I bought a jdm legacy with a cosworth filter in it but haven't checked it.
I've just recently bought a replacement but haven't changed yet.
I'll report back with my findings.

 

I binned mine and went back to the standard OE Subaru item.

 

Can you elaborate on the niggles.

 

Two OE Genuine Subaru MAF's went pop. Running rough. I changed plugs and coil packs but swapped them back when it continued. The new one as been fine since I swapped out.

 

Please do

Do you know how much power can be run through a oe filter and air box?

 

How long has your AEM been in?

Siv

 

I put it in when I started the thread, but I've had the engine out since then. The AEM does have alot of induction noise, so I suspect it pulls alot of air.

 

Ok
Im still considering my options and I do like the AEM.

This is interesting though.


Siv

 

Some great stuff on this thread from the Legend Harvey Smith.

https://forums.sidc.co.uk/topic/1593...map-confusion/

Hi Gaz, do not believe all the glossy advertising and folklore that you can read on various forums, this one included. Some years ago I did a series of tests on the rolling road at TEG Sport, Carnforth, with Steve Simpson. The car in question was my STi Wagon which at the time was lightly tuned with a Simtec ECU running with the standard airbox, 440 injectors which were close to maxed out, one of my Hybrid front mount intercoolers, my ported headers and matched uppipe and 3" exhaust.

The filters tested were a Green, foam, HKS panel, the OE filter (cardboard), K+N panel and STi which had a cotton wool type filter medium. The spread on the power output from "best" to "worst" was 1.8 bhp. The problem with the green foam was that it allowed through particles the size of sand grains. A new OE Subaru filter and a K+N both produced the same power and were good at filtering. The problem with the OE Subaru was that it would need changing every 3000 miles or so. The STi filter which was disposable and by far the most expensive had the least power output but the best filtration. The spread of results were from 334 to 336 bhp (HKS Green foam which I will not use). The OE cardboard is good but needs replacing frequently so I settled ont he K+N that I can clean and oil several times between service intervals at minimal cost.

Like I said, glossy advertising regularly tells lies to bull up a product eg. BOVs that add power or improve accelleration, turbo timers that are not required, exhaust systems that add 50 bhp and other bull****.

Now some time later in one of the Subaru dedicated magazines I saw that Scooby Clinic repeated the tests, similar to me above, and the outcome was similar to the results above. So two individual sets of people have carried out these tests and come to the same conclusion.

FWIW, on a Classic I will stick with the OE airbox all the way to 340-350 bhp and on a New Age to somewhere between 350 and 400 bhp.




Siv

 

This is why my Mishimoto cold air intake and filter is still sitting in its box 2 years on.

 

I’m like you, filtration is more important than flow.

Whats the trade off of sticking with an OE filter?.... 1-2 bhp maybe.

The more I read the more it makes sense to keep the OE filter.

...... lol

Siv

 

If OE filter is good enough for subaru then it`s good enough for me.

 

i run a k and n in mine , i was expecting no extra power it’s just easy to clean , a change of induction system to a cone filter plus a remap would probably have a minimal impact they say if it’s less than 20 bhp increase in power it’s not that noticeable , driving a car on a hot then cold day would be more noticeable , i had a cone filter before but i did not like all the constant extra noise that came from it so went back to a panel filter

 

Taken from a thread on NASIOC in the states.



#4
05-18-2015 09:48 PM by kaczmarz
I have a big problem with my AEM (K&N) DryFlow panel filter!

I have switched from K&N oiled one to AEM DryFlow about 4 months ago.
I cleaned the air box with alcohol, and MAF with CRC MAF cleaner at the same time.

After a month, noticed on my AP that my LTFTs were negative which hadn't ever happened before since my pro-tune two years ago. Gradually, over the next couple months, LTFTs became more and more negative.

Once they reached -18% I started investigating:
- A car doesn't take any oil (never had),
- No smoke from the exhaust,
- No smoke from the oil filler neck,
- Installed Crawford AOS - so its not PCV valve,
- No pre- front O2 sensor exhaust leaks (had to remove wrap),
- Installed new front O2 sensor,

Finally, I ordered a new MAF sensor, after one of the members here had identical symptoms (large negative LTFT) and fixed it with a new MAF.

In the meantime, I haven't even considered cleaning the MAF since it was cleaned just four months ago and now I have DryFlow filter!!!

But being desparate, I decided to clean it, hoping for it to get at least a bit better while waiting for a new one. Of course, I didn't have MAF cleaner(because now I have AEM DryFlow filter!!!) so I just soaked it for 15 min. in isopropyl alcohol. There'was no dust or sticky residue inside the air box.

Today morning, I reset ECU, started a car, and started driving before my LTFT become too negative. To my surprise, they actually started climbing up!
Now they are in the +1 to +7 range, which hasn't happened for the past two months.

I tried to find somebody else who had a problem with AEM DryFlow filter rather than ********** to it and I found this blog:

http://forums.fourtitude.com/showthr...-possibly-more

Apparently, dust from the AEM filter attaches itself to the sensor.

So Good Bye AEM piece of $#@t!

Going back to K&N oiled filter which I had used on my car for 5 years before, never having problems with clogged MAF.
Siv

FWIW the OE filter is the only one that I can’t find negative feedback for.
From what I can see the K&N is the best aftermarket panel filter, as long as it’s cleaned and oiled properly.
I had one in my forged blob, I never cleaned it and it was in the car for 20k post build without issue.

Siv.

 

Got to say, I ran K&N in my hatch for 28000 miles, no issues

 

I think I would be happier using the K & N, I will stick with the oe filter until mapping day.

Siv

 

The Gen 4 Legacy OE Airbox and filter are the same as fitted to the Hatch/Saloon STI's - I would expect at least 350bhp.

 

It goes without saying that we all want the best results from a re-map.
will the Oe filter be ok?

Siv

 

Having met Harvey a couple of times I wouldn’t hesitate to agree with what he says here.

The OE filter is as good as anything out there.

Siv

 

seem to recall i mentioned similar a while back............

 

you said this on my other thread.
"nothing at all wrong with K&N as long as you ensure its not over-oiled"

I assume your perfectly happy to endorse the oe filter too.

There are also people swearing that the cosworth is a really good filter.

and the aem.......... and the pro r ..... and....and and lol



Siv