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How much airflow will a 5.0 mustang dual snorkel air cleaner support? or rather, how much HP? I'm actually thinking of taking my OEM air cleaner for my Cougar, and putting on another snorkel. Waste of time vs a full open unit with a K&N filter lid? I'd duct air into it from under the bumpers with dryer duct.
 

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Air Cleaner size

It depends on the size of the motor, (CU IN), RPM's (air pump), and if there are any flow restrictions. I ran a K&N filter that was 14" diameter and 3" tall on a 521 cu in motor turning 6500 RPM and it was not big enough. I added the K&N flow thru top and the problem was solved. Just my two cents.
 

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Flow restriction.

I restrictor-plated a bunch of american iron series road race cars to meet dyno-checked power limits (rules). What I found was 53mm = 300rwhp...always within 5mm of this number, regardless of engine.

So if you have 2x that surface area, that's 600rwhp...and if memory serves, you have more than that.
 

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Air filter size.

I found this on K&N's website. I don't know about 53 mm/300 HP but I can ciffer what K&N is saying whether it's correct or not, I don't know but it worked for me. And I didn't know about this formula at the time. I was stuck with what I could run due to hood clearance.

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= (CID X RPM) / 20,839

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.

A = (350 X 5500)/20839= 92.4 square inches

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.

H = A/(DX3.14) + .75

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

Example:

H= 92.4/(12X3.14) + .75= 3.2 inches


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.

Using their formulas for my combintion you get.

A= (521 X 6500) / 20839 = 162.5

H= 162.5/ (14X3.14) + .75 = 4.45 inches tall required

So maybe they know what they are talking about also, because I picked up when I added the open flow top to my 14" X 3" air filter. Just trying to help.
 

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For BBF with Dom. Carb.

I will post in the context of a large engine with 4500 series carb. because of the special challenges involved with getting sufficient volume of filtered air to these motors - especially if hood clearance is an issue, as it is with high port heads like C-460s - and the relative lack of air cleaner support for the 4500.

I believe there are basically four choices:
1) A tall filter, which can be 14" or less diameter, since it is tall -- this assumes a truck or something that does not have much in the way of vilibility constraints;
2) A Wix 16"x4" filter like are sold by http://www.bsrproducts.com/
3) The K&N Mopar-style semi-rectangular filter that is 3" tall but has more circumference than a 16" filter and is the only high flow filter I know of that is less than 4" tall; or
4) What I call a snorkel system using an air box that encloses a high volume cone filter. K&N, and probably others, offers cone filters that will flow large numbers on the order of 1400 CFM, but the high flow cone filters are lengthy and require a box/housing that holds up both ends.

I use choice 4) now because I felt the snorkel provided a more effective turn into the carb and enabled a smaller diameter vision obstruction than the Mopar style or the 16x4. The design of this system is pretty clearly described on the "Underpinnings" page of my site.

If the Mopar-style deal is used a filter housing will probably need to be constructred. I ran this combo. for a couple years before changing to a snorkel,

Both BSR and http://www.ramairbox.com/ offer parts required for a 16x4 setup. I think these guys make an ideal carb hat for a snorkel system: http://www.superiorairflow.com/
 
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