Looking to replace my old foam filter from my Alta CAI with a K&N filter. Any recos on a style? I have found three different ones on their website that fit and wonder if one style has better air flow characteristics. RX-4870 - K&N Universal Air Filters, Universal X-Stream Clamp-On direct from K&N RU-4870 - K&N Universal Air Filters, Universal Rubber Filter direct from K&N RR-2801 - K&N Universal Air Filters, Reverse Conical Universal Air Filter direct from K&N
You want the one with the most filter area. That would allow the most air to pass through to the intake at any given moment. The Madness CAI that I have is similar to the Reverse Conical version (RR-2801). The caveat being, the Reverse Conical is the most difficult to clean and oil when the time comes for that.
I haven't done the math but if you're going for the greatest overall filter surface area I'm not sure the one with the inverted top is actually the winner or, if it is, by how much. You can't tell from the pics how big that small interior cone is plus if I'm reading the numbers right the outer cone is significantly shorter than the others. I assume the inverted top model is lighter because of the aluminum top, shorter length and it's short flange length but it also requires significantly less oil for filter re-oiling. Seems like that would be directly related to filter area... RR-2801: 0.68 oz (20 ml) RU-4870: 1.24 oz (37 ml) RX-4870: 1.16 oz (34 ml)
Foam filters, especially the double layer ones are more restrictive then the paper or cotton ones. If you get an intake like a DDM and use the UNI foam filter you are blocking all the air you have just opened it up for. JCW = K&N Dinan= K&N K&N FTW
Cotton filters work good when clean, but they get dirty faster and won't flow nearly as well when clean. The foam filters are way more consistent than the foam filters are over the service life. Why do you think all of the off road racers and bikers use foam?
I clean my filter and I don't dip it in oil like others because I have a dry cotton filter. I don't drive off road in the dirt, or live in a very high dust quarry and my Mini is not a bike. I will use a foam filter in my Mini if I ever decide to run the Baja 1000 in my car though.:ihih::lol: Check these filters out...Made in the USA. http://www.defendersofspeed.com/dry-no-oil-filter-for-dos-r56-thru-r59-cai/
Filter I replaced the oil cotton (K&N or Mini-Madness) with a similar one (but dry - no oil) from Amsoil. It also has the inverse cone in front for greater area. The filter is made with their nano-fiber - same stuff used on tanks in the gulf wars (I'm told). Dirt particles are bigger than spaces between filter fibers, and supposedly stays on the outside of the fibers so it breathes when dirty. Amsoil also has a polyester-type sock for over the filter for more protection. Anyway, I couldn't tell whether the car had any less power vs. the cotton (oiled filter) which was getting black and dirty. At least now I know I'm getting a good combination of good filtration and air flow. 06 R52, Madness Performance package II, plus all the bars and braces, FSD shocks, DOS copper IC, AlTA inlet tube, Polyurethane engine bushings.
Sorry man but I am not a fan of foam filters. I had one for years with my DDM and hated it. Happy motoring :devil: