Foam Filter Efficiency
Apr 23, 2005, 09:36 PM
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Foam Filter Efficiency
Many people suggest the HKS RS as one of the best intakes out there. However I am rather worried about the filtering efficiency of the foam filter. It just seems incredibly porous compared to your average K&N style filter. Am I being too ****, or what?
Apr 23, 2005, 10:36 PM
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Foam is actually the best filter you can get. It is whats used in everything from F1 to WRC. Now, I'm not sure about the HKS RS, but it is designed for the street, so I would assume it should be fine.
Apr 24, 2005, 08:36 AM
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I have had my intake for a year and a half now. I have changed it twice (every 5k)
It catches alot of crap, but i did notice a small layer of dust stuck to the inside of the intake tube. I worried about it for all of 3 seconds.
I have alot of buddies that run their summer cars with NO filter at all. They figure all that piping from turbo to intake manifold is gonna be long enough for debris anyway.
I have not had any probs. The filter does its job well enough for me.
It catches alot of crap, but i did notice a small layer of dust stuck to the inside of the intake tube. I worried about it for all of 3 seconds.
I have alot of buddies that run their summer cars with NO filter at all. They figure all that piping from turbo to intake manifold is gonna be long enough for debris anyway.
I have not had any probs. The filter does its job well enough for me.
Apr 24, 2005, 04:01 PM
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I think both K&N and foam filter well enough, but the foam needs to be replaced more often. I'm worried more about all the oil that's in my intake track than dirt and debris.
Apr 24, 2005, 05:43 PM
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The problem with the HKS filters in general is twofold. First, the filter is foam, and it doesn't stop all of the smaller debri, at least not on the HKS Superpowerflows. Two, the HKS filters I've seen and run were small in surface area and restrictive, no doubt about it.
To prevent a powerloss on the top end which would be noticeable, you should have 1 in2 of filter surface area for every 6 cfm of airflow, according to K&N's recommendations. My HKS powerflow had 75 in2 surface area, good for about 450 cfm. My current K&N has 165 in2 surface area, good for about 990 cfm. That K&N still had a pressure drop of about .9 psi from 5000-7000 rpm, when flowing about 35 lb/min. So I'd grab the biggest K&N or cotton gauze airfilter I could get my hands on and skip any HKS filter at all costs.
To prevent a powerloss on the top end which would be noticeable, you should have 1 in2 of filter surface area for every 6 cfm of airflow, according to K&N's recommendations. My HKS powerflow had 75 in2 surface area, good for about 450 cfm. My current K&N has 165 in2 surface area, good for about 990 cfm. That K&N still had a pressure drop of about .9 psi from 5000-7000 rpm, when flowing about 35 lb/min. So I'd grab the biggest K&N or cotton gauze airfilter I could get my hands on and skip any HKS filter at all costs.
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Apr 24, 2005, 06:39 PM
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I read one of Al's posts awhile back where he had a customer dyno with an HKS RS intake, then shortly after with a K&N drop-in in the stock airbox, he ended up losing 10whp with the drop-in up top.
He stated that it didn't filter as well as cotton type filters out there, and said that based on my location (FL), that I should stick to a drop in.
He stated that it didn't filter as well as cotton type filters out there, and said that based on my location (FL), that I should stick to a drop in.
Apr 24, 2005, 07:10 PM
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The drop in K&N airfilter is only 45 in^2, plus you have the restriction of the entire airbox assembly. I swapped out my large K&N cone for the stock airbox/K&N panel drop in filter, I lost 4 psi of boost and a huge amount of power.
You don't want a drop in, that is almost no better than stock. A bigger airfilter actually filters BETTER, compared to the same type of element, because the mass flowrate per square inch is less. It will load up with dirt at a much slower rate. Its a win/win situation going huge on an airfilter. K&N's let thru dust, but HKS filters let thru little pebble sized debri. On top of that, HKS is for certain charging a fortune for that filter setup. K&N kits are cheaper than dirt, their included airfilters are fairly large, and the quality matches anything HKS puts out.
You don't want a drop in, that is almost no better than stock. A bigger airfilter actually filters BETTER, compared to the same type of element, because the mass flowrate per square inch is less. It will load up with dirt at a much slower rate. Its a win/win situation going huge on an airfilter. K&N's let thru dust, but HKS filters let thru little pebble sized debri. On top of that, HKS is for certain charging a fortune for that filter setup. K&N kits are cheaper than dirt, their included airfilters are fairly large, and the quality matches anything HKS puts out.
