WrxSti03

Has anyone removed the intake silencer on there STi?
Any pro's/con's to this? Want a bit more turbo noise but don't want to sacrifice any ponies!
Looked into this on the forum but can't find any hard proof you actually do lose bhp by removing it.

Thanks.

John.

bludgod

iTrader: (3)

made no difference to the power output on my bug WRX with a 16g - you can seal off the elbow using a piece of the original box you've hacked off so that it's only sucking in cold air from the front of the car via the normal under bonnet scoop.

Linksfahrer

You won't lose top bhp , as your turbo will continue to spin/charge till you get to target PSI , but you might lose spool up rate , to check your intake modification changes ( "flow character" ) you would have to look for changes in the graph for torque level on a dyno , particulary at lower rpms. However for best results road test "dynamically". I would personally try to find an air intake that is fairly short & minimised twists and sits in the coldest air you can find. Anything inside the engine bay is bad news.

An intake from under the front edge of the bonnet makes sense to me,
but your bound to see an exagerated variation on a dyno with a blower up front as the air temp while standing during roller testing will be higher & density lower than when driving. ( try dyno test with blower & bonnet opened v closed you will see the difference ).

The advantage of taking air from the side of the engine bay (Subaru design takes air from over the drivers wheel arch) is that the air is drier , while some moisture "mist" will actually help charge temp & density thereby increasing o2 content a complete soaking of the charge air with large water droplets (rain wheel spray) will eventually reduce power as your filter gets wet clogs and a non burnable mix will just cause cough and splutter.

If you must have Turbo noise , then fit an aftermarket BOV ,
personally I prefer the crackle out of the exhaust and the occasional flash as the unburnts light up the night.

WrxSti03

It did have a bov on when I brought the car but put a oem recirc on as soon as I got it home.
I was just wondering with the resonator deleted if would help breathing better as I'd imagine the resonator would be quite restrictive...

I'm getting the car mapped the end of this month and I'm just going to throw a green panel filter in.
Might go for an induction kit if I decide to go front mount intercooler at a later stage.

John.

Linksfahrer

Gas flow in a combustion engine and tuning for power is a lot about inertia , flow restrictions are only restrictive when the volume of gas / air intake that you can pull in for any given vacuum level are less than the amount of air required for the volume of fuel your cylinders are able to take , this is a function of cubic capacity or effective capacity above atmospheric ambient pressure , under forced induction of our turbo engines.

Basically if you have enough air for the given rpm / air fuel ratio you will not have a power restriction. Sometimes just preventing the odd rough edge in a pipe can significantly reduce eddy effect and this keeps gases moving even
at slow flow rates and a better pick up is achieved when you call for power when you open the throttle. Mapping the engine just makes the best use of the available air , your efforts to make enough of it available gives the tuner his chance to find the best power/torque. Most of the time we should be looking for the biggest restriction to flow , and unless you have a bigger turbo , then you will find this in the exhaust design and the head / valves first as you can only flow in what you can flow out.

Linksfahrer

The larger intercooler ( than Sti) is really only a benefit if you go for a bigger turbo , the filter is probably also not much help either until you go looking for over 300 bhp , Id spend the money on a good exhaust before the filter/or IC prior to re-mapping. I think you should maybe take a look at Andy Forests site he has a step by step on tuning stages , this helps show you what makes power and what mods you need in a logical order.

http://andyforrestperformance.co.uk/58901.html

WrxSti03

Yeah I've got a sports cat and second decat plus unresonated mid pipe and back box. Green panel filter, uprated fuel pump. So hopefully will see over 300bhp.

WrxSti03

P.S car is a 2003 STi.