Why not just get a larger filter surface area than a K&N?

[soccerballtux]

Guaranteed good filtering and you get the lower resistance higher flow. Ok it doesn't fit in the stock airbox but at least you get good filtering.

 

[monkeydelmagico]

yes but only for the middle part otherwise it could be a big no depending on how good the filtered air smells

 

[JCH13]

I'm not sure of the point in asking this question... the reason to not use a larger filter element is that it won't fit and generally won't improve performance. Though a denser pleating pattern will result in more filter surface area (to a point) and will still fit in the stock airbox.

 

[WilliamM2]

The stock filter is capable of more flow than needed, why go bigger, or K&N. I know my ZX-11 lost power with a K&N, it was poorly designed, and had less surface area than stock. Here's a pic:

http://www.ebay.com/itm/K-N-FILTER-...JA-ZZR1100-ZZR1200-SEE-APP-LIST-/321096851811

On the original the frame is only 1/4" wide, the K&N frame takes up 30-40% of the surface area.

I don't think they really do much R&D, just make it fit.

 

[soccerballtux]

I'm not sure of the point in asking this question... the reason to not use a larger filter element is that it won't fit and generally won't improve performance. Though a denser pleating pattern will result in more filter surface area (to a point) and will still fit in the stock airbox.

You can model a lot of things with electrical engineering in this case the filter media is a resistor, and having more of it is more resistance in parallel, reducing the total resistance.
So I don't know why you would say it wouldn't improve performance.

 

[soccerballtux]

The stock filter is capable of more flow than needed, why go bigger, or K&N. I know my ZX-11 lost power with a K&N, it was poorly designed, and had less surface area than stock. Here's a pic:

http://www.ebay.com/itm/K-N-FILTER-...JA-ZZR1100-ZZR1200-SEE-APP-LIST-/321096851811

On the original the frame is only 1/4" wide, the K&N frame takes up 30-40% of the surface area.

I don't think they really do much R&D, just make it fit.

Yeah I don't know why I bought one. It doesn't filter anything

 

[jlee]

You can model a lot of things with electrical engineering in this case the filter media is a resistor, and having more of it is more resistance in parallel, reducing the total resistance.
So I don't know why you would say it wouldn't improve performance.

Most cars aren't really limited by their air filter. 600whp forced induction engine? Sure. 90whp econobox? Nooope.

 

[JCH13]

You can model a lot of things with electrical engineering in this case the filter media is a resistor, and having more of it is more resistance in parallel, reducing the total resistance.
So I don't know why you would say it wouldn't improve performance.

To take your resistor model a step further...

The filter is a resistor. The airbox is a resistor. The intake tubing is a resistor. Any sensor protrusions into the air-stream are resistors. The throttle plate is a resistor. The intake plenum is a resistor. The intake runners are resistors. The intake ports are resistors. The intake valves are resistors.

That's a lot of resistors. Putting a larger or freer-flowing air filter on does in theory improve performance, but its improving one small portion of a large resistor network.

There are some dyno tests showing an initial power gain with a K&N filter (or other 'performanc'e air filters), there are other tests showing power losses with K&N air filters. All of these tests show power changes within a few percent of each other, which in some cases is within the measurement error of the dyno's implementation and operation.

See this article: http://forums.nicoclub.com/debunking-the-k-n-myth-why-oem-is-better-t180100.html

Go to the last plot, showing pressure loss vs flow rate. At the highest tested flow rate the most restrictive filter shows around 3in of water loss, the least restrictive shows around 1in of water loss, both at ~350CFM (roughly equivalent to 240hp worth of air). The difference, 2in of water, is 0.5kPa. Less than 0.5% of atmospheric pressure. The overall effect will depend upon a specific engine's design, but you're probably looking at 0.5%-1% improvement in pressure delivery to the intake.

Edit: some specific dyno testing of air filters.

Note that all results in this one are within 1-2% of each other, and a K&N had more power than no air filter. Curious.
http://www.mustangsandmore.com/ubb/Forum1/HTML/016727.html

I like this post because it shows the wide variance between back-to-back dyno runs.
http://my.is/forums/f136/dyno-tested-k-n-typhoon-intake-vs-stock-airbox-vs-diy-intake-mod-413122/

 

[Meghan54]

I think a lot of people would be surprised to find their stock air box in their vehicles aren't very restrictive, despite claims to the contrary from certain companies. Think about it, car manufacturers are not only in a horsepower race but also a fuel economy "race", hence it'd be in the best interests to design air boxes to be as free flowing as possible.

I tend to think the major restriction is in the air tube between the air box and manifold, which typically will include some sort of resonator to quiet the drone a wide open system can create.

For instance, Black Bear Performance, a tuner specific to GM trucks, dyno'd several CAI systems, an Airaid MIT and the stock setup on a 2006(?) GM Silverado with the 5.3L V-8. It has a bit over 100k miles on the clock and bone stock.

The Airaid MIT, which is just a replacement tube that fits between the stock air box and manifold but smooths out the channel and drops off the resonator, produced the same hp and torque increases that the CAI's produced or bettered them. The CAI's included the K&N, Volante, among others.

Just showed the stock air box in this truck was not the limiting factor in moving air into the engine. I'd tend to think the air boxes, esp. any vehicle even slightly skewed towards performance, would probably show the same results....the stock air box probably isn't the hindrance to air flow. Of course, this is just extrapolating a single data point, but if a truck's stock air box showed it could flow up to 750cfm without compromising performance compared to CAI air fliters like K&N, I'd imagine "decent" cars would be even better tuned out of the factory for good air flow.

 

[Yuriman]

A restrictive filter might hurt max (WOT) HP but will basically never hurt economy on a car with a traditional butterfly valve throttle plate. Personally, I'll take a 1-2HP hit (if that) to keep more dust and crud out of my engine.

 

[soccerballtux]

To take your resistor model a step further...

The filter is a resistor. The airbox is a resistor. The intake tubing is a resistor. Any sensor protrusions into the air-stream are resistors. The throttle plate is a resistor. The intake plenum is a resistor. The intake runners are resistors. The intake ports are resistors. The intake valves are resistors.

That's a lot of resistors. Putting a larger or freer-flowing air filter on does in theory improve performance, but its improving one small portion of a large resistor network.

There are some dyno tests showing an initial power gain with a K&N filter (or other 'performanc'e air filters), there are other tests showing power losses with K&N air filters. All of these tests show power changes within a few percent of each other, which in some cases is within the measurement error of the dyno's implementation and operation.

See this article: http://forums.nicoclub.com/debunking-the-k-n-myth-why-oem-is-better-t180100.html

Go to the last plot, showing pressure loss vs flow rate. At the highest tested flow rate the most restrictive filter shows around 3in of water loss, the least restrictive shows around 1in of water loss, both at ~350CFM (roughly equivalent to 240hp worth of air). The difference, 2in of water, is 0.5kPa. Less than 0.5% of atmospheric pressure. The overall effect will depend upon a specific engine's design, but you're probably looking at 0.5%-1% improvement in pressure delivery to the intake.

Edit: some specific dyno testing of air filters.

Note that all results in this one are within 1-2% of each other, and a K&N had more power than no air filter. Curious.
http://www.mustangsandmore.com/ubb/Forum1/HTML/016727.html

I like this post because it shows the wide variance between back-to-back dyno runs.
http://my.is/forums/f136/dyno-tested-k-n-typhoon-intake-vs-stock-airbox-vs-diy-intake-mod-413122/

that is curious.
good links. I'll have to check out the filter test methodology, why not 1" on less restrictive 3" on more restrictive? It's the water column on the filter vs gravity no?

the throttle plate is a potentiometer and
oh you took out turbo I was going to say ... inductor
sorry I just took that as a challenge

I think a lot of people would be surprised to find their stock air box in their vehicles aren't very restrictive, despite claims to the contrary from certain companies. Think about it, car manufacturers are not only in a horsepower race but also a fuel economy "race", hence it'd be in the best interests to design air boxes to be as free flowing as possible.

I tend to think the major restriction is in the air tube between the air box and manifold, which typically will include some sort of resonator to quiet the drone a wide open system can create.

For instance, Black Bear Performance, a tuner specific to GM trucks, dyno'd several CAI systems, an Airaid MIT and the stock setup on a 2006(?) GM Silverado with the 5.3L V-8. It has a bit over 100k miles on the clock and bone stock.

The Airaid MIT, which is just a replacement tube that fits between the stock air box and manifold but smooths out the channel and drops off the resonator, produced the same hp and torque increases that the CAI's produced or bettered them. The CAI's included the K&N, Volante, among others.

Just showed the stock air box in this truck was not the limiting factor in moving air into the engine. I'd tend to think the air boxes, esp. any vehicle even slightly skewed towards performance, would probably show the same results....the stock air box probably isn't the hindrance to air flow. Of course, this is just extrapolating a single data point, but if a truck's stock air box showed it could flow up to 750cfm without compromising performance compared to CAI air fliters like K&N, I'd imagine "decent" cars would be even better tuned out of the factory for good air flow.

well.
I can say that sawing off the airbox on my sv1000 motorcycle gave me more power. I think it was running rich.


also I have to say that I felt a bit more torque on the top end of my Scion tC with the K&N. The drop off after the power band wasn't as bad.
Not enough to use it though.

 

[JCH13]

the most restrictive filter shows around 3in of water loss, the least restrictive shows around 1in of water loss,

that is curious.
good links. I'll have to check out the filter test methodology, why not 1" on less restrictive 3" on more restrictive? It's the water column on the filter vs gravity no?

Bro, do you even read?

:awe:

 

[soccerballtux]

wrote that backwards. What else would it be?

 

[JCH13]

wrote that backwards. What else would it be?

I'm just giving you a hard time

 

[soccerballtux]

I'm just giving you a hard time

hes messin with me ima show him a thing or two beetter bring a watch bro cause its gonna be a long day know what im sayin

 

[Sidekicknichola]

I'm and engineer for filter technology company... we literately have a hand in all areas of filtration, including automotive air filters.

Like others have said, everything between ambient air and the point of use is a resistor, you also have the issue of "speeding" up the air (hence the use of turbos / superchargers / etc). Another big hurdle is how most auto air filters work... most auto applications have the air entering the box and to pass through the filter and continue on downstream requires a 90* turn and that is turbulent as shit...

Our company has a filter (IP protected) that was developed for the military and currently is used a very select few consumer grade vehicle... the benefits include removing the 90* turn, WAAAY more filter media in terms of ft^2 used to make it - in a much smaller package (I think was the OP's purpose of the thread), cleanable (can be automated - used on tanks in the middle east), and provides a much better clean to dirty side separation than an standard "pleated" filter.

You can sort of see from this photo how there are lots of "flutes" ... so the air comes in and just has to shift up or down a row / column to be filtered and exits the opposite end, so the air barely changes direction resulting in a much smoother flow.

Also keep in mind your air filter is XXX% efficient when you put it in your vehicle but once dust / dirt hits it, it gets much more efficient very quickly. A "dust cake" can significantly improve your filter's efficiency but will cause a slightly higher change in inches of wG, but for 99.9% of applications is not noticeable until the filter is just "plugged"

 

[soccerballtux]

wow, that must be cheap to make. Grats on the patent I wouldn't have thought of that.

 

[Jimzz]

also I have to say that I felt a bit more torque on the top end of my Scion tC with the K&N. The drop off after the power band wasn't as bad.
Not enough to use it though.

What dyno was that, BUTT Dyno?

You did not feel any performance due to a air filter. Placebo affect i.e. all in your head.

 

[Raizinman]

What would happen if you removed the air filter and the tube to the air filter. So basically you are running the vehicle, bare naked throttle body. Heck, with no restriction, no air filter, I would estimate probably 20% more horsepower and 30% better gas mileage. Right?! Nope.

Even at WOT on a stock car you will not encounter any restrictions. The ONLY way to test this is to attach a vacuum gauge in the tube between the throttle body and air filter. At WOT if you see a vacuum in this tube you have a restriction. If not, no restriction. No need to guess.

 

[JCH13]

What would happen if you removed the air filter and the tube to the air filter. So basically you are running the vehicle, bare naked throttle body. Heck, with no restriction, no air filter, I would estimate probably 20% more horsepower and 30% better gas mileage. Right?! Nope.

Even at WOT on a stock car you will not encounter any restrictions. The ONLY way to test this is to attach a vacuum gauge in the tube between the throttle body and air filter. At WOT if you see a vacuum in this tube you have a restriction. If not, no restriction. No need to guess.

Any flow through any plumbing creates a pressure differential; some like to think of it as the pressure differential causing the flow. One will pretty much always measure a pressure difference between two points in an intake, with few exceptions. Is there a restriction? Yes. Does it make any detectable difference? Probably not.

 

[Raizinman]

Does it make any detectable difference? Probably not.

Why guess? Probably means you don't know. Lots of people on this forum don't know. The only way to really know is to attach your vacuum gauge in the tube between the air filter and throttle body. No vacuum between the two point mean no restriction. Not probably, not maybe, not in theory.

 

[JCH13]

Why guess? Probably means you don't know. Lots of people on this forum don't know. The only way to really know is to attach your vacuum gauge in the tube between the air filter and throttle body. No vacuum between the two point mean no restriction. Not probably, not maybe, not in theory.

You aren't understanding my point, so I will repeat myself: that vacuum gauge will ALWAYS show losses while the engine is running.

 

[Raizinman]

You aren't understanding my point, so I will repeat myself: that vacuum gauge will ALWAYS show losses while the engine is running.

With a new air filter, a vacuum gauge will not show any vacuum when hooked up between the air filter and throttle body.

A cranking engine will develop about 5 inches of vacuum. If the air filter is heavily restricted, you could have as much as 15 inches of vacuum. The engine will be sucking air hard to get air through the air filter and this will cause a vacuum in the tube between the air filter and throttle body. This is auto mechanics 101. Diesel air filters have had service indicator (vacuum type gauges) mounted in their air cleaner for many years.

Heck, even on the K&N air filter site http://www.knfilters.com/filter_facts.aspx?pkid=1435283&rw=2 they talk about the maximum amount of vacuum their air filters can sustain, which happens to be 15 inches of vacuum.

FROM THE K&N SITE:
"The proper way to determine when an air filter needs service is with an air restriction gauge. Such a device is commonly used on heavy duty trucks and construction equipment. A restriction gauge, measures the pressure differential inside and outside the filter and gives the information in different forms of measurement. As the filter collects more and more dirt, the restriction value increases. At a predetermined point or rate of restriction, the filter is serviced. The maximum allowable restriction for a K&N Filtercharger is 15" of vacuum (water). If the restriction is allowed to go higher, the filter media might become so restricted that the element could distort allowing dirty air to bypass the filter and enter the engine."

 

[JCH13]

With a new air filter, a vacuum gauge will not show any vacuum when hooked up between the air filter and throttle body.

Then you need a more sensitive vacuum gauge. All fluid flow is correlated to a pressure differential. End of story.

A cranking engine will develop about 5 inches of vacuum. If the air filter is heavily restricted, you could have as much as 15 inches of vacuum. The engine will be sucking air hard to get air through the air filter and this will cause a vacuum in the tube between the air filter and throttle body. This is auto mechanics 101. Diesel air filters have had service indicator (vacuum type gauges) mounted in their air cleaner for many years.

Heck, even on the K&N air filter site http://www.knfilters.com/filter_facts.aspx?pkid=1435283&rw=2 they talk about the maximum amount of vacuum their air filters can sustain, which happens to be 15 inches of vacuum.

FROM THE K&N SITE:
"The proper way to determine when an air filter needs service is with an air restriction gauge. Such a device is commonly used on heavy duty trucks and construction equipment. A restriction gauge, measures the pressure differential inside and outside the filter and gives the information in different forms of measurement. As the filter collects more and more dirt, the restriction value increases. At a predetermined point or rate of restriction, the filter is serviced. The maximum allowable restriction for a K&N Filtercharger is 15" of vacuum (water). If the restriction is allowed to go higher, the filter media might become so restricted that the element could distort allowing dirty air to bypass the filter and enter the engine."

From what you describe I am picturing a vacuum gauge (more specifically a differential pressure gauge) where one end is connected just downstream of the air filter, and one end is connected adjacent to the throttle body. This will measure the pressure losses through the intake and has nothing to do with the filter.

K&N's description is of a basic test, as you so condescendingly point out. But this is different than the test you describe in that the pressure difference is measured from just downstream on the filter to ambient air. This obviously is a good indication of filter health. But, again, this measurement will always show a pressure loss, good filter or bad, assuming a properly functioning gauge.

I'll note this test again: http://www.mustangsandmore.com/ubb/Forum1/HTML/016727.html

Filter vs no filter yielded a power difference of 1-2HP on a 200+hp car. I don't think anyone, ever, is going to notice a 1% HP fluctuation. One will see larger HP fluctuations with ambient temperatures and humidity changes over the course of a day.

I'll note this test again too, because it shows larger variations (4%) in back-to-back runs than the first test did by changing filters: http://my.is/forums/f136/dyno-tested-k-n-typhoon-intake-vs-stock-airbox-vs-diy-intake-mod-413122/

No one notices these changes, they're simply too small.