Aftermarket air filter necessary?
09-22-2009, 05:03 PM
#1
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Aftermarket air filter better than OEM?
Disclaimer: I don't claim to know jack **** about air filter tests or its results. I came to my own conclusion based on what I read on my own on the interwebz from information I believe to be credible and unbiased.
Okay there are a ton of useless air filter and intake threads already so I figure one more couldn't hurt. Some of you may know already but my opinion on aftermarket intakes for the RX8 are for the most part, a waste of money. If if its worth it to you that fine this is just my opinion. the factory induction system is pretty damn efficient and with the air box mod, RB duct, and a K&N filter I think its as perfect as it gets.
But, after doing some research (not RX8 specific) I have found that factory air filters are not really a restriction on factory power level cars. I have also found that some OEM replacement filters flow pretty damn good and filter well. Basically the differences in flow really don't equate to real world HP. But there is little argument that the aftermarket filters that flow well, definitely do not filter well.
So then I asked myself, do I care more about the sound and the extra 1-2HP that I am getting from my K&N or do I care more about filtering out all the junk that is going unfiltered into my engine? Well I would like your thoughts on the matter but i think I'm done with my K&N drop in.
http://www.bobistheoilguy.com/airfilter/airtest3.htm
Okay there are a ton of useless air filter and intake threads already so I figure one more couldn't hurt. Some of you may know already but my opinion on aftermarket intakes for the RX8 are for the most part, a waste of money. If if its worth it to you that fine this is just my opinion. the factory induction system is pretty damn efficient and with the air box mod, RB duct, and a K&N filter I think its as perfect as it gets.
But, after doing some research (not RX8 specific) I have found that factory air filters are not really a restriction on factory power level cars. I have also found that some OEM replacement filters flow pretty damn good and filter well. Basically the differences in flow really don't equate to real world HP. But there is little argument that the aftermarket filters that flow well, definitely do not filter well.
So then I asked myself, do I care more about the sound and the extra 1-2HP that I am getting from my K&N or do I care more about filtering out all the junk that is going unfiltered into my engine? Well I would like your thoughts on the matter but i think I'm done with my K&N drop in.
http://www.bobistheoilguy.com/airfilter/airtest3.htm
Last edited by 9krpmrx8; 09-23-2009 at 09:26 AM.
09-22-2009, 06:23 PM
#2
Registered
i have used the K&N because i am cheap. i clean more often but just to make sure. There are those who disagree that K&N doesn't work as well. i also make my own incabin filter. same reason i change my own oil and filter.
09-22-2009, 08:04 PM
#3
K&N's biggest advantage is ... well, re-usable almost forever.
Disadvantage is ... it does NOT filter as well as some other "disposable" filters.
I mean its not so bad, but if u want "best of the best" filtration. You might want to look for something else.
If 1 is best filtration and 5 is the worst. K&N is somewhere between 2.5 to 3.
Free flowing vs Filtration .... you can only pick 1 I guess.
Disadvantage is ... it does NOT filter as well as some other "disposable" filters.
I mean its not so bad, but if u want "best of the best" filtration. You might want to look for something else.
If 1 is best filtration and 5 is the worst. K&N is somewhere between 2.5 to 3.
Free flowing vs Filtration .... you can only pick 1 I guess.
Last edited by nycgps; 09-22-2009 at 08:16 PM.
09-22-2009, 10:48 PM
#4
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Exactly. I do everything myself as well and I have used K&N's for years on every car I have owned. I'm just wondering if all that extra crap getting in to just get more flow is worth it. I was surprised to find that on a stock car the flow characteristics are not that different (I guess each car would differ).
09-22-2009, 10:50 PM
#5
Administrator
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Necessary? Is it necessary for me to drink my own urine?
No, but I do it anyway because it's sterile and I like the taste.
No, but I do it anyway because it's sterile and I like the taste.
09-22-2009, 11:00 PM
#7
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bonus points if you know what that quote is from.
09-22-2009, 11:22 PM
#9
Super Moderator
Yeah, I have heard the OEM filter does a pretty good job...what it is meant to do...I guess that is to filter the Air..
09-22-2009, 11:42 PM
#10
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I guess I just never thought of it for some reason but now I am in preventive maintenance mode to protect this engine and I'm pumping clean premix into my combustion chamber so why would I pump dirty air in it.
09-23-2009, 01:12 AM
#11
Super Moderator
Yep good idea...its not so much dirty air (which is not good), but a dirty air filter restricts air flow, over time less and less air is there for engine to function, so poor RENNY chokes to death!!
09-23-2009, 07:47 AM
#12
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I wonder which OEM filters the best? Must research.
http://www.bobistheoilguy.com/airfilter/airtest3.htm
http://www.bobistheoilguy.com/airfilter/airtest3.htm
Last edited by 9krpmrx8; 09-23-2009 at 09:26 AM.
09-23-2009, 11:46 AM
#13
Lubricious
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Hold your K&N filter up to the sun. You may be surprised at the size of some of those "pores"!
I used a K&N on my Miata, partially because of the horsepower claims, and partly because of the "re-usable forever" aspect. I came to realize that a couple of HP is not noticeable, and the process of washing, drying, and re-oiling a K&N filter is a pain in the ***. Also, on the RX-8 there's the issue of the MAF sensor getting oiled and gunked up, which can easily take away a lot more performance than the filter can ever hope to give you. It's a lose-lose situation, imho.
That being said, my Miata ran fine for over 150,000 miles before I sold it, so even if the filtration efficiency was reduced, it certainly didn't make a dime's worth of difference to me. It's unlikely that you'd get near 150,000 miles on a Renesis before needing a rebuild, so maybe it doesn't matter. The K&N filter is prettier.
My favorite air filter of all time was the oil-bath air filter on my 1967 Beetle. Big canister of (horse hair? Coconut hair?) submerged in oil. You'd just service the filter along with your oil change. Lasted forever and some say was better filtration than paper filters.
I used a K&N on my Miata, partially because of the horsepower claims, and partly because of the "re-usable forever" aspect. I came to realize that a couple of HP is not noticeable, and the process of washing, drying, and re-oiling a K&N filter is a pain in the ***. Also, on the RX-8 there's the issue of the MAF sensor getting oiled and gunked up, which can easily take away a lot more performance than the filter can ever hope to give you. It's a lose-lose situation, imho.
That being said, my Miata ran fine for over 150,000 miles before I sold it, so even if the filtration efficiency was reduced, it certainly didn't make a dime's worth of difference to me. It's unlikely that you'd get near 150,000 miles on a Renesis before needing a rebuild, so maybe it doesn't matter. The K&N filter is prettier.
My favorite air filter of all time was the oil-bath air filter on my 1967 Beetle. Big canister of (horse hair? Coconut hair?) submerged in oil. You'd just service the filter along with your oil change. Lasted forever and some say was better filtration than paper filters.
09-23-2009, 01:09 PM
#14
The answer to your question is........... where do you live?
Hot and dusty... keep it stock.
One way to check is to open up any air box where you live and see how many stones and leaves are in there.
If you get too many leaves, and sand in there then keep it stock.
Hot and dusty... keep it stock.
One way to check is to open up any air box where you live and see how many stones and leaves are in there.
If you get too many leaves, and sand in there then keep it stock.
09-23-2009, 01:33 PM
#16
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I love my Racing Beat intake which has a K&N filter in there. As people have mentioned, you have to be careful when re-oiling the filter. Less is more. 
09-23-2009, 01:47 PM
#17
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Yeah. Texas is definitely Hot and Dusty. The bottom of my battery box is always full of sand and stuff. I have always used K&N filters on my previous cars without issue but then again the Renny is a unique beast and need all the help it can get to survive in Texas.
Last edited by 9krpmrx8; 09-23-2009 at 02:13 PM.
09-23-2009, 03:51 PM
#18
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Mazda
09-23-2009, 03:59 PM
#19
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K&N is better than others! http://www.mkiv.com/techarticles/filters_test/2/
Are you in the SCCA and get Sports Car mag? ULLOSE's car did a filter shootout last year. I don't remember the exact results but the diff between a dirty and new K&N was huge. Dirty K&N was as good as a stock filter. New K&N and a new Green filter were good for 6hp or so.
Are you in the SCCA and get Sports Car mag? ULLOSE's car did a filter shootout last year. I don't remember the exact results but the diff between a dirty and new K&N was huge. Dirty K&N was as good as a stock filter. New K&N and a new Green filter were good for 6hp or so.
09-23-2009, 04:05 PM
#20
K&N is better than others! http://www.mkiv.com/techarticles/filters_test/2/
Are you in the SCCA and get Sports Car mag? ULLOSE's car did a filter shootout last year. I don't remember the exact results but the diff between a dirty and new K&N was huge. Dirty K&N was as good as a stock filter. New K&N and a new Green filter were good for 6hp or so.
Are you in the SCCA and get Sports Car mag? ULLOSE's car did a filter shootout last year. I don't remember the exact results but the diff between a dirty and new K&N was huge. Dirty K&N was as good as a stock filter. New K&N and a new Green filter were good for 6hp or so.
So then I asked myself, do I care more about the sound and the extra 1-2HP that I am getting from my K&N or do I care more about filtering out all the junk that is going unfiltered into my engine? Well I would like your thoughts on the matter but i think I'm done with my K&N drop in.
http://www.bobistheoilguy.com/airfilter/airtest3.htm
http://www.bobistheoilguy.com/airfilter/airtest3.htm
09-23-2009, 04:12 PM
#22
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Best at what? I know the K&N makes more power but at what cost is my issue? The thought of dirt being inducted into my engine makes me cringe when I think of all I do to assure the engine gets clean (as possible) liquids.
Paging ULLOSE for input!!!
Paging ULLOSE for input!!!
09-23-2009, 04:28 PM
#25