a more technical question ?

[Porsche911r101]

first of all, happy birthday JW!!!

Secondly, I was reading about the Lamborghini Murcielago, to find it has a "external noise reducer" that you can set for journeys. Ive tried to find out about this as im intrigued as to how it works and if possible to duplicate it, reason being my golf has an extremely loud exhaust and i love the attention i get from it, especially girls, as it has, IMO the looks to match, and they seem to love it, anyway: i dont love the noise so much when i come home at 2am and wake up my whole street, nor when i start it at 7am and again wake up the whole street, and it can give me a headache on long journeys.

so is anyone able to tell me about this ?

I hear ferrari has some kind of butterfly in the downpipe that remains semi closed on idle and low acceleration then opens up on full throttle ????

[No.1]

Many cars have butterfly valves that open at higher RPMs, but it is computer controlled, so theoretically, you should be able to set the point at whatever RPM you desire.

One question, though. Why do you have this x-zorst on your car? Does it provide more power or is it just to mae noise?

And relying on an x-zorst to get attention to make yourself feel good is a little lame IMO :bah:

[Porsche911r101]

its for noise i like the noise but im respectfull of people ie i wont boot it when old grannys are around, im a cruiser not a boyracer, and im sorry but i dont have mega money for anything better at the moment... im only 19, i work hard at uni in hope for a better car, but i might aswell enjoy my current one.

do you have any idea where ferarri get their butterfly valves from, or where to make them ?

[RC45]

An electric cutout is what you are talking about.

Simplest design has a stock mufflered exhaust system, with a cutout dump pipe. This pipe is capped by a solenoid controlled butterfly valve.

Flip the rocker switch to modulate the opening.

[Porsche911r101]

yeh i know what they are but thats not what ferraris etc use, they have a butterfly valve in their system that opens only partially reducing the sound somehow, then opens fully at a certain rpm or WOT.

[saadie]

just stick a half banana, sliced down the middle, in the exhaust

[Porsche911r101]

LOL or not hehe

i stuck a bottle down it once and it didnt alter the sound, just popped out when i revved.

think i might have to email ferrari and lamborghini about this one

[RC45]

Originally Posted by Porsche911r101 yeh i know what they are but thats not what ferraris etc use, they have a butterfly valve in their system that opens only partially reducing the sound somehow, then opens fully at a certain rpm or WOT.

Actually that is exactly how all the systems work.

You either dump to the atmosphere letting the gases bypass the rest of the exhaust system and also slightly reducing the back pressure, or you close a valve in the existing system significantly increasing the back pressure.

This type of system is not really for 'sound gains' but is a way to manipulate the power band of the engine by exhaust pulse and back pressure tuning.

These systems are integral to the engine management and design and not a backyard project ..

So - in short, considering you already butchered your cars exhaust system, you would be better off simply putting back the stock muffler and installing an electric cutout upstream that you then open when you want noise..

[Porsche911r101]

Ok thanks

I found exaclty what im looking for here :

http://autospeed.drive.com.au/cms/article.html?&A=2291

[saadie]

yep thats it ..
they banana wouldnt cost that much tho

and hey .. after every ride .. you will have a baked banana to eat lol