I am so very sorry for asking this, but as a new Subaru owner, I really dont know that much.

Not too long ago I bought a 2004 STI form a good friend of mine. No problems with it at all, other than the bills for oil changes and break pad wear.

It doesnt get driven that much as I am a little paranoid about it getting nicked, so it rests in the garage during the week, only to make brief outings at the weekend. (cant wait for the snow!)

A guy at work told me I should 'get a dump valve' for it.

My question is does it make any difference other than sounding good???

Its a 2004 2.5 litre STI, standard as they come. Although I will get a K&N air filter for it this weekend....

Any help greatly appreciated!

By the way, its a great driving car, even with the big wing and tupaware interior!

 

Asked the same guy and he explained.

All about reducing back presure so the turbo can spool up again quicker....?

Might have to get one, any suggestions on cheap and easy to fit models?

 

They come with a standard recirc one that does the job every bit as well without the sound Best off leaving it alone

 

You,ll already have a re-circulating dump valve as they are stndard! Aftermarket ones are not needed really unless you want to make a noise! (it actually decreases performance if anything)

 

Thing is - I have heard some cars with these things on and they sound like fairground rides. Really - And I MEAN Reallly stoopid. I am all for allowing the Turbo to spool up faster but I'd want a silencer on the dump valve personally.

 

Are you sure it's a 2.5?

 

US model 2.5 litres

 

OK ta should have looked ...!

 

So general consensus is leave it alone. It works fine as is so I will save the money, thanks.

What about a cold air filter??

Also I am interested, everyone on the formus says run it on 98 octane, but we only have 93 octane here. (The fuel cap dose say nothing less than 93)

Are there different ratings for US fuel and UK fuel?

anyone want to send me a can of 98 for me to try?

 

93 (octane) / premium is equivalent or slightly better than our 98RON fuel. Just differing methods of calculation.

HTH

Steve

 

I could be wrong, but don't think UPS will ship that....lol!

 

As the others have said, if you don't want an aftermarket DV for the noise alone, then you don't need an aftermarket DV full stop. The standard recirc is the best option upto and over 350bhp, where higher boost levels may necessitate a stronger unit. If you want the turbo to spool up quicker you should consider removing the cats from the exhaust, but this must be done with a remap of the ECU to prevent possible DET.

When you say "cold air filter", do you mean an induction kit ?? Again, these can often reduce power and lead to many other problems. They are known to destroy MAF sensors due to excessive vibration, and can often supply your car with much warmer air induced from the engine bay. Along with your K&N panel, you could consider the resonator removal (often called the snorkelectomy in the US) which involves removing the ram-air (God only knows where it gets the air to ram ) scoop from the front left of the engine bay, and the resonator (which is just a big plastic bottle which silences the airflow) from the OS/F (NS/F in the US ) wing (fender). This will feed the car with a better flow of air from the cool wing (fender) area instead of struggling for air from the hot engine bay. Makes the air induction and recirc dump valve a bit louder without it sounding like a "fairground" too

 

US 2.5 is N/A isnt it??????

 

Yes its a 2.5 litre over here, which I am told helps to reduce turbo lag, and to me there seems to be very little, particulalry compared with the WRX and the new Audi 2.0T.

Dont know why its a 2.5 as opposed to a 2 litre in the UK. The specs are the same 300hp and 300lbs.

General consensus seem to be that a 'Dump Valve' is not needed, and a 'Cold Air Induction kit' sounds like a bad plan in the long run.

I will ask about a 'snorkelectomy' when I but the K&N filter, but probably wont play around with it too much. I might look at an exhaust one day, but nothing too noisy.

Thanks for all the help though guys!

 

Sorry, yes you can get a 2.5 normally aspirated Impreza model here, but its only 160hp or similar. then you can get the WRX with a 2 litre turbo and then the STI with 2.5 litre turbo.

All flat 4's. Although there is a rumour of a 3.0 litre flat 6 coming out aparently.

 

Standard factory dump valve on that car is as good as anything else (better actually).

Bob

 

Pilotdan, US cars used to be bigger capacity than other similar models around the world because of all the ' creature comforts' necessary for the USA market.

Power seats.
in fact Electric everything
Air con
Auto trans
Power stering
etc etc

It used to absorb so much power that an increase of at least 10% in engine capacity was necessary to maintain any sort of power and performance.

I am serious.

Hear, hear, to the dump valve advice above - leave it well alone !

David APi Engines / APi Impreza
www.apiengines.com

 

i tort this was a bumper

 

Maybe I don't speak American

 

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