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K&N Air Filters, Good or Bad?


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I've had a K&N 14" x 4" tall filter on my Chevelle for years now. I've cleaned it several times and reoiled it. I was looking at it and adjusting the carb the other day and it just seems to me that filter is so heavy compared to a paper one. I just think the oil would restrict flow compared to paper. Or maybe I just put on too much oil. I put the paper one in and went for a drive and it seems to rev up quicker, but hard to tell. It was at 7200 before I knew it in low gear. Don't want to go that high too often.¬†ūü§≠

Back when I had an F250 with a 7.3 diesel I had a K&N in there and the Ford dealer took it out and dumped it. They said they did more damage to engines than anything. 

Opinions please? 

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If you were fighting super dusty conditions like a race application and looking for a way to reuse rather than replace then ok.

In my opinion they are marketed because they can be sold and shipped in a box to fellas looking for something to buy.

Just a paper element for street use, if an oiled element was way better they would come on all the expensive performance vehicles from the factory.............

I don't see how they would tear anything up thou

 

 

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Junk. I had two of them on turbo charged vehicles, and they would let the dust go through when they start to get dry. Also, on my old Cummins that was modded out, it would actually start to suck the oil through into the intake pipe. 

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My FIL is a filter design engineer. He says without question that a paper filter is better. Mechanic friend throws every K&N away he can. Says they will dust a turbo and at the very least allow more dirt into the engine than paper. A dirty paper filter is more efficient than a new one also if you put them on a test stand side by side. 

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11 minutes ago, Sledgehammer said:

My FIL is a filter design engineer. He says without question that a paper filter is better. Mechanic friend throws every K&N away he can. Says they will dust a turbo and at the very least allow more dirt into the engine than paper. A dirty paper filter is more efficient than a new one also if you put them on a test stand side by side. 

I’ve heard the exact same thing!! 

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I have run them in two of  my trucks I use for wheeling both later model gas they have an advantage In applications were they may get wet.

The 99 I have has 250K plus still runs the same 1/4 mile time as tested by road and track and the intake track is clean. 

I run a foam pre filter as well.

On a carbureted engine yes they are trouble some with the mixture, fuel injection is going to compensate for the them.

If you run them it is best to leave them for a longer period they work better with a coating of dust.

For ease of maintenance on street drive stuff the paper disposable are the way to go. 

And I have seen dusted motors that ran stock filters usually from leaky intercooler couplings. 

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48 minutes ago, jeeper61 said:

I have run them in two of  my trucks I use for wheeling both later model gas they have an advantage In applications were they may get wet.

The 99 I have has 250K plus still runs the same 1/4 mile time as tested by road and track and the intake track is clean. 

I run a foam pre filter as well.

On a carbureted engine yes they are trouble some with the mixture, fuel injection is going to compensate for the them.

If you run them it is best to leave them for a longer period they work better with a coating of dust.

For ease of maintenance on street drive stuff the paper disposable are the way to go. 

And I have seen dusted motors that ran stock filters usually from leaky intercooler couplings. 

Just curious, if an intercooler is in place, there must be pressurized air from a turbo. How does a positive pressure suck in dust?

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6 minutes ago, arizonian said:

Just curious, if an intercooler is in place, there must be pressurized air from a turbo. How does a positive pressure suck in dust?

Ever seen a radiator hose that weeps at the connection to radiator?

Not enough to cause a major malfunction but enough to let air pass in both directions 

A turbo motor not always building boost they also build vacuum when off the throttle and can suck in dust 

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Just now, jeeper61 said:

Ever seen a radiator hose that weeps at the connection to radiator?

Not enough to cause a major malfunction but enough to let air pass in both directions 

Weeping implies that fluid is leaking out, which is what positive pressure will do.

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26 minutes ago, arizonian said:

Weeping implies that fluid is leaking out, which is what positive pressure will do.

A turbo motor not always building boost they also build vacuum when off the throttle and can suck in dust 

A cracked intercooler or turbo pipes can do the same not enough of a leak to cause a low boost condition but enough to suck in the dust

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I had a K&N in my Jeep and it seemed to work Ok, but It wasn't any better than a paper. The oil is supposed to attract & hold onto the dirt, why you can't use to much or to little. I found them to be a hassle in the long term over the dry paper. Issue was when time to clean you had to wash out the dirt, dry, then re-oil. Paper every so often you simply blew the dirt off from the inside out, & stuck it back on. Easy squeezy.  Maybe the best old school filters were the old oil bath & metal mesh, but even those were a pain to clean, hence the advent of the dry paper.

 

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I WILL NOT use a K&N or any other such type filter. I used to have a pair of them on my go kart which has a sled engine on it. The filters sat on a pair of 90 rubber elbows, one per carb. Between oil from the filters and oil from the 2 stroke mix getting blown back out of the carbs by reversion, there was a coating of oil on the inside of those 90* elbows. On the oil was a coating of dust. An oiled pleated cotton filter like that does not stop all the dirt. 

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4 hours ago, jeeper61 said:

The 99 I have has 250K plus still runs the same 1/4 mile time as tested by road and track and the intake track is clean. 

Whats your quarter mile time? I am down to about a 1:45 quarter mile in my 95‚Ķ maybe I should try oneūü§Ē

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I have never been a fan, my dad had one on an 01’ GMC with a 5.7 vortec, i spent a lot of time cleaning, oiling and it never realized any mileage gain or noticeable horsepower gain. Probably if used in conjunction with a decent cold air intake you could see some gain, but I don’t think you can credit the filter. 

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Had one in my '99 Dodge Cummins. Sucked all the oil out and ruined a lot of MAP sensors. The solution for the Dodge is to loosen the clamp on the hose going to the air box, rip it forcefully from the fender, and clamp an AF19023 to the hose. 

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I had one on my S10 way back when because I thought they were better and would increase fuel mileage.  Looking back it was a waste of $$ and I don't bother with em now.  Stock filter box and change the filter yearly at least is the way I go now. 

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They will get oil on the mass airflow sensor and screw up mileage and cause drivability problems. Waste of money. 

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1 hour ago, vtfireman85 said:

Whats your quarter mile time?

16.1 - 300HP Cast iron headed LS 6.0 Standard Cab 8 ft bed 4x4 I think it tips the scale at 5600

K&N been in it since 10K got 250K now I run a foam pre filter to keep the trash out of the bottom of the air box 

As others have said they are pain to clean 

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1 hour ago, Wi Ih said:

They will get oil on the mass airflow sensor and screw up mileage and cause drivability problems. Waste of money. 

X 2¬†¬†ūüė†ūüĎé

Mike

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I have one on the jeep, runs fine and cleans easy, had one in the stock housing in the ram, when I installed the new AFE intake manifold I went with a stage 2 AFE cold air cone intake, this time I went dry, both worked fine, but I liked the dry better.

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5 hours ago, jeeper61 said:

A turbo motor not always building boost they also build vacuum when off the throttle and can suck in dust 

A cracked intercooler or turbo pipes can do the same not enough of a leak to cause a low boost condition but enough to suck in the dust

Sorry, but I have to agree with some of that, but disagree with most of it. Movement of fluid or air from one side to the other is from a change of pressure. Yes, you can have a crack that will not cause it to be low boost, but boost is positive pressure. Positive pressure doesn't have a vacuum, so, no it's not going to "suck" in air or dust unless it is at a negative psi, which is the difference in pressure at atmospheric pressure. Positive psi, positive pressure, negative "psi" (to keep terms from getting too confusing, normal to actually measure in inches or Mercury or mbar). So, to have air movement in, there must be a higher atmospheric pressure and a negative pressure or vacuum in your intake, hence the reason, pressure change, air enters the engine. Positive pressure will push dust or dirt out. Yes, although you are correct that often times, at idle or no load condition, there can be a slight vacuum on the intake of a turbo charged engine and suck in dust. 

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7 hours ago, MinnesotaFarmall said:

Positive pressure doesn't have a vacuum, so, no it's not going to "suck" in air or dust unless it is at a negative psi,

One of my turbo cars at ide just a little negative pressure  

Charge piping was dusted after the crack in the intercooler 

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