Here is my take on K&N Filters and why i will never use them again.

I have used them in 4 of my past 5 cars so i am very familiar with how to clean them and hwo they perform.

When i had my 01.5' Turbo Diesel i was meticulous with all the service and upgrades. I had the larger turbo, larger exhaust manifold, bigger injectors, two fuel pumps, all Mag Hytec pans, etc, etc. I run nothing but Amsoil and had the dual bypass filter kit as well. I was doing lube oil samples every 10k and oil changes every 12k.

I installed the K&N filter (brand new, pre oiled) when i hit 30,000 miles and added the larger turbo. 10K miles later, my silicon level in the oil sample went from 6PPM to 18PPM. At the next sampling 10k later, the level was 27PPM. So i went back to the paper stock filter and low and behold at the next sampling, the Silicon level dropped back to 8PPM.

So that (and other peoples results seeing the same thing) has made me steer clear of K&N filters.

1. They are not as effective as paper filters for stopping dirt.

2. As others have pointed out, offer such a minor increase in power and MPG that it's almost not even noticeable.

3. Price wise? I can get a Wix paper filter for $13.95. A K&N for $47.99. Changing out my paper filter every 30K to date has only cost me less then the price of a K&N. So the argument that you save money with them is actually not really true. Especially considering that a re-charge kit cost about $10.00 and will typically do two full cleanings and re-oilings. So the filter and the recharger kit will run you about $60.00.

Do the math..

K&N Filter on a truck you buy new and keep till it hits 120K miles.
$48.00 for the filter. If you clean it every 30k miles, that would need two Recharger kits at $10.00 each. Total investment: $68.00

Effort to do the filter cleaning: (Following instructions) Remove filter, Clean heavy dirt with a brush. Spray with cleaner and let it soak for 10 minutes. Then rinse with water (Which leaves nasty residue wherever the water goes) and shake out excess and let the filter dry naturally (Which could easily be upwards of an hour, but lets say an hour for arguments sake). The spray with the filter oil (takes about 3 minutes) and let it soak 20 minutes. Then check for any missed spots and spray again. Then finally re-install the filter. Total time: About 1 hour and 45 minutes and with considerable mess between the cleaner and the new oil.

So grand total for eveything: $68.00 plus 5 hours and 15 minutes time spent on cleanings over the course of you owning the truck.

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Paper filter on a truck you buy new and keep till it hits 120k miles.
$13.95 for the filter. Since the truck comes with one right from the factory, you don't even need to touch it for 30k miles. So you would need to purchase only 3 more filters for the life of the truck. Total investment: $41.85

Effort to do the filter cleaning: None. Remove old filter and throw in the trash. Drop new filter in. Done. Absolutley no added work.

So grand total for eveything: $41.85 and no cleaning labor or time whatsoever.

Someone tell me now how K&N filters are a better bargain and will save you money???

 

The biggest single difference is the mass of the filter. A cone filter can flow up to 150% more air than a flat filter, reason: More surface area to let in air.

I have a K&N drop-in in my Jeep, have sent my oil out for testing and contaminant level was slightly higher than with a Mopar paper filter. Not enough to make a difference, IMO.

I have a K&N cone filter in my CAI in the truck and have sent that oil out for testing and yes, it did come back higher than the stock setup, BUT it's letting in WAY MORE air. Would it be significantly higher than a cone paper filter, I don't think so. Put a pre-filter on the cone filter, it only reduces flow by 2%, did this because the truck is mostly used where over 50% of the roads are dirt roads and off-road in the dusty, red clay dirt of south Georgia.
Results of oil testing with the pre-filter were just slightly higher than the stock, paper, flat filter setup which didn't flow near as well.

Not saying to get one or not get one, just posting up what my personal experience and the data I was supplied by Blackstone Labs dictated...

 

Yes you are right about i'm taking in warm air that was my intention but I got the best of both worlds, I get better gas mpg when I'm light footed hwy or street, But when I floor it the power is there for me, at speed no hot air is an issue!!!!! Think about it!!!!
I'm not exactly sure when they say city mpg because I'm in the BURBS of a million people
and I get 15 MPG but if I go 20 min. east to TORONTO say YOUNG ST. I get not better than 10 MPG because of waiting for lights.
Anyone knowing what and how city MPG is measured get back to me, and is the overhead mpg monitor accurate on my 2007 1500 trx4
THANKS
MIKE
BRAMPTON ONT. CANADA

 

I will be installing 2 thermocouple temp senders to 2 gauge's in my truck to verify the low speed and high speed temp of underhood air temp and rad fins to backup my claims if I am wrong I will gladly share it with all of you, but I am firmly making a stand that when you are at 60 mph the air temp under the hood is only moderatly higher than outside temp because your rad fin temp that surround your cores can only dissapate a certain amount of energy then they stabilize to their capacity and with a high volume and pressure of air flow they accually start to chill to the core insted of radiating. Thats why electric rad fans shut off when at high speed and it is the fundamentals of air conditioning the faster moving the gas or air the cooler THINK ABOUT IT!
P.S. this is only theory at this time as I have not done any trials.
THANKS
MIKE

 

Yes and no. I have never put the stock Ram induction tube that goes from the stock airbox to the throttle body on a Flowbench. Nor have i ever put the throttle body itself on one. But this was one of the issues i remember when i used to be heavily into drag racing and had built two race cars and dealt with induction systems. I had a TPI (GM Tuned Port Injection) set up and was trying to weigh my options on getting as much clean air as possible into the engine but i wanted to draw it from outside the engine compartment. I brought my Throttle body, two different air filters and two different induction tube systems to a shop with a Flowbench and was able to test the set ups i had. That is where i leanred very quickly about how the point in the system with the lowest CFM will dictate how large an air filter you need.

If you (this is a hypothetical example) had an air filter that flows 150 CFM and one that flows 300 CFM and installed them on to a throttle body that flowed 100 CFM wide open, is their any advantage to the larger air filter? And the answer is no. A larger filter has more surface area to flow more air but it's not going to offer any improvement over a stock air filter is that stock filter flows more CFM then the engine can even use. The ONLY advantage to a huge air filter is the fact that the larger surface area will allow the filter to flow a higher CFM when dirty then a smaller filter. And it's not just the throttle body either. Even the tubing that goes from the air filter box to the throttle body can be a CFM limiter. If your thottle body flows 1,000 CFM and your air filter flows 1,500 CFM that is a nice pairing. But if the tube between the two only flows 700 CFM? Your losing out.

I also learned very quickly through a wheel dyno that cold air will give you more Horsepower then more CFM alone. Which is why a cold air induction system which might limit CFM a bit is a much better choice then filters that mount right on top of the engine. Sure a filter mounted right to the throttle body will flow plenty of air. But it's flowing HOT air which is not something you want. A properly sized Cold air induction system is a MUCH better idea.

I saw an increase of 8 HP when i switched from a throttle body/MAS mounted air filter to a cold air kit that was drawing air in from the fenderwell of my 06' Impala SS.

My above comparison of the economics of K&N filters was comparing Stock filters and the stock filter size K&N. I know the larger filters will give you much more flow. But has anybody ever done any flow testing of the stock system Vs the K&N setup?

 

First and foremost, realize that your underhood temperature is not only caused by the radiator. You also have two MASSIVE cast iron exhaust manifolds, plus your cylinder heads kicking off heat. The higher the RPM's, the hotter those manifolds get and they are not in the direct airflow of the radiator. They are a huge factor in underhood temperatures.

You are right that at high speed the air flow through the radiator will cool your engine water temp down without needing the fans. But the exhaust manifolds are still pumping out heat. The split air filter housing you have is putting each air filter right above each manifold. If their was any real advantage to having warm air for induction to give better MPG, then why does *******ly no car company mount at air filter in a location where it draws in hot engine compartment air any more? Car companies nowadays are doing ANYTHING they can to increase MPG by even half a gallon. GM recently announced that a Spare Tire would be an OPTION on some cars to shave off weight. That should give you an idea of how crazy these companies are with increasing MPG. With that being said, the fact none of these companies have stopped installing air intakes that draw cold air that is away from the engine and the airflow from the radiator is all the proof you should need that warm air does not increase MPG in any way.

Not saying you, but i am amazed at how many people seem to doubt car manufacturers engineers when it comes to designing engines. All these major car companies invest millions of dollars to squeeze out as much horsepower as possible using as little fuel as possible. The two biggest numbers car companies love to flaunt are MPG and HP. They know far more about engines then almost any of these aftermarket companies and know what works and what does not. That is why i laugh at things like a throttle body spacer claiming it will add 10 HP. Right, like Chrysler Engineers were too stupid to think of that. It's all BS. And if they could squeeze 10 more HP out of an engine by simply using a different style of air filter, you honestly think they would not do it?

The only exception i have ever seen with car maufacturers not using a proven idea to get more Horsepower is if it does any of the following four things:

1. Makes the vehicle too loud. (Free flow exhuasts as an example)
2. Hurts reliability/Increases maintenance.
3. Lessens MPG.
4. Hurts emmissions.

Taking those four things into account, if it does not do any of those things and the car company did not install it, it likley is not worth installing on your own.

 

I bought one of the K&N drop in filters for the standard box about two years ago. I didnt notice any difference i just wanted an air filter i didn't have to replace every six months. I live on blacktop but i do a lot of gravel and dirt roads and its cheaper in the long run to get the reusable filter at least it was for me. I agree i also got three cleanings out of a drop in K&N filter recharge kit.

 

You guys either bought a smaller recharge kit than i have or you are using way too much oil in them. I bought my kit from a bike shop to service the filter on my harley. I have cleaned and oiled it 3 times, my truck twice, and my buddy's bike once, and stil have some left.

 

NV290 you sound like a very knowlagable person, I'm not going to wrestle with you on your reply to my comment because you make allot of sence but in the same breath everything you said about the energy radiating off the block and exhaust mannifolds is an obvious fact if the engine was sitting in a dyno room where air is for the most part static, in a vehical travalling at 60 mph the math changes, I respect what you said and drawing from that I have a question for you after my thermocouple test I plan to install a foced air hood scoop and fab a plexiglass housing arround my filter setup totally sealed to the hood when closed, now back to the question will this decrease my mpg do to the fact that air temp sensor and mass airflow sensor will be noticing a change and be dumping more fuel into the engine and can my program in my processor keep up with the change? or because of the obvious increase in HP that I will aquire mean that I dont need to open the throttle as much to maintain the same speed in return have better mpg? what is the math on this?
Hope to hear from you
MIKE
BRAMPTON ONT. CANADA
it's cold up here eh!

 

I like the fact that I never have to buy another filter. Normally just clean it when I am messing around in the garage some weekend.