ScoobyLee2000

Hi All,

Whats the best direct replacement air filter you can get? Does it really make a difference to the performance?

MY55 STI

Cheers

SL

Rossyboy99

it for me in previous cars has increased throttle response and sounds a little better it claims to up bhp but dont count on anything more than 2-5 i'm going for apexi but the choice is endless with multiple views on all.

davedipster

The factory fit paper item is rather good.
I fitted a rather expensive green filter and saw no performance change at all, and was concerned over its filtering ability. So back on with the std paper.

dipster

danfranklin1

I can't really rate K&N's replacement filter - very poor fit in the airbox of my Classic. It was a major struggle to get the top back on - had I known it, I probably wouldn't have bought it.

AndyMoody

iTrader: (2)

I bought an Apexi one from Temple Tuning as mine needing replacing in my 03 WRX. Many opinions on what is best if you do a search. STi OEM one is OK so up to you if you want to spend dosh when it probably won't make any difference or needed anyway.

Andy.

AlanPPP

iTrader: (2)

Use the one they spent millions developing...

The standard one Or at best fit as better flowing panel filter

JohnD

iTrader: (5)

Not too sure about the "millions" bit! It's a bog ordinary standard paper filter element that also happens to fit a number of other cars! My low mileage standard filter is now doing a fine job in the wifes Nissan Primera! (no, I didn't charge her for it!)

JohnD

ScoobyLee2000

What about Pipercross?

Butty

iTrader: (2)

A standard air filter replaced every couple of thousand miles.
Nick

Alan MaC

J&R Panel Filter.

Good for 80,00 miles plus.

Around 3-5 BHP gain.

Needs to be cleaned with a soft brush from time to time.

The only problem is, re oiling.

Too much oil & it comes through the MAF sensor.

Apart from that, a goood investment.

Regards.

Alan MaC

Mikkel

Mine has a Simota panel filter. No noticeable difference in power but it appears to be doing a good job. Got it free from scoobyworld when I bought an exhaust. Use it so I don't waste money at service paying over the odds for paper when I can just clean the Simota one every now and then.

mgcvk

Had a green one before got a blue one at the moment. You hear the induction with these so presume they must be less restrictive than the standard item.

Mikkel

The blue one looks like the one I have. Fits perfectly.

Daz1121

The green panel has worked very well for me on my Classic

L.J.F

iTrader: (31)

i also use a green cotton panel filter, it less restrictive than the standard one!!
its really a case of finding out for yourself which one you prefer!!

corradoboy

Professional testing by Prodrive, quoted on here by Mike Wood, and independent testing by SNet's own Harvey found conclusively that there was no gain to be had from any aftermarket filter, and that the OE paper item is pretty much the best for the job. I used to run a JR Racing and considered it very good, but I didn't dyno test it before and after. Concerns were raised over the filtration properties too, but no real testing has been done by Prodrive as once they had proved there was no performance gain testing was abandoned. Whilst Harvey was testing he also checked the advantages of the 'snorkelectomy' (intake resonator removal) and found a slight drop in power with worrying AFR readings. Although I never read the article, some reported on here that a Subaru magazine also found the same results for the air filters, with the STi item coming out worst.

ScoobyLee2000

Hi All,

Cheers for all your comments...

I have decieded to fit a Pipercross Panel Air Filter. Am a bit concerned about fitting based on the oil affecting the MAF sensor.

The seller of the filter recommended not putting oil on the filter and run it dry, but this I am sure will affect filtration!!

What do you think?

COLZO

As said before, Prodrive keep the standard paper one for their PPP as there are little or no performance increases.

fivetide

iTrader: (1)

Again, why fit something that you are concerned will damage your car - at great expense when the standard one is fine.

I checked with Andy F before the remap i had if getting a filter would help and his reply was not one bit - and that's with a remap so there really is nothing to gain.

If you want to improve airflow get a samco intercooler hose kit. The standard one is restrictive so it will help cooling and performance.

5t.

harvey

iTrader: (48)

Four filters were tested on Dyno Dynamics rollers on the same afternoon in fairly quick succession. Fan cooling on the dyno was not an issue and similar inlet temperatures were achieved before starting each run.
As the results were not in line with expectations, the experiment was repeated the following afternoon with exactly the same results in that :
The difference between "best" and "worst" was less than 2 bhp on each day.
The order of performance remained the same.
The removal of the snorkle resulted in a small but clearly noticable drop in power. From memory it may have been 7 bhp on a 335 bhp car. The drop was the same each day.
Mike Wood of Prodrive kindly confirmed these results were in line with their findings which then stopped further claims of huge power gains from a filter change.
Subsequently, tests were done on the filtration ability of the filters. The green sponge HKS pannel filter let large particles through but it had produced the highest power figure each day. The standard Subaru item and the lightly oiled K+N produced similar power figures and both filtered well. Last in terms of power was the disposable STi, remember, last by less than 2 bhp over a filter that had poor filtration qualities and the STi was probably able to filter the smallest particles.

If I am keeping a car I will run K+N simply because it can be cleaned and reused frequently. Otherwise it is the O/E Subaru pannel.

I have for sale, £20 each, an HKS Green sponge pannel for Classic and Simota, Blue pannel still boxed and unused.

Bob Rawle

Was the car remapped to suit each filter as it was changed though to give the same afr ? Have to say I know what I like to see on a car when it comes for a remap. Std filter is the last thing I'd choose to use. You need to find the absolute limit for each by mapping to judge true performance, if the fixed test level is set too low than all filters could support it and really 2 bhp is measurement error.

cheers

bob

Northern Nick

iTrader: (1)

IMO,

Panel Filter - Green WRC cotton weave

CIA - APS

harvey

iTrader: (48)

The car was running the O/E STi 3 ECU and was not therefore remapable.
As the results on the first day were not in line with expectations, the tests were repeated the next day. The difference between "best" and "worst was the same. Less than 2 bhp. Surprisingly the order was also the same. HKS green sponge with highest reading each day. Followed by the O/E Subaru and K+N virtually the same and the STi disposable trailing, by less than 2 bhp.
The test was valid in that it replicated what many owners will do in that they change an induction filter without a remap or even the facility to remap.
There was no discernable difference in AFR which was logged on each of the four dyno graphs on each day however there was a discernable AFR difference when the snorkle was removed.
As these results were generally in line with Prodrive,s findings of which I was previously unaware, I am happy the information provided is relevant..
Obviously mapping separately for each filter may have thrown up slight further differences but that was not the point of the test and please bear in mind that changing the filters had no discernable effect on the lambda values whereas removing the snorkle had a clear effect.

ScoobyLee2000

Thanks for your advise....Sticking to Original one...the best!!