[smittyseng]

Originally Posted by lust4speed

Except K&N has taken the folds into account with their stated flow rating of 6CFM per square inch of (exterior) filter medium.

Using the 6CFM figure, my 121 square inch sized round filter would flow 783CFM -- which wouldn't be enough to satisfy the needed 829CFM requirement of the 462 at 6,200 RPM. Since we proved on the dyno that the filter size was sufficient up to 6,500 RPM, I'd say that their estimate is somewhat conservative. That nice even 6CFM number was probably rounded down. I'd say that it would be entirely safe to use the 6CFM figure for figuring minimum filter size.

I avoided splitting hairs and simply installed a 5x14 K&N filter on the drag car. Probably didn't need it, but had the room so why not?

Remember though too, if a air filter will flow 783 cfm at a given vacuum like 1.5" or so (haven't found a EXACT number anyone will admit to) that it CAN and WILL flow more BUT it will create a vacuum inside the air cleaner affecting the tune of the carb AND it will reach a point where it goes from being a slight restriction to a terrible resriction, Smitty

[smittyseng]

Originally Posted by Engo

I dont think the math is correct since you did not account for the fact that the filter is folded. The filter area is much bigger.

You have a valid point, I haven't found if they are saying 6 cfm per sq inch of EFFECTIVE area or just area. If you cut the element out of the ends and stretched it out TIGHT I imagine the effective area would grow. In the case of this little 3X9 element though it still wouldn't grow ENOUGH, Smitty

[Steve C.]

According to K&N a larger diameter, short filter will flow more air than a small diameter, tall filter.

K&N formula to determine filter size located here .....
http://www.knfilters.com/filter_facts.htm


Out of interest I have talked with a tech rep at K&N about the air flow requirements for my 505cid engine and if the 'small' 9-inch dia K&N filter assy with X-Stream filter lid that I'm using is adequate. According to their formula a 505 cubic inch engine at 6000 rpm requires about 745 cfm of air flow. According to him the 9-inch assy with the X-Stream lid I'm using will support about 650 cfm. So he said on the street I'm fine. If I went to the track I'd just remove it.

He also supported comments made that the entrance on a Holley 'HP' series carb with it's smooth contour does in fact act like their Stub Stack and will help it work with the X-Stream lid. Whereas apparantly a carb design without a smooth contour (w/ choke tower) and like a Q-jet doesn't work well with a X-Stream lid according to some on these boards.

If interested, previous thread about K&N X-Stream filter lid test on dyno:
http://forums.maxperformanceinc.com/...light=X-stream


.

[hopper146]

I stopped and picked up an Edelbrock 14x3 on my way to the dyno for my IAII. Was suprised to find the out of the box cheap paper filter that came with the assembly only cost me 2hp. Only pulled to 6000rpm though.

[Engo]

Originally Posted by Steve C.

According to K&N a larger diameter, short filter will flow more air than a small diameter, tall filter.

K&N formula to determine filter size located here .....
http://www.knfilters.com/filter_facts.htm


Out of interest I have talked with a tech rep at K&N about the air flow requirements for my 505cid engine and if the 'small' 9-inch dia K&N filter assy with X-Stream filter lid that I'm using is adequate. According to their formula a 505 cubic inch engine at 6000 rpm requires about 745 cfm of air flow. According to him the 9-inch assy with the X-Stream lid I'm using will support about 650 cfm. So he said on the street I'm fine. If I went to the track I'd just remove it.

He also supported comments made that the entrance on a Holley 'HP' series carb with it's smooth contour does in fact act like their Stub Stack and will help it work with the X-Stream lid. Whereas apparantly a carb design without a smooth contour (w/ choke tower) and like a Q-jet doesn't work well with a X-Stream lid according to some on these boards.

If interested, previous thread about K&N X-Stream filter lid test on dyno:
http://forums.maxperformanceinc.com/...light=X-stream
.

Since their formula doesnt account for different depth of the foldings in their filters I dont think its much value to it... my guess is KN just want to sell filters...

[smittyseng]

Originally Posted by Steve C.

According to K&N a larger diameter, short filter will flow more air than a small diameter, tall filter.

K&N formula to determine filter size located here .....
http://www.knfilters.com/filter_facts.htm


Out of interest I have talked with a tech rep at K&N about the air flow requirements for my 505cid engine and if the 'small' 9-inch dia K&N filter assy with X-Stream filter lid that I'm using is adequate. According to their formula a 505 cubic inch engine at 6000 rpm requires about 745 cfm of air flow. According to him the 9-inch assy with the X-Stream lid I'm using will support about 650 cfm. So he said on the street I'm fine. If I went to the track I'd just remove it.

He also supported comments made that the entrance on a Holley 'HP' series carb with it's smooth contour does in fact act like their Stub Stack and will help it work with the X-Stream lid. Whereas apparantly a carb design without a smooth contour (w/ choke tower) and like a Q-jet doesn't work well with a X-Stream lid according to some on these boards.

If interested, previous thread about K&N X-Stream filter lid test on dyno:
http://forums.maxperformanceinc.com/...light=X-stream


.

Have you ever raced your car without the filter?

[Steve C.]

Smittyseng- Yes. Over the years when my car has gone to the track it never had a air cleaner installed. But it has never been a dedicated race car and I don't think the few times it was raced without a air cleaner hurt anything. That and I have a hood clearance issue. As the car is set up currently in order to get the Victor intake under my hood with the small 9-inch air cleaner installed the intake carb flange was milled down 0.650". The shaker scoop is mounted to my fiberglass hood and the air cleaner is actually up inside the scoop. It's now a street car only, for the most part we only took it to the track to confirm it's a 10-second ride. And when we did we never bothered to put on a carb spacer. But if I were to race it I could pull the air cleaner assy off and add on a carb spacer to retain back some of the power loss from cutting down the intake. On the dyno it lost about 8-10 hp with the intake flange cut down. I can run a Performer RPM intake with the air cleaner installed but I'd give up over 40 hp !

http://www.popularhotrodding.com/fea.../photo_16.html




.

[ta man]

The joys of having a Trans Am..one of the few cars with a hole in the hood yet has limited clearance to run higher than stock intakes!I run a torker 2 with no spacer on mine...would really like to run a 1 inch spacer to pick up a bit of power yet keep a big enough filter so I don't lose power in the process.

[smittyseng]

Originally Posted by Steve C.

Smittyseng- Yes. Over the years when my car has gone to the track it never had a air cleaner installed. But it has never been a dedicated race car and I don't think the few times it was raced without a air cleaner hurt anything. That and I have a hood clearance issue. As the car is set up currently in order to get the Victor intake under my hood with the small 9-inch air cleaner installed the intake carb flange was milled down 0.650". The shaker scoop is mounted to my fiberglass hood and the air cleaner is actually up inside the scoop. It's now a street car only, for the most part we only took it to the track to confirm it's a 10-second ride. And when we did we never bothered to put on a carb spacer. But if I were to race it I could pull the air cleaner assy off and add on a carb spacer to retain back some of the power loss from cutting down the intake. On the dyno it lost about 8-10 hp with the intake flange cut down. I can run a Performer RPM intake with the air cleaner installed but I'd give up over 40 hp !

http://www.popularhotrodding.com/fea.../photo_16.html




.

I was curious if you saw a speed difference between having it on and taking it off at the track. My engine is smaller than yours (462) and went from making 575 hp or so to about 535-537 with the 3x9 at wot the day we tested all the different air cleaners. These were back to back test. The power loss started at about 4500 up and the afr's at wot dropped about 2 full points. The motor sounded choked off and also at wot the restriction was enough that the map sensor reading went from 99 kpa (which is about .8" of vaccuum) to80 kpa which is about 6" of vaccuum. I had previously ran this air cleaner on a strong 69 gto that ran into the high 11.60's so I was surprised but did expect to see some kind of drop.
I also built this motor to go in my 1974 TA Clone and one of the options I was thinking about was mounting the scoop to the hood and running a 3x9 (I have previously done this). I am running a Victor intake BUT I am using a Scorpion throttle body that is just over 1.5" thick so other than IAC clearence issues I plan on using a drop base from Pro-touringfbody with a 14x3 or 14X4 air cleaner. I bought a Larry navvarro deal from Butler and sent it back) but the flat air cleaner they give you with it would be more restrictive than the k/n we are talking about, Smitty

[smittyseng]

Dyno vid and pic
http://www.youtube.com/watch?v=S-hcDnrSzIU

[Larry Navarro]

Smitty.....did you try running the wfo assembly?
.......or did you see the flat panel filter and figured it would be restrictive.
I should mention the fact that there are plenty of my customers who use that particular assembly.......aluminum heads, roller cam.....strong 500+ HP engines.
Here's the one issue folks fail to address when running a shaker......the opening of the scoop.
How much air will be pulled through that opening?
There is twice the surface area of the flat panel filter than the square inch opening of the scoop.
what item in this chain would be the restriction in airflow?

Just a thought to consider.

[Pontirag]

I have no scientific data to prove anything one way or another but it jst does not make sense that adding more air filter would harm the performance.

I recognise that with improved air flow including the addition of an extream lid you would want to go back and re tune the engine


I have always included a stub stack as well.

too many credable engine buildes swear by them and I have not experienced any detrimental change in performance going from cheapo filter to K&N and or by adding an Xtream lid.

Hood clearance is another deal al together.

It has always been understood that you want as large a filter as possible.

[smittyseng]

Originally Posted by Larry Navarro

Smitty.....did you try running the wfo assembly?
.......or did you see the flat panel filter and figured it would be restrictive.
I should mention the fact that there are plenty of my customers who use that particular assembly.......aluminum heads, roller cam.....strong 500+ HP engines.
Here's the one issue folks fail to address when running a shaker......the opening of the scoop.
How much air will be pulled through that opening?
There is twice the surface area of the flat panel filter than the square inch opening of the scoop.
what item in this chain would be the restriction in airflow?

Just a thought to consider.

Larry, I searched the internet for a way to speak to you directly before buying the wfo and before I sent it back to Butler. I do not wish to disparage you or the product you have put so much work and pride in in any way. After looking at how little clearence there was between my stock aircleaner lid and the drop base on my 74 TA I felt it would be a restriction so I read about your replacement drop base with the cool looking aluminum center lid. After trying to find your website and being un-succesful I found that Butler had it in stock. I called there and spoke to someone who told me it DID use a 14x3 air cleaner vs my stock 12 1/2 by 2 5/8 or whatever it is, like the pictures I had previously seen. I went ahead and ordered it, when I got it I was surprised that for the earlier applications it did NOT use a 14X3 air cleaner but used a flat panel air cleaner that was approx 5x9 inches. I was VERY leary about trying to make 600 hp thru a air cleaner that size, especially since I came acrossed data showing k/n rated air flow of there air cleaners at 6 cfm per square inch. At 45 sq inches x 6 cfm I was looking at about 300 cfm capability, even IF it could flow twice that it would still come up short in my application, solid roller, kre 320 heads, Victor intake with 2000 cfm throttle body turning well past 6000 rpm's. At this time I tested the K/N 3x9 air cleaner that had almost DOUBLE the square inches of your flat panel element and saw almost a 40 hp drop on the dyno in back to back testing against a 14X4 air cleaner. I called Butler and inquired about the performance capabilitys of what I had purchased from them, the person I spoke to that time said for something in the 600 hp range there was really no way I could expect that size of that element to work and that as long as I hadn't used it at all I could send it back which is what I did. If I had a 350-400 hp street car I would definately use your product but I just felt my application was a little too much for what it was capable of.
As far as the sq inches of the opening on the scoop vs the sq inches of the flat panel filter, my understanding is a un-obstructed/un-restricted opening can flow between 100-145 cfm per sq inch depending on entry radius, about 10-15 times as much as a filter per sq inch so I don't see a correlation there, Smitty

[Dragncar]

I have run a K&N velocity stack with the tall 5" element on 550ish HP 472 for years.
Did not notice any difference at the track with the steel top or the filter top.