How Do You Determine The Right Size of Performance Filter For Your Car

abhik · 4th July 2008, 23:36

Hi Guys!
I am sure a lot of member have installed a K n N, Green, Pipercross etc high-flow filters on their rides and enjoying the sound of their beautiful induction roar.
But how do you determine if the air-filter that you have installed is the correct size for your vehicle? This is only reffering to conical filters.

Eg. I have a KnN RC3870 installed in my Ikon 1.6.
I installed it due to its size keeping in mind the limited space available and it looked big enough for the engine.

But i did not have any tech specs to support the above. I am sure there might be more like me out there.

So please put forward your inputs on the above.

jkdas · 4th July 2008, 23:39

In case of Green, I think its based on BHP and its printed on teh cover of it too IIRC.

khan_sultan · 5th July 2008, 11:14

In case of Green Filters, just call peter and he will do the rest -- which filter etc. When I went for Green Storm in my Palio 1.6 S10, I did exactly that.

JayD · 5th July 2008, 12:15

For green filters, i think cars lesser than 100bhp use the Green Wind while cars with 100bhp or more use the Green Storm.

gd1418 · 5th July 2008, 20:10

Korrect. That is what Arush of autopsyche advised me when I went to him get a Green installed in my Scorpio..

Quote:

Originally Posted by JayD

For green filters, i think cars lesser than 100bhp use the Green Wind while cars with 100bhp or more use the Green Storm.

nitrous · 5th July 2008, 21:02

Quote:

Originally Posted by gd1418

Korrect. That is what Arush of autopsyche advised me when I went to him get a Green installed in my Scorpio..

Did you take into account the extra volume of air a diesel would take compared to a petrol of the same bhp output?

abhik · 6th July 2008, 15:23

Well then what about KnNs, the types available is a huge list!

RedMM340 · 6th July 2008, 16:28

Quote:

Originally Posted by abhik

Hi Guys!
I am sure a lot of member have installed a K n N, Green, Pipercross etc high-flow filters on their rides and enjoying the sound of their beautiful induction roar.
But how do you determine if the air-filter that you have installed is the correct size for your vehicle? This is only reffering to conical filters.

Eg. I have a KnN RC3870 installed in my Ikon 1.6.
I installed it due to its size keeping in mind the limited space available and it looked big enough for the engine.

But i did not have any tech specs to support the above. I am sure there might be more like me out there.

So please put forward your inputs on the above.

Very simple, just stuff the biggest filter that will fit. That is the ideal size.

iceman91 · 6th July 2008, 17:10

they have a manual which gives recommendations and specs to fit the right filter.

abhik · 6th July 2008, 17:40

Quote:

Originally Posted by iceman91

they have a manual which gives recommendations and specs to fit the right filter.

But these specs were in terminology that i could'nt relate to. Can you elaborate in a simpler terminology.

abhik · 7th July 2008, 22:22

Com'on guys! Dont tell me all of us here are running KnNs on guesswork here?

I understand for Green they have an easy demarkation of specifying the BHP output of an engine to the size of the filter.

The KnN website gives you size specs of the outlet of the filter(lets assume 1.75in in dia) but there are larger filters with the same 1.75dia.

Is there anybody there who can explain how to determine the correct size of a KnN conical filter?

rks · 7th July 2008, 22:36

Quote:

Originally Posted by abhik

Com'on guys! Dont tell me all of us here are running KnNs on guesswork here?

If you bang your head once for each piece of guesswork that goes on in the business of modifications, you will have one sore head for sure. Anyway, here is one suggestion. I believe that authorized dealers do offer the K&N stock replacement filter. Get hold of the specs for that filter and then try to find out from K&N the equivalent conical filter.

iceman91 · 8th July 2008, 08:13

If maximum horsepower is the objective, the size and shape of the air filter element is paramount.

Let's first consider shape. When fitting a conventional round filter on top of the engine, such as a carburetor, central fuel injection or throttle body fuel injection, we have found a large diameter, short filter will flow more air than a small diameter, tall filter. For example, a 10-inch diameter filter 2-inches tall will flow more air than a 5-inch diameter filter that is 4-inches tall. Where space permits, the height of the filter should be between 1/5 and 1/4 of its diameter.

The shape of the filter is less important if the application calls for a remote mounted filter, which includes many late model fuel injected models. Typically these vehicles will use a flat panel filter or a conical or cylindrical shaped filter with a rubber mounting flange designed to be mounted on the end of the inlet hose.

That brings us to size.

Use the formula below to compute the minimum size filter required for your particular application. The usable portion of the filter is called the EFFECTIVE FILTERING AREA which is determined by multiplying the diameter of the filter times Pi (3.1416) times the height of the air filter in inches, then subtracting .75-inch. We subtract .75-inch to compensate for the rubber seals on each end of the element and the filter material near them since very little air flows through this area.

A = effective filtering area
CID = cubic inch displacement
RPM = revolutions per minute at maximum power

Example: A 350 CID Chevy engine with a horsepower peak at 5,500 rpm.

If you are sizing a panel filter, multiply the width of the filter area (not the rubber seal) times its length. If you are sizing a round filter, use the following formula to determine the height of the filter.

A = effective filtering area
H = height
D = outside diameter of the filter
3.14 = pi
0.75 = the rubber end caps

Example:

Referencing the K&N catalog shows the proper filter for this application would be an E-1500 which is 3.5 inches tall. Keep in mind, this is the minimum size requirement. To extend the service interval and to provide an even greater volume of air to the engine, install the largest filter that will fit in the space allotted. If the space above the engine is restrictive, perhaps a remote filter arrangement could be used to gain space.

Off-road conditions require added filter area. A filter should be sized 1-1/2 to 2 times larger than normal for any conditions that could be considered severe. In this case, the E-1500 used in our example should be replaced by an E-1120 or an E-1150. For long distance off-road events, two double-size remote mounted filters would be best.

Taken from K&N Site K&N High Performance Air Filters, Oil Filters, & Cold Air Intakes - Official K&N Engineering Site

iceman91 · 8th July 2008, 09:10

Also there is an application manual. I remember seeing one ages ago when I had the same doubts regarding sizes. It tells you which models are recommended fro your car under, replacement, performance and xtreme categories.

khan_sultan · 8th July 2008, 09:11

Quote:

Originally Posted by iceman91

....
Off-road conditions require added filter area. A filter should be sized 1-1/2 to 2 times larger than normal for any conditions that could be considered severe. .....
For long distance off-road events, two double-size remote mounted filters would be best.

Iceman, Why would that be? Is it because this setup will increase the 'low end torque' or what?

4th July 2008, 23:36	#1
abhik BHPian Join Date: Aug 2007 Location: New Delhi Posts: 848 Thanked: 12 Times View My Garage	How Do You Determine The Right Size of Performance Filter For Your Car Hi Guys! I am sure a lot of member have installed a K n N, Green, Pipercross etc high-flow filters on their rides and enjoying the sound of their beautiful induction roar. But how do you determine if the air-filter that you have installed is the correct size for your vehicle? This is only reffering to conical filters. Eg. I have a KnN RC3870 installed in my Ikon 1.6. I installed it due to its size keeping in mind the limited space available and it looked big enough for the engine. But i did not have any tech specs to support the above. I am sure there might be more like me out there. So please put forward your inputs on the above. Last edited by abhik : 4th July 2008 at 23:37.
	() Thanks

4th July 2008, 23:39	#2
jkdas Senior - BHPian Join Date: Sep 2005 Location: Thiruvananthapu Posts: 9,687 Thanked: 1,492 Times View My Garage	In case of Green, I think its based on BHP and its printed on teh cover of it too IIRC.
	() Thanks

5th July 2008, 11:14	#3
khan_sultan Distinguished - BHPian Join Date: Apr 2006 Location: Noida/Bangalore Posts: 4,925 Thanked: 5,853 Times View My Garage	In case of Green Filters, just call peter and he will do the rest -- which filter etc. When I went for Green Storm in my Palio 1.6 S10, I did exactly that.
	() Thanks

5th July 2008, 12:15	#4
JayD Senior - BHPian Join Date: Jun 2007 Location: Cochin! At last Posts: 3,236 Thanked: 2,568 Times View My Garage	For green filters, i think cars lesser than 100bhp use the Green Wind while cars with 100bhp or more use the Green Storm.
	() Thanks

6th July 2008, 15:23	#7
abhik BHPian Join Date: Aug 2007 Location: New Delhi Posts: 848 Thanked: 12 Times View My Garage	Well then what about KnNs, the types available is a huge list!
	() Thanks

6th July 2008, 17:10	#9
iceman91 Senior - BHPian Join Date: Nov 2004 Location: melbourne/banga Posts: 1,961 Thanked: 34 Times View My Garage	they have a manual which gives recommendations and specs to fit the right filter.
	() Thanks

7th July 2008, 22:22	#11
abhik BHPian Join Date: Aug 2007 Location: New Delhi Posts: 848 Thanked: 12 Times View My Garage	Com'on guys! Dont tell me all of us here are running KnNs on guesswork here? I understand for Green they have an easy demarkation of specifying the BHP output of an engine to the size of the filter. The KnN website gives you size specs of the outlet of the filter(lets assume 1.75in in dia) but there are larger filters with the same 1.75dia. Is there anybody there who can explain how to determine the correct size of a KnN conical filter? Last edited by abhik : 7th July 2008 at 22:26.
	() Thanks

8th July 2008, 08:13	#13
iceman91 Senior - BHPian Join Date: Nov 2004 Location: melbourne/banga Posts: 1,961 Thanked: 34 Times View My Garage	Filter Selection If maximum horsepower is the objective, the size and shape of the air filter element is paramount. Let's first consider shape. When fitting a conventional round filter on top of the engine, such as a carburetor, central fuel injection or throttle body fuel injection, we have found a large diameter, short filter will flow more air than a small diameter, tall filter. For example, a 10-inch diameter filter 2-inches tall will flow more air than a 5-inch diameter filter that is 4-inches tall. Where space permits, the height of the filter should be between 1/5 and 1/4 of its diameter. The shape of the filter is less important if the application calls for a remote mounted filter, which includes many late model fuel injected models. Typically these vehicles will use a flat panel filter or a conical or cylindrical shaped filter with a rubber mounting flange designed to be mounted on the end of the inlet hose. That brings us to size. Use the formula below to compute the minimum size filter required for your particular application. The usable portion of the filter is called the EFFECTIVE FILTERING AREA which is determined by multiplying the diameter of the filter times Pi (3.1416) times the height of the air filter in inches, then subtracting .75-inch. We subtract .75-inch to compensate for the rubber seals on each end of the element and the filter material near them since very little air flows through this area. A = effective filtering area CID = cubic inch displacement RPM = revolutions per minute at maximum power Example: A 350 CID Chevy engine with a horsepower peak at 5,500 rpm. If you are sizing a panel filter, multiply the width of the filter area (not the rubber seal) times its length. If you are sizing a round filter, use the following formula to determine the height of the filter. A = effective filtering area H = height D = outside diameter of the filter 3.14 = pi 0.75 = the rubber end caps Example: Referencing the K&N catalog shows the proper filter for this application would be an E-1500 which is 3.5 inches tall. Keep in mind, this is the minimum size requirement. To extend the service interval and to provide an even greater volume of air to the engine, install the largest filter that will fit in the space allotted. If the space above the engine is restrictive, perhaps a remote filter arrangement could be used to gain space. Off-road conditions require added filter area. A filter should be sized 1-1/2 to 2 times larger than normal for any conditions that could be considered severe. In this case, the E-1500 used in our example should be replaced by an E-1120 or an E-1150. For long distance off-road events, two double-size remote mounted filters would be best. Taken from K&N Site K&N High Performance Air Filters, Oil Filters, & Cold Air Intakes - Official K&N Engineering Site
	() Thanks

8th July 2008, 09:10	#14
iceman91 Senior - BHPian Join Date: Nov 2004 Location: melbourne/banga Posts: 1,961 Thanked: 34 Times View My Garage	Also there is an application manual. I remember seeing one ages ago when I had the same doubts regarding sizes. It tells you which models are recommended fro your car under, replacement, performance and xtreme categories.
	() Thanks