I think others must have mentioned K&N filter before, but I am too lazy to search so pardon me if this is a repeated topic. At least I try to provide more details, so here we go:

The throttle response of my car had become a little sluggish and did not match well with the 1-4 gear changes, so I did a throttle reset which helped removed some delays and made the gear changes more in phase. The throttle still felt somewhat muted afterwards, so I figured it could be the air filter since I did not know when the last time I had it replaced (if ever!).

I decided to go with K&N. I had used it before on K24, and also foam-type filter as well, so I know the key benefit of these aftermarket filters is the better throttle response, not more power.

I am glad to say that the filter works quite well on RDX. The throttle feels quite a bit lighter than stock filter, and the engine responses quicker to throttle pedal input. Best of all, I feel it is easier to catch the point during <10mph re-acceleration where just enough throttle input brings the engine comes back to life. Before, with stock filter I occasionally overfeed the throttle due to the lag in response, and that would cause a jot similar to a clutch dump. K&N also reduces engine drag during coasting, similar to what I experienced on K24.

I cannot say if there is any power increase since I don't believe air filter itself change power much, but at least I do feel no drop in low rpm when the turbo is offline.

 

I think the only concern with performance filters is, since they allow more air in, this will also allow more particles in(especially in dusty areas), which could potentially damage the engine. This is what stopped me from upgrading to one. Any long term users that can chime in?

 

I’ll chime in on this. I’ve used K&N drop-in filters in almost all my past cars. 250,000+ miles total. Never had one problem. High flow air filters come as standard equipment today on many performance engines. To me, the benefit of a high-flow air filter is to decrease air-intake resistance when the car is fully floored. It reduces pumping losses on the intake side, which slightly increases engine efficiency when floored. It helps the engine rev a little faster (improved efficiency = more torque = better acceleration) and add perhaps 5-7 hp at redline on 271 HP engine. But it will not improve fuel economy.

In exchange for less air resistance, the K&N will not filter air as well. If I lived on dirt road, I would never own one. But the only time I see “dusty air” in suburban New Jersey is after snow storms. The road-salt applied to melt snow often forms white clouds of salt in the air. In winter, I remove my K&N filter and put back the OEM paper filter. Come Spring, the K&N goes back in. Also, I rarely oiled my K&N filters. I just hosed them with water to keep them clean, usually with each oil change. Some people saturate the filters with oil, which can “smudge” MAF sensors. That’s not good.

I will add one more thing, when I installed the K&N panel filter in my RDX, the process was not as easy as in my other cars. One of the RDX’s airbox screws is covered by the cold air intake plumbing. There is an extra step required to access the air filter. I usually clean my filter a few times a year, so the RDX makes that less convenient. In the end, the K&N filter might shave a 1/10th - 1/5th of a second off the 0-60 time. Nothing major, but why leave that on the table?

 

I personally think the majority of RDX owners don't care about leaving 1/10-1/5 of a second off the 0-60 time on the table.

 

You're probably right. The RDX's demographic is not quite like that of a 510 HP BMW X3 M, a 469 HP Mercedes-AMG GLE, or even a 354 HP Audi SQ5. But then again, unlike a Lexus or a Lincoln, the RDX has a fun factor and attracts a more enthusiast crowd. The RDX also has owners who have upgraded the turbocharger, downpipe, injectors, intercooler, full tune, run E85, etc. To each his own I suppose. On a $40,000, semi-sporty, luxury SUV, spending $50 to create a little more pull when entering the highway is worth it to me. It gives me the most from my premium fuel .

 

A tenth or two is one to two lengths in the quarter mile respectively. I care about that.

It is true they don't filter as well as paper. Motocross guys use them in heavy dust, but always with prefiltering screens known as "outerwear". That speaks volumes about the compromised filtering. That said, I agree there is no problem using them if it is known the vehicle will not venture beyond relatively dust free areas, clean city streets etc. Over the years I have grown lazy regarding the cleaning. It just takes too long getting all the oil out, and especially picking all the bugs out of the pleats. Much easier to just toss in a clean stock paper filter and be done. Maybe i'll revisit the K&N just to see what it does.

BTW did I read that right....you don't oil them? Run them dry?

 

Pretty much never oiled it. I was always concerned about over oiling it. Even after a dozen water rinses (60,000 miles or so), the filter still had an oil film on it. In the past with older filters, I’ve given it quick light spray with WD-40. That does not leave a heavy film.

AEM and Airaid are K&N competitors. Both of those are essentially “dry” K&N air filters. Both are cotton mesh, as are almost all of the cone filters used on SRIs and CAIs. With each oil change, I knocked out the leaf fragments, bugs, etc. from my K&N air filters and gave it a quick water rinse. Never had any problems.

 

oh, a mistake. Clean and oil like you are supposed to. I have used them since the early 90’s. Just follow the manufacturer directions, they are made like that for a reason. But, alas, engines are the last thing to wear out on a car as we all know… for the most part. I ran kn’s on a vette for 20 years, and a Toyota 4Runner for the same. All lasted over 300,000 miles. Using stock for my RDX. I think too sensitive to dirt these days, with a ktune, and a pumped turbo, that just means more air…more dirt… ore wear

 

This is a subject that never dies. If you feel it will save you money in the long term and that it will improve throttle response, by all means go ahead and buy into the hype of K&N.
What ever you decide to do, make sure that it is properly maintained and oiled. Running one dry is comparable to using window screen as an air filter.
A scientific test of standard, Unifilter and K&N air filters

 

Did anyone else notice with the K&N Drop in filter the sealing gasket does not seat into the top bevel of the Airbox?

Both the OE and K&N will both have slight side to side play when placed in to the Airbox housing, however, the K&N fails to fill the area outlining the Airbox cover.

Since the Airbox cover uses this as a partial seal I'd say this will most certainly take in un-welcome particles that would be exposed on the top side of the filter.

Just wondering if anyone else had this same problem with the drop inn.