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The mkiv Supra Owners Club

Exhaust butterfly valves


hodge

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Hi folks

I'm wanting to fit 1 of these to my exhaust to quieten it whilst pulling in and out my street. The night I returned from my JP Photoshoot I didn't get home til 1AM. As you can understand the car is pretty loud and 1 of my bust body neighbors took it upon himself to phone the police telling them I sat on the drive for 30mins revving the car at 1AM bloody idiot.

So anyways just to keep the piece if I fit an electronic butterfly valve in the exhaust to quieten it down when I'm in and out the street that should keep everyone happy I recon.

A few questions really.

 

1) Do the really quieten down the exhaust by A LOT??

2) where's best in the system to put it ??

3) And can someone reccomend me good one ??

 

 

Thanks

John

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Want an electronic one. Cant be araed to get out the car and put a bump in and out. It means I'll have to drill my tailpipe n that ain't fount to happen.

 

Think I know which neighbor it is. Every other one hasn't got a problem with it.

I'm going to approach him about it as soon as I can. Can't see the issue in just knocking on my door.

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Just adding the valve wont do much, you need to do it like Dandan did to have any decent effect, add in another silencer or two, use the valve to open up the exhaust under the car.

 

http://www.mkivsupra.net/vbb/showthread.php?194439-Dan-s-Supra-Project/page27&highlight=dandan+exhaust

 

I've got no issues with flow to want to exit it under the car and I don't really like the sound of an unsilenced exhaust just sounds like its blowing. If I was doing that I may as well go for a 3" system from the downpipe and put the valve on just before it.

It's just to quieten it down going in and out the street.

 

There going to love me when I fire Kevin's car up at the weekend to bleed the engine off lol.

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I had a valve in my Soarer. It was around 102db without the valve and 93db with the valve closed, just to get under the 94db limit on track days and the open the valve when I went to the track ;) Couldnt boost with the valve closed over 1 bar, there was too much back pressure in the exhaust that way.

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I've got no issues with flow to want to exit it under the car and I don't really like the sound of an unsilenced exhaust just sounds like its blowing. If I was doing that I may as well go for a 3" system from the downpipe and put the valve on just before it.

It's just to quieten it down going in and out the street.

 

There going to love me when I fire Kevin's car up at the weekend to bleed the engine off lol.

 

Numbers are from this post... http://www.mkivsupra.net/vbb/showthread.php?194439-Dan-s-Supra-Project&p=2768301&highlight=decibel#post2768301.... my setup works well to chop a lot of noise out, especially low speed cruising around town and the neighbours. With the butterfly open I have one 4" straight through silencer which adds a bit of "tone" and takes the flat booming and dead sound out of an unsilenced pipe.

 

Exhaust bypass valve closed - quiet mode:

1000rpm - 83.5dB

4000rpm - 90dB

5000rpm - 96dB

 

Exhaust bypass valve open - noisy mode:

1000rpm - 90dB

4000rpm - 91dB

5000rpm - 101dB

 

Seen as the 4" dumped portion exits under the car I thought I'd try a test a little closer to its exit. The following were taken just in front of the rear right tyre at about 100mm above ground level and about 100mm from the side of the car.

 

Exhaust bypass valve open - noisy mode:

1000rpm - 89.3dB

4000rpm - 99dB

5000rpm - 103dB

 

"On the move" it's even quieter than the static numbers suggest - perhaps I should do some drive bys at the weekend :D

 

Edit: I don't have any first hand experience of valves fitted inline (as opposed to a bypass like mine). I can imagine they would help the noise but you'd want to avoid high boost if the valve wasn't fully open. My one is a DMH which comes with a 4year guarantee.

Edited by dandan (see edit history)
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Numbers are from this post... http://www.mkivsupra.net/vbb/showthread.php?194439-Dan-s-Supra-Project&p=2768301&highlight=decibel#post2768301.... my setup works well to chop a lot of noise out, especially low speed cruising around town and the neighbours. With the butterfly open I have one 4" straight through silencer which adds a bit of "tone" and takes the flat booming and dead sound out of an unsilenced pipe.

 

Exhaust bypass valve closed - quiet mode:

1000rpm - 83.5dB

4000rpm - 90dB

5000rpm - 96dB

 

Exhaust bypass valve open - noisy mode:

1000rpm - 90dB

4000rpm - 91dB

5000rpm - 101dB

 

Seen as the 4" dumped portion exits under the car I thought I'd try a test a little closer to its exit. The following were taken just in front of the rear right tyre at about 100mm above ground level and about 100mm from the side of the car.

 

Exhaust bypass valve open - noisy mode:

1000rpm - 89.3dB

4000rpm - 99dB

5000rpm - 103dB

 

"On the move" it's even quieter than the static numbers suggest - perhaps I should do some drive bys at the weekend :D

 

Edit: I don't have any first hand experience of valves fitted inline (as opposed to a bypass like mine). I can imagine they would help the noise but you'd want to avoid high boost if the valve wasn't fully open. My one is a DMH which comes with a 4year guarantee.

 

Great info thanks Dan. I'm not sure what direction I'm going to go with this but it's looking like an inline valve I think and maybe a silencer also. I'll keep you all posted.

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