K&N filters more restrictive than paper??

[metroplex]

I've seen the flow testing that showed K&N filters outflowed paper filters, but I've personally ran into 2 situations where it seems the K&N panel filters are more restrictive than paper filters.

One is a 2000 Crown Vic. My dad drives it all the time, so I decided to throw in a new K&N panel filter I had gotten awhile ago. I never told him this and let him drive it for a few days. He just told me that for the past few days, the car felt like it had no power and it would stumble badly on idle. I swapped out the air filter for his original paper filter, and the problems went away.

The next situation is my 2007 Mustang GT. I threw in a new K&N panel filter and noticed the engine only flows a max of about 31 #/min, and whenever I clutched in or came to a stop in neutral, the engine RPMs would drop very very low to about 500 RPM and it sounded like the engine would stall out. I also didn't hear as much exhaust burble (FR500S mufflers) or even snapping when free-revving. I replaced the K&N with a paper filter and the snapping is now back, I hear a lot more burble, and the engine RPMs only drop to the commanded RPM when I clutch in or come to a stop in neutral.

I didn't notice any of these things with my EcoBoost SHO with the K&N panel filter. But I've heard more than once that turbochargers will flow as much air as it needs - whatever that means?? Wouldn't there be a bigger pressure drop at the same flow rate if the filter was a restriction? Wouldn't that make the turbo work harder and create more heat?

Any thoughts on this? Am I alone with these observations? Those are two N/A Ford modular V8s that reacted rather negatively to new K&N panel filters and it wasn't because of MAF contamination.

 

[Linctex]

I don't think it's a restriction.... most any air filter, even one nearly plugged - - will flow plenty of air at idle, because CFM is the lowest. Restriction doesn't exhibit until higher RPM's.

Maybe there's some weird turbulence occurring near the MAF?
That would explain your father's "stumble badly on idle"

 

[Langanobob]

It!s hard not to over oil K&N during the initial installation or after cleaning. It takes awhile for the excess oil and resultant restriction to clear. I suppose that could possibly be the cause of the poor performance.

 

[nyumski]

over oil in ur K&N, just re-clean then apply very thin oil and let the oil spread itself. after that clean ur MAF sensor with CRC MAF sensor cleaner (for safety precautions)

over oil will cause MAF malfunction in the future.

 

[03cvpi]

It could also be too less restrictive. I put one on a 92 chevy 1 ton truck with a 454 and it ran awful. Would almost die when coming to a stop and stumbled on acceleration. Put the paper element back in and it worked fine. After trying different things to get it to run right, I finally decided to use a manometer on the the filter. Drilled a hole in the air cleaner cover on either side of the filter and plugged in the manometer. the paper element was rated for something like 480cfm and I couldn't find a rating for the K&N wet filter. At 4k rpm the paper filter pulled about 2.5 inches and the K&N pulled about 0.3 inches. Best guess was lack of restriction caused turbulence in the incoming airflow and an uneven mixture to the cylinders. I went back to the paper element. Note: uses a MAP sensor not MAF

My old boss put one on his Ram V10 and apart from making it sound like the truck had a turbo charger on acceleration and a small drop in gas mileage, ran just fine. According to him, no perceived performance increase. He went back to a paper element after he got tire of the whistle on acceleration.

 

[cashmoney]

Install a high quality modern paper element air filter. Oiled air filters are basically obsolete 1930s technology hyped by multi-million dollar marketing campaigns.

 

[philipp10]

Originally Posted By: 03cvpi
It could also be too less restrictive. I put one on a 92 chevy 1 ton truck with a 454 and it ran awful. Would almost die when coming to a stop and stumbled on acceleration. Put the paper element back in and it worked fine. After trying different things to get it to run right, I finally decided to use a manometer on the the filter. Drilled a hole in the air cleaner cover on either side of the filter and plugged in the manometer. the paper element was rated for something like 480cfm and I couldn't find a rating for the K&N wet filter. At 4k rpm the paper filter pulled about 2.5 inches and the K&N pulled about 0.3 inches. Best guess was lack of restriction caused turbulence in the incoming airflow and an uneven mixture to the cylinders. I went back to the paper element. Note: uses a MAP sensor not MAF

My old boss put one on his Ram V10 and apart from making it sound like the truck had a turbo charger on acceleration and a small drop in gas mileage, ran just fine. According to him, no perceived performance increase. He went back to a paper element after he got tire of the whistle on acceleration.


nice job but doesn't K and N publish these specs somewhere?

 

[Quantico]

Install a high quality modern paper element air filter. Oiled air filters are basically obsolete 1930s technology hyped by multi-million dollar marketing campaigns.

Well said