User 11121

I've been wanting to ask this question for a while.
My .2 GT3 which happens to have a SharkWerks center muffler bypass, sounds incredible during cold starts when I fire her up once a week (while I ignore the occasional Smoke & Grinding noise - read more here). The exhaust note is Meaner & much Louder with zero input from throttle, just idle (Plus keep in mind Sport mode is Off. When Sport mode is On it's intoxicating). However after approximately 30 seconds she quiets down to normal idle noise.

1. Why is that?
2. Is it simply higher RPMs during cold start? (if so, why can't I replicate this sound with additional throttle input)
3. Are there additional exhaust valves that are only open during cold starts?
4. The real questions is how can I make my GT3 sound like that all the time? For me it's like having the car in BEAST MODE, but only for a few seconds. : (

Any input is highly appreciated.

Shivatron

On cold starts, the ECU richens the mixture, retards the timing, and runs the secondary air pump in order to heat the catalytic converters as quickly as possible. A side effect of this is some wasted energy (noise) in the exhaust system. I guess you could reproduce it with an ECU programmed to retard the timing full-time, although I'm not sure you'd appreciate the power loss...

MarkD

it's just excited, like a puppy that hasn't gotten out to play in a while

yes, you can have that full time
I can't find the thread, but there is a plug on the right side in the engine compartment.
Unplug it and, voila!, more noise.
Need to find the pic, it is easy to get to

This opens the solenoids that control the flaps in the side mufflers, causes them, to be open full time
They are vacuum operated... so if the car sits, the vacuum bleeds down over time

wait, you said this lasts 30 sec?
See above post by Shivatron, this is emmisions stuff, doing it's part to save the planet

Still, you can have LOUD full time by pulling that plug

RAudi Driver

Pulling that plug still won't give it that same sound as when it's cold.

MarkD

right, but it will be significantly louder than without.
Won't be as crisp/crackly

User 11121

I see. Was under the impression that it was a simple valve or exhaust flap causing this wonderful symphony during cold start idle. Unfortunately, the only way to experience such acoustic bliss is on open throttle above 5K RPMs + Sport mode. However I was in search of the sound without the excessive speed.

Sort of like the F430 Scud. That thing sounds like it's racing, while stopped at a red light.
If anyone has found the thread mentioned by MarkD, I would appreciate it.
Otherwise feel free to send additional tips my way.

BTW, this is not a complaint of the GT3, it's my way of experiencing more noise of this fantastic machine.

cds4402

FWIW, my M3 does the same, and it has no fancy exhaust flap. Usually takes about 20-60 seconds to settle down into a normal idle depending how cold it is.

paver

Dewuser, just search the GT2/GT3 forum for "exhaust valve". I actually posted a link to it for another thread here last week. It's easy to find.

MarkD

here: https://rennlist.com/forums/7273531-post22.html

unplugging this will make it louder, full time
a bit different than the cold start... but may get you what you are looking for