was still running strong when I sold it. They aren't a fly-by-night company. They make a good product that has withstood the test of time.

A K&N may improve mileage and power. That is often debated, but what is certain is that a K&N will pay for itself when compared to the cost of OEM paper filters.

garuda

True that most of K&N owners are very satisfied with their purchases. Some have logged more than 100 000 miles on a set of KN with absolutely no problem. However, the cars being built today have much more closer tolerances than ever. That is why we are using 5W-20 oils instead of the typical 10W-30. I am just wondering if the very small dirt particles that would have been fine in older design engines will somehow affect our very efficient and "tighter" build engines. Will it also affect and degrade the emission control over time?
I guess when K&N releases a proper model for our car, I will have to really think about this issue further.

Road Rage

The 5w20 is not for tolerances, it is for mileage and emissions. See my post on topic. The tolerances in the shop manual between my 2002 TL-S and the 2004 TL are the same. Plus, the BMW M5 has at least as "tight" an engine, and it specs 10w60. So the tolerance theory is one dealers and internet experts state, but it does not hold up to the facts.

However, you are right about dirt being more of an issue. Dirt particles of 8-10 microns do little damage by themselves - it is when two small particles get side by side that they can cause cylinder and ring wear, as they sum up to the largest two adjacent surfaces.

I have actually tested K&N and other filters using Test Dirt (yes, it exists) and looking at the filter media under high power microscopes, and counting the particles. The K&N allows more and larger particles than a paper filter with about 5K on it(paper filters have big holes when new, and do not filter too well until about 5K of driving - that is why people who change them every coupla months are not doing themselves much good). It flows marginally more, but that will only produce more power if the engine air intake is less than the engine can use - it seldoml;y is in Honda cars, and the differences are usually only a handful of HP at higher revs - if you rcae, that can make a diff - if you do not, what is the advantage?

The other thing about a K&N is that after cleaning and re-oiling, the gauze cotton threads do not have as many "tentacles" - they seem to conglomerate after cleaning and re-oiling, which enlarges the gaps. I have seen this in lab scope examinations of several I have obtained, which were serviced using K&N kits and instructions. Most people "in the know" use a K&N until it is severely dimished (at about 50K) and throw it away. I think that is cheap insurance, but it does question the "K&N pays off in the long run" theory in my eyes. I do not care about payback - compared to the price of an engine rebuild in either the S2000 or the TL, it is like an ant in the ocean.

I use a K&N on the S2000 - huh? Am I a hypocrite? No, because I put few miles on the car,. and the oil is changed much more often than the TL (once a year, but that is <3k miles). The S2000 is so finely tuned that to have a perf advantage, I need every last HP (I paid $1500 for a titanium Mugen exhaust system which gives maybe 3-5HP, but it weighs 35 pounds less than stock). Plus, the airbox on the S2000 reduces the large particles of dirt that make it to the filter, as thre air makes a severe turn inthe airbox, and a lot of dirt falls to the bottom. I have to vacuum it out regularly. I also do regular used oil analyses, checking for indicators of excess dirt and wear. So far, the combo looks fine.

If the filter fits bad, as many aftermarket filters do, then you will be dumping huge amounts of silicon in the oil, and wear will unquestionably increase.

And while people have no doubt gone 100K or more with K&N's, the pertiunent scientific question would be how much longer might they have gone wiith better air filtration. The argument would be like saying that a smoker lived to be 65, so smoking must be safe.