Tim(e)

Can anyone recomend the best Induction Kit for a 2004 STi?

Was out in friends EVO 9 MR FQ 340 with an HKS fitted and you could really hear the suck from inside the car and a blow off type sound where the air is being released back through the filter. I would like to replicate that if I can?

Cheers

a16pse

if you fit one make sure to get it mapped but most mappers will not recomend one unless your going for big power mate, its a shame as i also would like the noise but i took their advice and fitted an after market panel filter..

TonyBurns

iTrader: (3)

Replace standard air filter with a green/cosworth etc air filter, you dont need an induction kit to suck all that hot air back into your engine when the standard setup is very good

Tony

LegacySTi

iTrader: (13)

remember cosworth ones are throw away.. as in designed as upgrade to factory oem at service intervals..

mikescooby

iTrader: (2)

http://cgi.ebay.co.uk/SUBARU-IMPREZA...item27aab83e6a

i bought this one for my03. it fits between the inner and outer wing.

RS74

stick with panel filter don't need indution kit . unless your running very big power, i'm running 380 bhp with panel filter . will need remap as already mentioned due to maf don't like indution kits

Splitpin

With the best will in the world, your car will run better on the standard bits than that stuff. OP has already received the best advice.

ScoobySteve69

iTrader: (13)

Oh dear

aXeL

Hi All,

I'm going to be the proverbial fly in the ointment and suggest that it would appear that, while it's prudent that everyone has highlighted the risks and lack of power gains, no-one has really answered the OPs question.

YES! You will get the nice noise. Done this myself by making a closed insulated cavity in the engine bay with a GGR cone filter which can pull air from both the wing and the front of the car. I had to tweak my AFRs and the MAF scale slightly as the car began to lean (and knock at the top end) as it was drawing more air under heavy load, i.e. it definitely made an improvement but I could only detect it through my logging runs. Couldn't actually feel the difference though.

And the noise? - Spot on! I can actually hear what the airflow is doing now..

mikescooby

iTrader: (2)

whats up bro.

i had mine mapped and afterwards i could hear boost surge from the filter, suckshen waving up and dow. so got it tweaked, job done. but i could still hear a slight suckshion tone wave, so i asked the mapper to see if he could see any little dipps in the graph

NEILB1

iTrader: (9)

i am still desiding what filter i should go for, THINKING MORE replacment, Pipercross or something

richie001

iTrader: (3)

K & N

NEILB1

iTrader: (9)

was also looking into that as well

ScoobySteve69

iTrader: (13)

It`s just my opinion but I personally wouldn`t pay so little for something so important on a performance car. Maybe it`s psychological but I do believe `you get what you pay for`

dynamix

iTrader: (3)

It could also be that a slight variance in the maf tube diameter has skewed the readings of airflow and therefore leaned it out due to that.

Tim(e)

Thanks for all the responses I fitted a JDM HKS panel filter for the minute. Left the clips of the airbox for a slight blow off style sound...

Still want more noise in the cabin though.

Whats the resonator box removal mod form the front wing? is this restrictive to airflow? I assume its a silencer of some sort? Is it easy to remove or cap off?

jura11

iTrader: (7)

HKS its not best panel filter(because its not reusable),if you look for panel filter try K&N.I have on my WRX 2001 induction kit,and never have problems with MAF.If you want more noise just look for AEM.
If you want remove resonator,you must remove front bumper and here is guide:
http://www.scoobypedia.co.uk/index.p...sonatorRemoval

Tim(e)

Oh? I thought any aftermarket panel filter was a lifetime cleanable job? The only one that is disposable would surely be the OEM Subaru filter?

Thanks for the link but I dont understand how this changes anything? It looks like this box is an airfeed to the filter form the front bumper? Surely buy removing this you are reducing airflow to the filter?

TonyBurns

iTrader: (3)

No, there are several disposable ones, the uprated STI one, the OEM and the Cosworth one, and tbh, I would go with these over the reusable ones.

Tony

Tim(e)

Right...

If I am considering 350bhp plus what is the best induction kit and where can I get a resonator delete elbow? What do you do when you take the resonator box out without a delete elbow? Does the air just swirl around the inner wing?

Is it ok to do this mod with an elbox link pipe fitted?

What is the throttle coolant feed mod? And how do you swap rear lights to look like JDm ie round bit becomes lights and square bit becomes brake?

joz8968

iTrader: (13)

For 350bhp, the OEM trunking with a decent panel filter still suffices.

I have a MRT all-metal res. delete pipe, that I don't need. It's for a MY93-96, but don't know whether it's suitable/can be modded to work on a 2004 car??

Splitpin

Do not delete the resonator if you have a MAF-based ECU, it is counterproductive. It may have a silencing function but it also improves mass airflow measurement accuracy by reducing turbulence in the inlet air. Both Harvey and myself have tested this (properly, not "butt dyno") and found it reduces mixture consistency, and power.

joz8968

iTrader: (13)

Interesting SP.

I didn't realise an un-mapped res delete mod would have such a profound effect on MAF readouts (not that I, myself, would fit a res delete mod without a remap tweak, anyway ).

L.J.F

iTrader: (31)

Mate you are best off just using a Green cotton panel filter, they last a lifetime and you also notice a audible sucking noiser under load Do not bother tinkering with induction kits because your next thread could very well be "where should i go to get my engine rebuilt". It will cost you roughly 1300-1500 to get cold air induction kit and simtek ecu mapped, thats the only safe way to do it and it really aint worth it just for a hks style induction noise!

Alan Jeffery

It's worth re iterating what happens when you fit an "induction kit" or make any other change to the air intake system.
The mass air flow sensor (MAF) is designed to allow a measurement of air intake volume.
Varying air flow through the MAF will give a sliding scale of voltage outputs. This is done to allow the electronic control unit (ECU) to make calculations based on engine load.
The ECU constantly monitors various sensor inputs, based on engine speed, load, temperature etc, then provides a very specific output for ignition timing and fuel injector duty etc.
Having limited intellect, the ECU can only react based on sensor inputs, so if a change is made to the air filter system, the voltage output from the MAF sensor can vary considerably, and the ECU will then do "this" instead of "that".
Even just leaving the clips loose on the air box can directly alter ECU outputs.
As a petrol head I agree that the sound of an engine is important.
If you are going to take the route of car modifying in order to achieve aural nirvana, you have to take on board that sometimes there is a nett cost involved.
Paying someone else to professionally deal with the implications of air filter fiddling may be a small price to pay compared to the misery of engine damage.

Splitpin

You'd be surprised how much of a difference a seemingly subtle change can make, especially given the way airflow meters work. As Alan says this is not an area to muck about with without expecting consequences.

The ECUs contain an error correction system designed to smooth out some fluctuations in the MAF input, but without the resonator, I found the raw signal became significantly more "jagged", to the point that there was problematic spiking even in the corrected value. In practice, had I kept the res delete, I'd have needed to run a little bit more fuel to ensure there was safety margin enough to cover the leaner spikes.

I guess there might have been the option to recalibrate the error correction algorithm to smooth things out a little more effectively. In practice though I'd rather have the more accurate sensor input in the first place than increasing the amount of correction (i.e. averaging/guessing) the ECU can do.

Tim(e)

Just ripped that resonator out. Also swapped the brake and rear side lights for the JDM look!

Didnt notice any noticeable drop in power but I was expecting much more noise....

Ill get the GP delete elbow and fix that in sometime.

Splitpin

What's the problem here, the amount of noise the car is making, or your "expectations"?

I think the power drop Harvey noted was something like 6bhp, and it would be surprising if you did notice a change of that magnitude. The bigger problem is the inconsistency of airflow measurement. It should be covered by the safety margin in a standard ECU, but it's undesirable nevertheless.

Modifying your car in a manner that makes it run less optimally in pursuit of "more noise" seems to be putting the cart before the horse a bit.

Tim(e)

Not really as I am new to Subarus and turbo'd cars in geeneral its called the honeymoon period where I will try simple free mods and discover for myself what they really do. Its a learning curve...

But we all love noise though...

aXeL

True, that would also help account for it flowing more air - still, not a bad thing.