K&N Filters......just the facts, please

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#1
So here's what I wanna know.......if I go down to NAPA tomorrow and slap down $44 on a K&N filter for my truck ('88 F250 w/ 4.9L I-6), will it be worth it? Would I notice a difference, or would it just be another cool part to brag about ("Hey I gotta K&N filter on my truck blah blah blah)?

Give it to me straight, no BS. :)
 

Highbeam

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#2
Assuming the rest of your truck is stock ... Unless your current filter is packed with dirt or is very small and poorly designed, you most likely won't notice a difference. The benefit is that you will never need to buy another filter again.

Look at the cost of a traditional filter and how many times you think you'll need to replace it during your time with the vehicle. You may as well also knock a few bucks off of the 44$ for the gamble that you may see some improvement in mpg.

Plus, you get a cool sticker worth at least 15 horsepower. I have a stock K&N replacement on a vortec 350 in my 98 chev, no real difference.
 
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dirt bike dave

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#3
I noticed no improvement in power or mileage with a drop-in replacement filter on my '99 F150. As was mentioned by Highbeam, if you are going to keep the truck a long time it might save you a few pennies.
 

gasgasman

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#4
All they do is make a lot of noise..people equate noise with power.

You have to look further into an engine to realize they don't increase power.
For example, the intake valves are still the same size-they will only flow so much. The throttle body is also only going to flow a certain amount of air.

On vehicles with mass air flow sensors, the K+N oil will actually contaminate it.

Just my $0.02
 

Highbeam

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#5
careful now...

While the valves and throttle body will only flow so much ... that so much is way more than your stock engine normally needs. You have to look for the weakest link to get more air to the engine in the search for power. IF that link happens to be a restricive by design stock air filter then the K&N will improve that peak power. A completely different angle is efficiency, if you're sucking molasses through a little straw or a big straw. It sure sucks to have a little straw and that excessive suckage is extra work. Extra work requires more fuel. The reason the K&N doesn't give the gains it claims is that the stock air filter is usually sufficient on a stock engine. If you go and improve the exhaust (the muffler is a restriction by the same principle) then you may have more of a need for a better air filter.
 

dirt bike dave

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#6
On many engines you can certainly increase the flow of the intake tract while retaining the stock valve size, cam, and throttle body.

I replaced the drop-in K&N filter with an Airaid FIPK which also uses a K&N filter on a larger, smoother tube betwen the filter and the throttle body. The Airaid eliminates the air box, and provided a more aggressive sound at full throttle, and a noticeable increase in power above 3,000 rpm. No power increase at low rpm and no more noise than stock at low throttle.

The only reason K&N filter oil would contaminate your mass flow sensor is if the filter is over oiled.
 
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#7
I bought a K&N for my '88 Bronco2 XLT.
(think it cost me about $30.00)
Used it for about 75,000 miles, then when i got my '90 Bronco2 i switched it to that one.
(about 80,000 miles so far)
I'm sure that any performance gaines are minimal, but ive saved a few bucks on replacemant air filters!! :D
 
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#8
Okay, try this...
Take a piece of paper and try to breathe through it. DOH!@!! You can't, can you??!!!!
Now take a piece of cotton gauze like the ones used for cuts and big gaping motorcycle wounds, and try to breathe through that. Hey! Big difference!
This is how your engine makes power...get the most air in and out and you will make the most power that your combination will allow.
Now, i agree with the others that if your truck is a piece of Cow Poop, then slapping on a K&N will not do anything!! It will only waste your money and make you frustrated.
You most likely will not feel 7-15 horsepower on a newer truck that makes 250-350 horsepower. But its possible to do so. Theres many other factors that attribute to that "seat of the pants" feeling.
I run a K&N filter and noticed a difference when I switched to it.
And besides, motors are designed to work efficiently (or, most efficiently) at a certain RPM. You probably wont feel "the power" all through the vehicles powerband.
But...Using a K&N will save you money in the long run and will catch more dirt and crap in the air than a normal paper filter.
So if saving money isn't "performance" (more specifically : "pocketbook performance") than I don't know what is.
Travis Rydberg
 

Danman

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#9
I put a drop in in my 96 GMC 1500. I noticed a little more throttle response and that was it. It was the first filter that I bought for the truck. It pretty dusty out here so I clean it often. It has payed for itself already. I expect that I will get many more miles out of it.
 
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#10
1997 F-150 w/4.6

I replaced my stock airbox with the K&N FiPK. It's spendy (about $200.00 online??) but I gained about 2-3 MPG and it increased the torque in the lower R's. It doesn't shift out of OD as often on the highway now.

It is quite loud from 2500-3000 rpm. I only notice it if I'm pulling a load and spend alot of time around that RPM.
 

mtngoat

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#11
I put one on my 85 CJ7 and at 7000' altitude, I noticed the difference, but not as much as advancing my timing. I run K&Ns on almost everything I ride/drive.
 
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#12
I put one in my 98 F150 w/ a 4.6 V8 in it. I noticed an increase in power, allbeit small. However, I also noticed a corresponding increase in fuel efficiency. It went up roughly 2 mpg. This was with the basic K&N filter (no fancy kits).

I'm convinced. Plus, the fact that I'll never need to replace the filter on my truck is an added benefit!! Just clean it and oil it occasionally. (Like we don't all know how to clean and oil a filter already!! LOL!)

As far as an increase in noise....I can't say....my truck was pretty darn loud before!
 
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#13
Is this logical?

I just put a K&N in my F-150. My dad said that if it flows more air it is less restrictive and thus will also allow more dirt and particles to pass through than the stock Fram type air filter. I say the gauze type with the oil actually catches more dirt than the paper type. BTW, I did not notice any real power gains. What are other opinions as far as keeping the engine air intake clean?