RichieC

Weve had loads about the WRC noise etc but what gives the GpN cars that note? Ive never heard a road car sound the same,but close! I think the closest Ive heard was a guy spectating on the McRae Stages this year (apologies I forgot your name) Is it just the exhaust or does the ECU play a role?

I know the GpN regs dictate the exhaust has to be standard diameter and the downpipe cant be changed (is this true??) but they sound so much sweeter than the majority of road cars (mine for sure). Any ideas?

Regards

Richie

Stef

Do GpN cars have equal lenght headers?
Pete's Scoobysport car sounds unlike most Scoobys.

Stef.

RichieC

No they have the same headers as the road car. The exhaust is supposed to retain the cats (FIA regs) but its known for some unscrupulous competitors to remove em.

ALS wise, its supposed to be a pukka setup, not just a MoTec style air bypass valve affair.
I know GEMS do some GpN ECUs but anybody know who else? Im also told they run 1.7Bar pressure!! not bad considering the relatively untuned engines (compared to GpA/WRC)

So Pete, what setup are you running??

Rich

[This message has been edited by RichieC (edited 09 November 2000).]

Pete Croney

My car sounds very like a WRC. This is down to the manifold. I love the sound

In gp N, no part of the exhaust (incl the tail pipe) may exceed the diameter of the standard exhaust measured at the point where it leaves the standard cat. On an Impreza, this is 2 3/8 inches ID. Gp N rules also state that the car must be fitted with a cat. It doesn't require the cat to be working and many teams punch a hole through the middle of it. Its a bit of a silly rule, as a standard cat will not survive the first stage on a car running anti lag.

MarkF

Richie that was me!! My car (red MY93 WRX) has a standard downpipe, magnex centre pipe with resonator, milltek backbox and the airbox resonator removed. Group N cars, as Pete says, must have an essentially standard exhaust not exceeding the standard size. I think i'm right in saying that most teams will use mild steel exhausts and not stainless because of the weight difference and cost!

RichieC

Aha, its all coming back to me now. I remember now MarkF (I was sat in that red Mk2 Golf on that T-Junction I described last time we had this conversation. )

Sounds marvelous, wonder what the Milltek would sound like on mine with GpA Downpipe and Induction Kit? and then what sort of jump in noise do you get from binning the resonator?

Thanks again

PS What tailpipe does the Milltek come with and how much are they??

Richie

MarkF

Yeah thats right you were in the Golf. My Milltek has a 4" round tailpipe. I thought i saw that they had released other tail pipes but not certain. Binning the resonator (in the centre section?) is supposed to be really loud. Falkland performance warned me that they were pretty obtrusive, probably like a Group N rally car! as they are just a straight through pipe. I think I paid about £190 for the backbox direct from Falcon performance(?) who are the owners of Milltek. Good build quality and sound for a reasonable price.

RichieC

Ive got a Magnex centre with resonator at the mo, and would be interested to see the difference it would make. What change did losing the airbox resonator make (I take it you mean the one in the inner wing?).

Seems very reasonable too, Im tempted

Regards

Richie

Chris L

Richie

I run a Magnex backbox and decat centre (with resonator) and I've also removed the front wing resonator. The real improvement (in sound if nothing else) is when revving and on the overrun - does seem to echo off houses and tunnels quite nicely I heard similar stories about non-resonator centre section being very noisy (can make the cabin very 'boomy' apparantly). A lot would depend on how many miles you are doing in the car - personally I do between 18 and 20000 miles a year, so I reckoned it would be too intrusive.

I'm not planning to do too much more to the car at the moment (MY00), I thinking about an HKS induction system and I've got an intercooler protector on back order from Scoobysport (hint Pete if you're reading this ).

The front resonator is an easy job to do and if you don't like the noise, you can always put it back.

Cheers

Chris

RichieC

Can you give us a run down of how to do it??

Cheers

Richie

Blackscooby

Call me a muppet if you wish ~ but.....

Whats a resonator ?
Whats its purpose in life ?

Don't be too harsh on me !

Chris L

Richie

Can I believe that a moderator is asking that question without doing a search

Give me a couple of minutes and I'll dig out the details.

BlackScooby - the resonator is part of the air intake system. Air is drawn in through the front of the car and then down into the resonator (located in the driver's side front wing) before going through the air filter and into the engine. Its purpose in life seems to be to quieten things down a bit. If you remove it, you can hear the dump valve whistling and you get a bit more induction noise. I'm sure there is a more technical discription, but that's about it.

Chris

Chris L

Here you go:

1. Remove wheel and front splash guard under wheel-arch/front bumper
2. Remove supporting bracket between engine-tub & inner wing (2 nuts; one fiddly!)
3. Remove big black & performance sapping "gourd-like" thing (2 nuts) - this is the resonator!
4. Remove the black plastic piece now flapping in the engine bay
5. Put the support bracket back in & refit splash guard
6. Er.. put the wheel back on.

As in all the best manuals, refitting is the reverse of the above (sort of )

Cheers

Chris (with thanks to the guys who originally posted these instructions)

Blackscooby

Thanks Chris,

As I have a cone filter then it sucks air from goodness everywhere under the bonnet (warm air ???)

I get all the lovely whooshing and rushing of induction roar anyway.

Ta

Mark.

GaryC

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Chris L:
<B>
I heard similar stories about non-resonator centre section being very noisy (can make the cabin very 'boomy' apparantly). A lot would depend on how many miles you are doing in the car - personally I do between 18 and 20000 miles a year, so I reckoned it would be too intrusive.

[/quote]

My MY99 has downpipe, straight through centre (no cat no silencer), and prodrive backbox - I do 30000 a year, noise not intrusive at all, no booming

RichieC

Believe it, this moderator had more pressing engagements with his girlfriend tonight.

Not sure if I want to bother now, I might trial it!!


Thanks for your info

Richie

stratman

I have a non-resonator/silencer de-cat centre pipe fitted, in conjunction with a Sebring back box and dont find it intrusive, sounds lovely..but if anything I would like it louder

Chris L

Gary

You must be one of the lucky ones I was advised against it and I've also heard that some companies won't supply the non-resonator version because of this. However if it works for you then great - do you think there is big difference in the amount of noise produced?

Blackscooby - once you are on the move, the general air flow through the engine means that the air temperature would be similar to that drawn in from an external cold air pipe - so you do not have any issues (I must have posted that comment at least 3 times in the last week )

Chris

Chris L

Richie - - Always happy to help.

Stratman - I sometimes wished I had gone for the non-resonator version, but I made my decision on the advice I was given and I'm happy with it. Might change it sometime if I'm bored though..The only other thing I had thought of doing was going for an HKS filter/induction system. That should improve things a little more without being too OTT.

Cheers

Chris

Dave T-S

RichieC
Not sure you want to bother with the girlfriend???

RichieC

LOL

I posted that this morning post clubbing...am I excused ??

RichieC

LOL

I posted that this morning post clubbing...am I excused ??

Dave T-S

03:01 am - respect - good excuse - excused

[This message has been edited by Dave T-S (edited 11 November 2000).]

RichieC

Talk about comitted to moderating

Id never bin any post that time in the morning, they all make perfect sense....especially P1WR....informative and knowledgable to boot

Rich

MarkF

Richie if your going to the meet tomorrow feel free to come and introduce yourself and we can discuss this further and i'll show you whats done to the car.

RichieC

Cant make it to the meet Im afraid ;(

Thanks anyway, have you got any pics of the car so I can take a gander at the backbox??

Richie

Dave T-S

Richie
And Sunil!???

GaryC

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Chris L:
<B>Gary

do you think there is big difference in the amount of noise produced?


Chris[/quote]

Centre section didn't really increase noise that much, just made it deeper - but i was coming from a cat-less PPP/STiV centre section

Downpipe is a different matter though!!!

Chris L

Thansk Gary - thought that is what you might say See how rich I'm feeling and I might have to go for a downpipe.

Cheers

Chris

sunilp

Chris, get the Downpipe man , single best improvement to the exhaust.

Sunil