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Author
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Topic: Air filter ??
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 03-19-2003 12:48 PM
   
What would be the minimum air filter size for feeding a 450-500HP engine? Do any of the sub-11 second racers here use any kind of air filter? If not, what is the best way to increase natural airflow and still control air turbulence without one?DanH ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank and girdle, 5.4 H-beams, Forged slugs, TFS alum. heads, ported Stealth 8020 intake, CompCams Xtreme Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
e.t. 12.50 @ 112 mph
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Fastymz
Moderator Posts: 20708
From: Reno Nv USA M&M#1240
Registered: Apr 2001
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posted 03-20-2003 01:01 PM
I'm no where a sub 11's.But I do use a 14x5 K&N filter.------------------
SCOOP
oddly obsessed with big scoops on little Mustangs 2.26 60'S
14.9 @ 90.86MPH 65 coupe,351w,C4,Big Boss 429 hood scoop,8"3.40 TracLoc,Cragar SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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kid vishus
Gearhead Posts: 6405
From: middle of NC
Registered: Oct 2000
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posted 03-20-2003 01:06 PM
I don't run one, and haven't for years.
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steve'66
Gearhead Posts: 9489
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 03-20-2003 01:20 PM
No filter for me either,SteveW
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Fastymz
Moderator Posts: 20708
From: Reno Nv USA M&M#1240
Registered: Apr 2001
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posted 03-20-2003 01:25 PM
Both Steve and Rob,run way faster then I do.
Maybe if I took off my air filter I'd run faster too.I'll try it this year at the track only.  ------------------
SCOOP
oddly obsessed with big scoops on little Mustangs 2.26 60'S
14.9 @ 90.86MPH 65 coupe,351w,C4,Big Boss 429 hood scoop,8"3.40 TracLoc,Cragar SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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Mpcoluv
Gearhead Posts: 1333
From: Charlotte NC usa
Registered: Apr 2001
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posted 03-20-2003 02:40 PM
Winston Cup cars run a 16" x 4" filter I think.
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67Coupster
Gearhead Posts: 188
From: Fortson, GA, USA
Registered: Oct 2001
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posted 03-20-2003 03:21 PM
I run a 14 by 3 K&N in mine and run 6.90 in the 1/8 which should be somewhere around 10.90. I had to put one on mine because with the Boss 429 hood scoop the airflow across the carb was distrupting the carb signal causing the car to lay down progressively worse with each gear change. Wow I said that all in one sentence . Later ------------------
James
67 Coupe
393W, 4 Speed,
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Ryan Wilke
Gearhead Posts: 2289
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 03-20-2003 04:33 PM
Dan,
The K&N boys have a good explanation on how to calculate the size you should use at their site. Go here:http://www.knfilters.com/facts.htm#SELECT As Mpcoluv indicated, Winston Cup cars use them and you know Sand draggers and most mud racers use them, so it can be done and still make goobs of power....but as you can guess, it's very easy to install one that will chock off your engine/carb because it is too small!!! Good Luck!
Ryan
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 03-20-2003 06:04 PM
I asked the question because I tried removing my 12x9 oval K&N filter and put a 4" velocity stack on in it's place and I immediatly noticed that the motor felt a little lean. Wouldn't that mean that the filter could be causing a restriction?DanH
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 03-20-2003 06:48 PM
What about you Alex?? How do you feed your air into that monster?DanH
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Hans olsson
Gearhead Posts: 718
From: Sweden
Registered: Apr 2000
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posted 03-21-2003 08:56 AM
A 14*3 inch filter lowered the Avg 5 Hp on a dyno session. We have yet to try the filter on a actual run.
------------------
- 71 Mach1 351c
- E/SA 11.89-110 mph
- F/SA 11.76-111 mph
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 03-21-2003 10:27 AM
I could live with a 5 HP loss to protect the motor I guess. I'm curious to see what difference it would make if you run the filter. Our cars are very close in MPH.Thanks ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank and girdle, 5.4 H-beams, Forged slugs, TFS alum. heads, ported Stealth 8020 intake, Xtreme 274 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
1st pass: 12.50 @ 112 mph
DanH
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SteveLaRiviere
Administrator Posts: 44935
From: Saco, Maine
Registered: May 99
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posted 03-21-2003 10:41 AM
No filter = honing your engine while you drive  ------------------
'70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150 Please remember our sponsors,
Mustangs Plus, NPD, Osborn Reproductions, MyFordPerformance.com, and FordRamAir.com
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Hans olsson
Gearhead Posts: 718
From: Sweden
Registered: Apr 2000
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posted 03-21-2003 10:47 AM
quote:
Originally posted by SteveLaRiviere:
No filter = honing your engine while you drive
Is that a bad thing.
------------------
- 71 Mach1 351c
- E/SA 11.89-110 mph
- F/SA 11.76-111 mph
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SteveLaRiviere
Administrator Posts: 44935
From: Saco, Maine
Registered: May 99
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posted 03-21-2003 10:54 AM
It's great for killing 'skeeters! ------------------
'70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150 Please remember our sponsors,
Mustangs Plus, NPD, Osborn Reproductions, MyFordPerformance.com, and FordRamAir.com
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Ryan Wilke
Gearhead Posts: 2289
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 03-21-2003 12:05 PM
quote:
Originally posted by Hans olsson:
A 14*3 inch filter lowered the Avg 5 Hp on a dyno session. We have yet to try the filter on a actual run.
Hans,
I don't know the particulars on the engine or the design of filter/base/lid that you ran the dyno test on, but - I'd guess that if you plugged in the engine specs into the formula provided by K&N, what you used may not of matched what K&N would of recommended. I'd guess if you used a 14" X 6" filter and a K&N base/lid, you may not of noticed the dyno loss. If you choose to believe what K&N says on their site, the type of filter material, the square inches of actual filter material, the type/design of filter lid & base, the peak rpm, the engine cid, etc. all are factors in determining which size filter to use...... Bottomline IMO:
- Most racers run without a filter; because most racers have a concern with hood or hood scoop clearances; thus they choose to run without a filter because they don't want to deal with the recommended filter dimensions.
Ryan ------------------
The '3-Pedal Attitude' Kid
In a '69 FB w/ 4-spd'd 306",
but the 460+ is on the stand!
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Ryan Wilke
Gearhead Posts: 2289
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 03-21-2003 12:37 PM
quote:
Originally posted by SteveLaRiviere:
It's great for killing 'skeeters!
....which is a good thing.... 'cause with the snow leaving us in a hurry, those West Nile Carriers will be upon us  before we know it! -- Another thought on the filter sizing issue; Recall those dinky 6" X 2" paper filters that we see on show cars, how many cfms do you think they provide the carb? -- They probably only allow 350cfms into a 750 carb....... which is OK as long as they never turn the engine over 3K rpms! Ryan
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steve'66
Gearhead Posts: 9489
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 03-21-2003 12:38 PM
quote:
Originally posted by Ryan Wilke:
Bottomline IMO:
- Most racers run without a filter; because most racers have a concern with hood or hood scoop clearances; thus they choose to run without a filter because they don't want to deal with the recommended filter dimensions.
Ryan
That's why I don't run one. A filter that would fit between the 408w and the shelby hood is very restrictive.  SteveW
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 03-22-2003 03:54 AM
SteveW, do you use your scoop as a cold air intake or is it just for show?
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Fastymz
Moderator Posts: 20708
From: Reno Nv USA M&M#1240
Registered: Apr 2001
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posted 03-22-2003 01:06 PM
Steve has a real mans scoop. ------------------
SCOOP
oddly obsessed with big scoops on little Mustangs 2.26 60'S
14.9 @ 90.86MPH 65 coupe,351w,C4,Big Boss 429 hood scoop,8"3.40 TracLoc,Cragar SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
[This message has been edited by Fastymz (edited 03-22-2003).]
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