Does Size Matter?

A

abnovak

New Member

Jul 21, 2002

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Jul 8, 2004

#1

• Jul 8, 2004

• #1

Have a friend who has a 351 with a 14" K&N aircleaner but he likes the smaller 9" chrome air cleaner better. Will he loose performance going to a smaller size?

 

TheWolf

New Member

Jan 13, 2003

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NC

Jul 8, 2004

#2

• Jul 8, 2004

• #2

If they're both the same type of filter, I don't think there'd be much difference at all. At least not that you could tell.

 

DarkBuddha

Founding Member

Dec 11, 2001

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Seattle & Tampa

Jul 8, 2004

#3

• Jul 8, 2004

• #3

I doubt he'll notice any loss of performance, but theoretically, it is possible if the smaller air cleaner causes enough restriction to choke the carb. The 14" air cleaner provides for more surface, thus providing less restriction to air to flow to the carb. The formula for the circumference is 2pir so to get the area for each air cleaner, multiply the circumference by the height of the air cleaner. For example:

area for the 14" air cleaner =
2
* 3.14159
* 7" (half of diameter of 14")
* 3" (example air clean height)
= 131.94678" of area

area for the 9" air cleaner =
2
* 3.14159
* 4.5" (half of diameter of 14")
* 3" (example air clean height)
= 84.82293" of area

But, will he notice any performance loss? Probably not since it's doubtful the 9" air cleaner will cause enough restriction. Probably more consequential is that the K&N will outflow a normal paper element (which is a bigger restriction), so if the 9" is a paper element air cleaner, I say stick with the 14" K&N.

Hope this helps.

 

1

1969mach1351

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Apr 18, 2003

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Sacramento, CA

Jul 8, 2004

#4

• Jul 8, 2004

• #4

A 351 with a redline of 6000 RPM needs about 101 cubic inches of filter area. Like DarkBuddha said 14"x3" has 131 and the 9"x3" has 84. If he wants a 9" he will have to go with a 9"x4" which is 113 cubic inches.

 

WRXracer

New Member

Feb 28, 2003

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Jul 8, 2004

#5

• Jul 8, 2004

• #5

ok

ill ask my lady tonight if size matters..

 

D

D.Hearne

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Sep 29, 2000

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south louisiana

Jul 8, 2004

#6

• Jul 8, 2004

• #6

If he goes with a K&N 9" diameter filter, then he'll lose nothing. I saw a test where they compared engine performance to filter size using K&N's and even with the tiny 4" filter, nothing really changed much as HP goes. There wasn't 10 HP difference from the smallest to the largest K&N. I believe the test motor was a Chevy 350.

 

67coupe351w

New Member

Jan 31, 2004

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Portland, OR

Jul 8, 2004

#7

• Jul 8, 2004

• #7

Arent air filters rated in CFM? As long as the CFM is as big as your carb there wouldnt be any problem.

 

Route666

Active Member

Aug 16, 2003

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Brisbane, Australia

Jul 8, 2004

#8

• Jul 8, 2004

• #8

1969mach1351 said:

cubic inches of filter area.

Click to expand...

Ahhh cubic inches are volume not area. Did you mean sq inches?

 

1

1969mach1351

Member

Apr 18, 2003

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Sacramento, CA

Jul 8, 2004

#9

• Jul 8, 2004

• #9

oops Thanks for pointing that out Route666.

 

Route666

Active Member

Aug 16, 2003

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Brisbane, Australia

Jul 8, 2004

#10

• Jul 8, 2004

• #10

No wukkas!

 

TireSmoknWindsr

Founding Member

Sep 12, 2002

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Half past whup'n some import's ass

Jul 8, 2004

#11

• Jul 8, 2004

• #11

After reading this thread....my head hurts

 

6

65straightsick

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Jun 4, 2004

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Montgomery, AL

Jul 8, 2004

#12

• Jul 8, 2004

• #12

Welcome back to school