Has anyone tried K&N Engine Air Filters?

Yea, have used them on motorcyles for years none better. Don't know if we would see much gain in horsepower in our anemic prius's though i think they are only a couple of more bucks than a stock one anyways. they are cleanable and re oilable. looks almost like red transmission fluid on them when they are new or re cleaned and oiled.

I will put one in soon. order on line or go online get the # and order through Advance auto parts and let them pay the shipping.

peace

 

For Classic owners, note that since the filter sits above the mass air flow sensor, there is some possibility that excess oil from the K&N filter may clog the MAF.

 

Don't expect an mpg increase. The only way I see that one should be expected is in high throttle opening operation. Why? Because the throttle valve itself is controlling the air flow. If you have a low restriction air intake but are running low throttle settings (normal driving) the pressure drop is being taken across the throttle valve--so there is no net difference. The engine will produce the same power with the same quantity of air and fuel, but the throttle opening will be slightly different. Perhaps there are some vehicles that respond differently because of some aspect in their control scheme, but I'm not sure how unless they are running leaner as a result (and that seems unlikely with modern O2 sensor ratio management.)

What the K&N does do well in some vehicles (like my former 240 and Accord) is to provide more power at high throttle openings. I used air horn set ups that were even less restrictive but the benefit to acceleration was easily felt and measured. For this reason a K&N would make sense if one found that they didn't have enough power for passing or hill climbs. I could see this being an issue on mountain passes for example where the higher elevation reduces effective horsepower, and the traction battery will be tapped out sooner on long hill climbs.

 

I had one of their intake systems in my Tundra 4.7. I didnt see any mileage change. Only thing to watch out for is over-oiling. I put the intake in at 16,000 miles and at 32,000 I took it out to oil it after going offroading for 2 months straight and when i did this i chose to check the MAF Sensor and the Throttle Body.

The throttle body adn MAF were both black, picked up 2 bottles of cleaners, 1 MAF and 1 TB and it ran as good as new.

 

Used (still in use) in 2001 Prius. No detectable change in engine performance or efficiency. The oil drip onto MAF is a potential issue that can be managed by proper draining after filter re-oiling. Less of a concern 2004 forwards because of different airbox design.

Throwing away less paper air filters is the only real advantage.

K&N has a poor reputation (possibly deserved) because it may be less effective than paper in removing smaller particles. As such, I think it should only be used by Prius-people who are willing to monitor used engine oil chemistry and keep track of Si/Al ratios.

May want to tap the bugs off frequently (as with any air filter) and clean/re-oil on 30 K not 50 K intervals.

 

I cleaned my K&N's about every 15 to 20K miles. They usually had a fair bit of gunk on them by then (and leaves and bugs and sand). That illustrates that the filters were working as intended. I ran about 7k miles between oil changes with Mobil1. The 240 saw redline full throttle acceleration daily and didn't suffer any problems that I could detect over 100,000 miles (and 50K before that with stock filters.) I fully expected to tear up the crank due to the nature of the unbalanced four banger running at 7000 rpm with an extra 15% in horsepower due to mods, but it never gave any trouble even though it was a known weakspot for racers of that engine.

I didn't do any special monitoring of the oil.

I let the filters sit and self-drain for several hours after reoiling, wiping any wet surface rubber. (240 had an MAF, Accord was MAP control.) The way these were installed with airhorns and no box, any drips from sitting on the car would have been into the engine bay rather than into the intake line/MAF/throttlebody. This differs from the Prius set up.

 

Doesn't this imply that dirt was passing through the K&N filter?

 

I used one on my '98 Z-28. The oil analysis showed it filtered as effectively as any paper air filter.

Still, the purchase price is steep, and it required a thin piece of stick-on gasket to make it fit my application precisely.

Cleaning them is easy to do. I placed mine on a towel to wick out the water so that it would dry faster. It's still an over-night dry time.

You should not over-oil the filter, though it can be easy to do the first time or two you do it. Too much is not better in the case of spraying on the filter oil. Some vehicles are more sensitive to over-oiling than others, so YMMV.

My personal opinion? I use paper in all my vehicles now. Too much money for multiple vehicles, and it's hard to beat a remove-and- replace filter changes.

 

Seeing that this fellow didn't check for two months of off roading I would expect some mess in the intake manifold, but black? I wouldn't be too sure about black. Grey in the city and tan in the boonies, but black sounds extreme. Might we take this story with about an ounce of salt?

My experience with K&N filters has always been positive, but then I always kept up on my filter maintenance. In fact, clean and re-oil after every race was the rule. Anything else is simply unacceptable.

Two months off road, indeed. Was that in your Prius? Oh no, it was a Tundra.

The benefit of K&N filters for Prius owners is less expense for filters; even re-oiling is cheap. K&N sells that nice, red oil, but Marvel Mystery Oil works equally as well and is really cheap to buy at the local Walmart. You figure out your own dropper bottle.

Oops, gave it away.

Basic oiled filter technology has been constant since filters were first devised. Starting in the early twentieth century, shredded copper or bronze was made into a blanket placed between two concentric metal screen cylinders. The resulting filter element was soaked in engine oil. After a drain period the filter element was placed into the resonator/air cleaner and reattached to the carburetor. K&N uses something other than shredded bronze or copper for the oil carrier. The passages are finer and the area larger, ergo better filtering than those antiques from the twentieth century.

 

The gunked up filter oil is dark gray/black in the areas I've been. Since he mentioned over-oiling, anything that passed through is going to collect on any oil film in the intake/throttle body. I would expect it to be slightly black and to wipe away easily. (Could be from other causes like EGR soot but I doubt it.)

 

I used K&N filters in my Saturn Vue and Ion for about a year. According to K&N's literature they work better after some dirt build-up. The carrier oil was never an issue according to the oil analysis. If you change your oil at 3K the dirt is not a big issue, but with a synthetic and multiple oil analysis, I found my oil was polluted very quickly with contaminants passing through the filter. The lab suggested swiching back to a good quality paper unit. Saturns burn very clean so they have a very small filter and it loaded up very fast.

For racing where oil is changed frequently, they allow more air in and seem to boost performance and dirt is not a big issue.

When buying paper filters, check the charts for a Tier-1 filter. They cost a bit more but filter better and longer. You may be surprised at the rating your filter has. I keep an extra just for camping/driving in dusty conditions.

 

The closest thing to "According to K&N's literature they work better after some dirt build-up" is the starred sentence in the following K&N brochure quote;
"[FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][FONT=Arial][SIZE=2][COLOR=#000000] All K&N Air Filters are washable and reusable. Your normal driving environment will determine when you should clean your air filter. If you drive in a non-dusty wet environment with lots of trees and vegetation, we recommend you inspect your filter every 50,000 miles. If you live in dry or desert conditions, we recommend you inspect your filter every 30,000 miles. Extremely dusty conditions such as driving regularly on dirt roads would require even more frequent inspection. A filter inspection does not necessarily mean it needs to be cleaned. An inspection should be visual to identify the amount of dirt build up on the filter.***** There will always be dirt and this can even help filtration.***** Only when the dirt build up becomes excessive should you make the decision to clean the filter. A K&N filter can accumulate dust up to 1/8th of an inch before cleaning is required. The easy way to make this determination is to see if you can visually identify all of the visible aluminum wire mesh on the top of the pleats. If it is still visible, the filter does not yet require cleaning and can be replaced in the vehicle. The next subsequent inspection should occur in 5,000 to 10,000 miles, once again, depending on driving conditions. Once the aluminum wire is covered with dirt and no longer visible in some places on the exterior of the filter, it’s time for cleaning."

One might be able to interpret the starred part to mean a K&N filter works better when dirty but they clearly say to clean their filter after sufficient dirt build-up, indicating it works better when clean. A possibility does not mean always.

[url]http://www.knfilters.com/audio/audio_book_mp3.htm[/url]

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I have had my K&N filter installed for 15,000 miles and I just removed it to clean it. I noticed a significant decrease in engine noise with a temporary Fram paper filter.
I live in the desert and drive to the polluted city so the paper air filters get filthy and have to be replaced every 15,000 miles. The K&N doesn't seem to make a noticeable improvement in mpg or horsepower.
When I installed the K&N I also changed from Goodyear Viva2 to Michelin X-Radial DT tires. I suspect the tires are the cause of the drop from 49 to 44 mpg.

 

If what you say is true, you have some significant problems that have nothing to do with K&N filters.

Exactly what engine noise was significantly decreased?

I can barely hear when the internal combustion engine is running, let alone hear any intake noises. The only time I definitely hear the ICE running is when the battery is low.

How could you know if there was an improvement in horsepower?

Usually the acceleration horsepower comes from the electric motors and the battery. The ICE runs flat out only when extreme demands are put on the system. Telling which motors are supplying the power normally is extremely difficult to determine.
The system is designed to use the ICE as infrequently as possible. It runs electric as much as possible and is programmed to reduce the power demands on the ICE. It uses as little gasoline as possible and regeneration is a primary source for "new" energy.

 

I should have mentioned that the engine noise is only louder when accelerating from 20 to 70 mph to get going on the freeway. The K&N filter doesn't make any difference otherwise.

I have replaced the spark plugs with NGK Laser Iridium's and also put in a new PCV. The store was out of stock on the K&N cleaning kits so I'm still using the temporary Fram filter.

Every 2 weeks I put the tires back up to 39/37 psi but the mileage seems to have dropped a couple more mpg. It is cooling down from 70 to 50 in the morning which could be the reason otherwise something needs attention. My wife is now complaining about the exhaust smelling worse than before the spark plug replacement but I haven't found any leaks.

 

See these links:

Prius heat-efficiency mods
John's Stuff - Toyota Prius and more

There are other links for techniques using 1/2" water pipe insulation to fill the grill and block off cold air, thereby increasing efficient running of the ICE. I just can't find them at this time. Anyone else?

Your wife's nagging is your problem.

A smell is usual with inefficient, single catalytic chamber exhaust systems. The dual chambers on a Prius are highly efficient. There should be NO smell. Take it, and your wife's nose, to the dealer. It's part of the long term warranted emissions system.

I'd be curious to know when and how your wife can smell exhaust emissions from your Prius.

 

Do not use the K&N filters. There is a problem that their filters do not filter out the small particles very well. I had tried two filters on my wife's car and my own vehicle. After 25k miles, my own car was hard to start. When I had the car in for service, the mechanics told me that there is lot of dirt or particles were stuck on the duct hose, air intake and the engine intake magnifolt. He also added that the K&N air filter is the problem. When I heart that, I was so shocked. Matter of fact, I had cleaned the filters every few months. Then the mechanic fixed it after he removed the parts and cleaned them out.
When I got the car home, I also checked the other car. Not surprisingly, the other car has the same problem. Then I checked the filters very carefully, I found out that the K&N filters don't actually filter out the particles very well. Moreover, the screen actually has larger holes on the screen than the standard paper filters. No wonder the engine has a little more hose power because the K&N does not block out air as a paper filter. The K&N air filters let dirt flows through them as well as air.
Now, it's up to all of you to choose an air filter. But my recommendation, do not use the K&N filters, or your engine will be very dirty.

 

Hmmm, after 105k miles on my 2003 Prius with a K&N air filter since replacing the original paper filter at 15k miles, I have never had a problem. I also don't think that there has been a mpg gain but the K&N has already used 7 fewer paper filters which I expect will be many more by the end of this vehicle's life.

Previously I had used a K&N air filter in my 1992 Ford conversion van for over 270k miles (and 15 years) with no ill effects.

I find that even this small bit of consumption reduction is worthwhile.