K&N airfilter for the Prius. Good idea?

This topic has been re-invigorated because K&N now has a part that fits the current model Prius w/o modification.

I have used this air filter for a long time in a 2001 Prius. IMHO its sole advantage is not buying a succession of paper filters. There was no power or mpg increase for me.

Two potential 'negatives' are that after re-oiling the filter, oil may drip on (and damage) the mass air flow sensor. Avoid that by draining the AF on paper towels after oiling and before reinstallation.

Second is the possibility of allowing dirt into the engine. Monitor for this with used engine oil analyses. I have not had that problem so far but it is certainly part of K&N's overall reputation.

 

I'd agree that the K&N filter insert gives very minor horsepower and economy improvements on small displacement cars at best. I've used them on my Miata that I raced, and never was able to measure a difference. Of course in racing you will take any improvement you will get so I kept using it.

The studies I have seen also show more dust and particulates getting past a correctly oiled K&N compared to a stock paper filter. Probably not enough to do any damage, but you never know.
In addition there is the possiblity of contaminating the MAF sensor if you overoil the filter.

So, best case you may see a very tiny improvement in MPG or power, and if oiled correctly you shouldn't cause any problems. It's up to you to decide if it's worth it.

 

I have the 'jury-rigged' K&N filter (modified the K&N for the First Gen Prius to fit my Second Gen), and in all honesty can't really feel a difference between the paper and it. I'm with Tochatihu in saying the only benefit is not having the recurring cost of a paper filter. The Prius isn't a fast car, I'm going to be getting a Mitsubishi Evo IX to fulfill my 'power cravings'. It's a wonderful Daily Driver though. Saves tonz on Gas!

 

All of the above are true. I have also had many K&N filters on previous cars (short rams, cold intakes, I-4, V-6, turbocharged). There is very little gain (+1 to +3 hp) in 4 bangers but since the Prius is super stingy with fuel you probably will see 0hp increase.

The only reason why I'm planning on buying the K&N is for cost efficiency. The dealer quoted me about $25 for a paper filter or I can spend $40-50 and have a lifetime filter. The biggest worry is properly oiling it...remember light coats rather than heavy ones. If you do buy it, I personally recommend checking it every 30,000 miles for possible cleaning/re-oiling.

The cleaning kit is about $12-15 on most auto shops and does not come with the filter (unless a store as a promotion).

 

As I've posted many times, not only is the Prius a fuel-efficient 4-cylinder, but it's also a Miller/Atkinson cycle engine, which means that it closes its intake valve late and *never* gets a full charge of air and thus requires even less air than any standard engine.. My calculations say that even at max RPM (which is again, not that high- 5000 RPM), the Prius engine requires less than 250 CFM air flow, which is easy for just about any air induction/filtration system, including the stock Toyota system, to provide. Thus replacing the filter with a higher flow version does not net *ANY* benefits. The only benefit of the K&N in a Prius is the fact that it is washable and reusable, but as mentioned, watch out that you don't over oil it- too much oil will kill your air flow sensor, and it will cost you a couple of hundred for a replacement- one air flow sensor replacement will eat up all the lifetime savings of a washable filter, so be careful!

The only reason I have one is that I noticed water tracks in the air box after driving in wet weather and from experience using vacuum cleaners with washable filters that are not quite dry, I know that wet fiber media filters show dramatically increased flow resistance (not from dirt, but because the fibers swell when wet, and also because of water films across the small openings, both of which combine to severely restrict airflow)... Thus I drive with a K&N during wet weather as the oiled media can handle the water better (oil repels the water so it doesn't soak or clog the media), and the air particulate count is much lower during wet weather so I don't worry as much about dirt getting through, and then in the spring and summer, when it dries up and there's much more dust on the roads, I'll swap in a genuine Toyota filter..

 

<div class='quotetop'>QUOTE(silentak1 @ Nov 13 2006, 02:27 AM) [snapback]348083[/snapback]</div>

I'm having a problem seeing the economy of this. How often do you have to clean/oil the K&N, in other words, how often do you spend the $12-15 for the cleaning kit? That's about the price of a good non-dealer paper filter for this car.

 

<div class='quotetop'>QUOTE(Beryl Octet @ Nov 13 2006, 12:15 PM) [snapback]348243[/snapback]</div>

Another source of cheap stock Toyota filters is ebay. I got one engine air filter for $13.50 shipped. Two cabin air filters for $19 shipped.

 

<div class='quotetop'>QUOTE(Beryl Octet @ Nov 13 2006, 11:15 AM) [snapback]348243[/snapback]</div>

Let's assume...

OEM paper filter: $25 every 30,000 miles

K&N filter + kit: $55-60 and the kit should render 4-5 cleanings (120,000-150,000 miles)

The equivalent of the OEM filter for 120,000 miles would be about $100 more or less.

Now if improperly re-oiled the filter can cause damage to the Mass Air Flow sensor (MAF) which will cost over $250. That's not exactly economical so spray light!

 

<div class='quotetop'>QUOTE(Beryl Octet @ Nov 13 2006, 12:15 PM) [snapback]348243[/snapback]</div>

Agreed. It sounds like a pain to me, for little or no performance gain...and then there's the issue of mucking up the airflow sensor...

And that doesn't include what my time is worth, cleaning and re-oiling an air filter.
I'd probably do it wrong, anyway!
[smile]

 

<div class='quotetop'>QUOTE(Pinto Girl @ Nov 14 2006, 04:31 PM) [snapback]349087[/snapback]</div>

I'm not arguing about performance. I openly state that this filter will do NADA in terms of hp.

Cleaning and re-oiling only takes 30-60 minutes every 30,000 miles or so. And most of that type you are just waiting for the filter to dry. Actual physical work (removing the filter, cleaning, spraying oil) is more or less 10 minutes.

What I am saying is that this is a cost-efficiency alternative to the OEM filter as long as one properly maintains it and lightly re-oils .

But you are right. The safest and easiest replacement will be OEM.

 

i puts the K AND N on my prius and it did wonders. Iwill gladyl buy a 2nd one for her. B)

 

I think I'm just trying to idiot proof my life...afraid that I'll put on too much oil and make a big mess where there was none before!

 

Re-oiling is not a problem as long as you let the filter dry. I had the same issue with my wife's G35. I let the filter dry overnight and there was no problem.

I received my new KN filter yesterday. Installation will be this weekend with mileage updates to come later.

 

<div class='quotetop'>QUOTE(frogcatcher @ Nov 15 2006, 02:38 PM) [snapback]349662[/snapback]</div>

And what wonders did it do?

(I'm just waiting-and baiting--for someone to say it increased gas mileage)

GeronimoPFudgemuffin