Aif filter restriction

[Vader]

This past winter I decided to change the air cleaner on my FE to one of those "Cobra" Oval style. They are readily available from Tony Branda, Finish Line, etc.among others. When I was installing it I noticed that it was a lower profile than the Wysco air cleaner that it was replacing. I did some quick measurements of the surface area of the element and since it was about 15% larger I decided that it probably would have, if anything, a small effect. Boy was I wrong. I put my car on the dyno this week and it had lost 33 hp. Most noticible above 4k with lots of black smoke
My engine tuner/dyno operator said he had seen the same symptons a couple of weekes earlier with an SPF that was running a 428 with the same air cleaner. We did some more pulls, with the orignal Wysco, the "Cobra" Oval, and no air cleaner. No doubt, it was the restriction from the filter.
The original Wysco is a 15 x 8 inch oval and has a 2 inch high K & N filter. The Cobra style is a much larger size- 20 x 9 but comes with a 1 3/4 inch high paper filter. I'm going to replace the element with a K & N style that's 2.5 inches tall and will re-test.

[scootter]

I was also surprised. On the SCOF site there is an air cleaner calculator. I think with the paper oval I lost 40 or so HP. With the K&N filter it was about 15hp or so.
Scott

[lineslinger]

Is this the KN filter you are talking of? Still trying to figure out whether or not extra hood/scoop clearence is going to be needed.

[Vader]

Yes, it's the same air cleaner, but it looks like you have a taller element. I believe that the bigger issue is the material. I don't think that the paper will flow as well as the K & N type. So long as you can get enough of a surface area for the size of your CFM requirements, you're fine. In my case, we had already tuned the carb with the K & N in place, then I changed the mix by putting on a more restrictive filter. It really wasn't that noticible around town since I'm pretty conservative on those evening drives. If you wind it up though, it is certainly something you notice- lots of black exhaust. I went to the Branda catalog and they offer 2 K & N style filters options for this style of air cleaner. One is the same height, and the other is 1/2 inch taller. The taller one will be a tight fit under my hood. I'm going to mock one up before I order the replacement. I've decided that you probably can't have too large a filter.

[rblong]

Mine is the same as Lineslinger, and a recent dyno session revealed only 5 HP loss over no filter at all. I thought that was pretty good.

[Vader]

Rblong:
We found the same loss as you did, 4hp loss with the wysco w/the K & N vs. no filter.

[Burnd]

Originally Posted by scootter

I was also surprised. On the SCOF site there is an air cleaner calculator. I think with the paper oval I lost 40 or so HP. With the K&N filter it was about 15hp or so.
Scott

SCOF site please??? I don't know the acronym. I'm perfomance experimenting with filters right now. Thanks.

Bernie

[427SnakeSC]

http://www.secondstrike.com/Technica...leanerCalc.asp Quick formula for getting cfm on round air cleaners Diameter X Height X 3.12 X 6

[DavidNJ]

Has anyone tried a K&N Dropped Control Flow? It is only 2.12" above the carb flange with a 3.5" high, 16" diameter filter. The shield blocks hot air from the radiator.

[JBCOBRA]

Hi Vader!
If you get the filter Linslinger has a picture of, that air filter should work well as long as you don't have a chokehorn. Does your carb have one or not? If it does, get it milled off. Makes a big difference