Less restriction = more flow

[mjoekingz28]

Hey all, I have a K&N that was in the truck when I bought it, didnt know at the time and went with an orange Fram. I spen a few minutes comparing it vs the yellow extra guard and got e plain paper one mainly because the yellow filter said it traps twice the dirt, so i thought it to be quite restrictive. But now, after looking on their website, they say their top filter is less restrictive and on the installation how-to video, they even use my type truck and engine.

So I ask, is there some kind of comparison on these air filters or do i just rely on seat-of-the-pants? I already have the plain Fram and am getting some more oil for the K&N (to hopefully get it saturated without dripping), and am planning on buying the yellow tough guard, so I will probably have enough filter for the life of the truck.

Since I dont rev my truck high, I go by the sound of the pipes and the throttle response of the torque. I figure any filter will have satisfactory filtration for regular street driving, so I will go by the aforementioned.

TIA

 

[Shannow]

Any time that you are driving your car with the throttle opening at less than wide open, the restriction in your filter is having zero effect on performance or economy.

 

[Olas]

If the filter is the bottleneck in the system the changing to a less restrictive filter will allow more air to flow.

If its a petrol engine, the throttle blade is the the restriction except at WOT when it's likely port/throat/valve, they are what you need to address to allow more flow.

Chances are, the designers used a filter that flows enough air that the car can make power at WOT, factory air boxes are a lot better designed than most give them credit for

 

[edwardh1]

I would not use a k n,
but would get the better fram
(I use Denso as I think its oem (Japanese stuff runs a long time usually)
and
they have good quality control)

 

[mjoekingz28]

I would like to agree with you all, but, on a 92 Chevy 350 that i had driven, we would turn the round air filter cover over, exposing the element, and while i cannot prove it had more torque, it definately sounded alot meaner.

 

[spasm3]

Originally Posted By: mjoekingz28
I would like to agree with you all, but, on a 92 Chevy 350 that i had driven, we would turn the round air filter cover over, exposing the element, and while i cannot prove it had more torque, it definately sounded alot meaner.


I did that on my 76 buick, had more power wide open, and you could hear the carb moan. The problem is, almost every uoa with a k+n shows more dirt.

 

[Bottom_Feeder]

More intake noise does not equal more power.

 

[spasm3]

Originally Posted By: Bottom_Feeder
More intake noise does not equal more power.


I agree, and modern intake/air filter housings are pretty optimized for noise and economy vs what was on them in the '70's.

 

[spasm3]

Originally Posted By: mjoekingz28
I would like to agree with you all, but, on a 92 Chevy 350 that i had driven, we would turn the round air filter cover over, exposing the element, and while i cannot prove it had more torque, it definately sounded alot meaner.


That would still be better than running a k/n filter.

 

[HerrStig]

Toyota used the same filter on I 4 AND V6 Camrys for a number of years. SO, either it was undersized for the 6 or oversized for the 4. Go figure.

 

[Olas]

Originally Posted By: Bottom_Feeder
More intake noise does not equal more power.


Maybe not on a correctly calibrated and operated dyno, but the ever-reliable butt dyno will certainly feel the difference! Just like how it idles smoother right after you wash and wax it..

Joking aside, more intake noise doesn't always mean more power, sometimes it does. Wether you talk about peak numbers or AUC you can't just make a generalisation like that.

A pod filter or CAI will make more noise for sure but power could go up or down on innumerable variables, but;
Changing out your airbox, MAF, manifold and injectors for a set of ITBs will definitely make more power and probably be louder but a well thought out intake tract could muffle the intake noise to a lower level than it was from the factory.

See if you can find an industrial spec filter such as a Donaldson to fit your application - commercial/industrial stuff is a lot more stout than passenger vehicle stuff

 

[Olas]

Originally Posted By: HerrStig
Toyota used the same filter on I 4 AND V6 Camrys for a number of years. SO, either it was undersized for the 6 or oversized for the 4. Go figure.


Over the years and through various permutations of crank, rod, pistons and head, VW have used the same filter on 1.3 upto 1.8 litres but was originally designed for the 1457cc motor. They obviously build a lot of excess capacity into these filters at design stage and it's cheaper/quicker/easier to set up the tooling and machining to produce 1 filter to fit the platform, rather than have several different production lines to cover different models in the same range. It's actually one of the few times engineering and accounting agree with each other.

 

[CT8]

Less restriction = more flow,,,, how much area does the filter have?

 

[bullwinkle]

Originally Posted By: spasm3
Originally Posted By: mjoekingz28
I would like to agree with you all, but, on a 92 Chevy 350 that i had driven, we would turn the round air filter cover over, exposing the element, and while i cannot prove it had more torque, it definately sounded alot meaner.


I did that on my 76 buick, had more power wide open, and you could hear the carb moan. The problem is, almost every uoa with a k+n shows more dirt.
Did that with my old '68 Impala SS, running the 327/300 HP Quadrajet-brother drove it, the local PD pulled him over for having a loud CARBURETOR! The joys of growing up in a small town! To the OP, I ran a 2 stage foam/paper Purolator AF on the '06 Ram in my sig, it would actually make it "roll coal" (with stock programming) & pull down the restriction gauge. S&B filter fixed that problem.

 

[901Memphis]

Do yourself a favor and toss the K&N in the trash. Keep using the paper filter and don't disturb it until it reaches the manufacturers filter interval.

 

[FFeng7]

Originally Posted By: HerrStig
Toyota used the same filter on I 4 AND V6 Camrys for a number of years. SO, either it was undersized for the 6 or oversized for the 4. Go figure.


Dodge also did this on the 2002 Dakota. They spec the same air filter for the 2.5 4 cylinder, 3.9 V6, 4.7 V8, and the 5.9 V8. If the filter was sized for the 5.9 then it's unlikely it would be much of a restriction at all on the 2.5.

 

[mjoekingz28]

I think it is akin to furnace filters, not max airflow. On my home acor heat and on a car's cabin filter you can take them out and blatently experience increased airflow. Sure the filter could have flowed more air if the fan was bigger but it breathes easier at, say, half capacity. It is like i can breathe heavily and strained thru one nostril, or easily and relaxed thru both.


I dont really care about top end max hp, but idle to, say 3500, good fuel economy and a good sounding exhaust. As for the exhaust, it just seems you can push the pedal that extra bit and get extra power versus getting no extra power. That really bugged me with my old Z28. At like a third of WOT was all she had, the second half or so of the as pedal did nothing. It just kind of kills the fun of the driving experience- which is what it is all about, right.

 

[Ken2]

Quote:
Any time that you are driving your car with the throttle opening at less than wide open, the restriction in your filter is having zero effect on performance or economy.
Quote:
If the filter is the bottleneck in the system the changing to a less restrictive filter will allow more air to flow.

If its a petrol engine, the throttle blade is the the restriction except at WOT when it's likely port/throat/valve, they are what you need to address to allow more flow.

EXACTLY!

The engine is an air pump. It pumps air past the throttle plate which is always a restriction except at wide open. As an air pump, it pumps more when it runs faster. So...if the stock air filter is actually a significant restriction (which it ain't), then a so-called less restrictive air filter would only be effective at wide open throttle AND high rpms.

Use a K&N or don't. It doesn't matter. Some leak some dirt through (my Volvo did). Some don't leak dirt. IT WILL NOT IMPROVE GAS MILEAGE.

 

[badtlc]

any time you can reduce restriction, even in the air filter, it reduces the force required to pump air into the engine. It is simple physics. Whether or not those gains in efficiency are perceptible at low RPMs/throttle is a different story, but it is there regardless.

 

[Shannow]

Originally Posted By: badtlc
any time you can reduce restriction, even in the air filter, it reduces the force required to pump air into the engine. It is simple physics. Whether or not those gains in efficiency are perceptible at low RPMs/throttle is a different story, but it is there regardless.


It's not...reduce the restriction in the air filter, you have the throttle plate more closed, to control engine load speed...it's simple physics.