you won't need to adjust the a/f ratio if you use the Ralliart Cotton Mesh Filter. I have one, its not foam.

 

I take that back, I was referring to the foam one.

In other words, I think foam filters tend to screw with your readings the most.

 

You can get the A'pexi intake from many vendors. I personally picked mine up from Francis @ A-Spec. He had an overstock deal running on them a while back.

Do a search, there is another thread with a link to a test that shows the apexi filter does the best job of filtering and gives the most hp.

Almost forgot - the Apexi filter is a dry type (no oil) and is washable.

 

I found this:

>Ok, my curiosity is piqued, John. I thought that K&N's were supposed
>to be the trick thing to use for air filtering? Also, do you have any
>good ideas about routing a duct to the windshield cowling? Would it
>make that big a difference in terms of hp? (or any at all?)

K&N is simply the company that spends the most ad dollars and therefore
gets the most attention. I learned my very expensive K&N lession
over 20 years ago when I was actively building racing engines. K&N
had some contingency money available so I replaced our Filtron
(Oiled foam) filters on our motocross bikes with K&N. An engine that
would normally last 10-15 heats was completely trashed by dirt
before the first one was over. Frankly I've never seen such massive
filter failure. Figuring it was a fluke, I tried it again at
another race. Same result. Massive wear, grit all over the
intake track - trashed engine. Lesson learned. The K&N that
came on a used Z I bought awhile back is exactly the same
construction as the 20 year old filter still somewhere in my junk
collection.

K&N follows a familiar path. Lots of hype, lots of advertising
dollars which effectively buys them good press, and an excellent
no-questions-asked warranty. A warranty that pays people off
to keep 'em quiet. One can get away with a lot on the street
simply because there isn't much dirt under normal conditions.
But off-road is another matter. There is an easy test of a
filter that you can do. Simply thoroughly clean the air cleaner
housing and the carb intake. Then coat it with a very thin coating
of light grease. A portion of any dirt that gets through the filter
will be trapped in the grease. Run it awhile and then feel the grease.
If it is gritty, the filter isn't working. It will be gritty with
a K&N.

There is simply no better filtration media than paper. The very best
filters, HEPA filters, used to catch sub-micron particles in nuclear
plants and hard disk drives, is simply a very refined paper. If the
paper element doesn't flow enough air, install a larger one. The only
time I won't use a paper element is when there is a possibility that
the filter element can become wet. Then I'll use oiled foam. For
REALLY dusty environments such as dirt tracks and off-road racing,
I'll do like every other mechanic and use a foam prefilter over
a paper element.

As far as picking up air under the cowl, you can simply go through the
firewall above the partition that separates the cowl space from
the interior. I've done that with stock carb setups. Depending on how
far the horns of the webers stick out, this may or may not be easy.

 

And this:

I would stay with the OEM filter. The proof that you say you might need is something you need to "prove" to yourself. Do a UOA for each of 10k OCI's. K/N, OEM filter and NO filter. (Silicon) is a HUGE tell.Compare and contrast the three.

There are only a few factors at work here. And this is where the air intake/oiled media air filter marketeers do their finest work.

Most if not all air intake and (filter systems being a part) are specified to pass a "snow prophalactic" test. The practical sentence would be; i.e, after hitting a snow drift of 3 feet.... yada yada. Otherwise one runs the risk of snow/water ingestion and a % of hydrolocked engines is not a good gig. So the air intake system is designed to be somewhat of a maze to snow, and somewhat less to its sister condition- water. This maze can be seen in some if not most cases as "restrictive" SO... simple removal will make it LESS RESTRICTIVE!!??

So if one determines the snow prophalactic is unneeded with the attending exposures to snow and water and greater exposure to chance of warranty denial IF you happen to hydrolock the engine then....

If you do a dyno before and after removal, you will find viola- "FOUND" HP !!! Of course a certain amount of gain and or loss can be attributed to measurement error.

Another issue and the fine print on oil media air filters will warn you against; will be oiling too much. Even if you oil it just right you increase the chance of mineral oil migrating to the critical MAF components that have been known to fail after being coated with mineral oil.

So to me:

1. oil filter media does not filter as well as oem paper/synthetic

2. oil can migrate to intake and critical MAF components increasing the chance of failure due to oil migration

3. oil and oil cleaner media costs too much

4. the filter media costs WAY more than OEM filters

5. you have to clean the cotton/foam media and re apply the mineral oil. If a shop were to do this, they probably would charge you 1/2 hour of shop time say at the going rate of 95 per hour. It is of course an unspoken given that one does this themselves.

 

I picked up 1mph at the track with switching from my stock to my hks. I made two passes with the stock one and the rest with the hks and all runs were 1-2mph higher. So Im happy with mine. No tuning needed.

 

More air filter info:

http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm

 

thanks zmili

ichiban can you give me any web site for the a'pexi filter

i tryed a-spec.com didn't work

 

zmeli what do you think is the best drop in filter besides the ome filter?

what about a'pexi & whats a hepa filter? thanks for your info

 

Works air filter is great. Its been a year in development and is specifically designed for the USDM Evo. You can't go wrong with it.

 

how often do you change the stock air filter? i have 10,000 miles on mine i think i need to change it right

i would go with hks but you have to change it every 5000K i hope thats not the same for the stock one

 

http://www.dirtcheapracing.com/tech/airfilter/

I am looking for a Filter made is Aus that is made for motorsports/ off-road use. I can't find the link. I will keep trying.

 

I got one too. 25 shipped.

 

Air Filters using dry media (paper) help reduce the risk of poor engine performance.

In vehicles where air-fuel mixture is controlled by an airflow sensor wire, an electric current passes through this wire giving a measurement of electrical resistance, proportional to air flow.

However false readings in this sensor can occur when oil, dust and contaminants from oil wetted filter media build up on the airflow sensor’s hot wire.

This may affect the engine’s performance by providing inaccurate data, leading to the engine management system altering the air-fuel mix.

 

what's Ryco A1412 where can i get one?