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Would this work?
#840888
30/05/2009 03:37
30/05/2009 03:37
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MattW
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MattW
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While I was walking home from town at 3 in the morning I started spec'ing up my next 300bhp Coupe and had an idea that I'd like to try...
Basically, I'd want to put a lever in the driver footwell that switches between cat and decat, so I can choose if I want it quiet or loud and change it instantly.
So here's how I'd do it:
Run a straight through exhaust with decat pipe, put a butterfly valve inside the decat pipe attached to a cable running through to the cockpit. stick a cat converter in parallel so when the butterfly valve is closed the exhaust gases are forced to go through the cat, and when it's open they'll just go straight through (mostly).
What do you think?
How about buying a throttle body and using that as the valve? Obviously, would require some custom welding and fabrication, maybe modification to the floor to make the 2 exhaust routes fit side by side?
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Re: Would this work?
[Re: ]
#840889
30/05/2009 03:47
30/05/2009 03:47
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broadley
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broadley
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sounds like it could work although Im not sure on what effect it would have on the actual running of the car. instead of a cable you could use a solenoid and just have a switch in the dash?
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Re: Would this work?
[Re: ]
#840891
30/05/2009 03:55
30/05/2009 03:55
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MattW
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MattW
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Could do, if someone told me how to do it I think it might be a bit more restrictive than usual running it through the cat due to forcing it round a crude diversion but that wouldnt matter, that's just motorway cruising mode...
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Re: Would this work?
[Re: ]
#840893
30/05/2009 04:00
30/05/2009 04:00
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MattW
Unregistered
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MattW
Unregistered
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Or how about this:
Have the butterfly valve in the exhaust also controlled by the throttle pedal, so have both cables coming off the pedal then going separate ways. the further you put your foot down the louder it gets, and when you release the pedal you can hardly hear it...
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Re: Would this work?
[Re: ]
#840909
30/05/2009 09:10
30/05/2009 09:10
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Joined: Dec 2007
Posts: 2,252 Windsor/ Reading
knight7660
Competition Level
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Competition Level
Joined: Dec 2007
Posts: 2,252
Windsor/ Reading
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there a system that is boost operated. basically there's a T pipe (and screamer pipe) just before the cat which has a actuator attached to a butterfly valve when you turn the boost up the actuator will open and you then have a straight through system.
LE53 (452BHp & 389ftlb's with Quaife) Wine red VIS FOOFY Audi RS4 B7
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Re: Would this work?
[Re: TurboNick]
#841014
30/05/2009 13:25
30/05/2009 13:25
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MattW
Unregistered
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MattW
Unregistered
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I think this is easier said than done it's all well and good just saying put a valve in the middle but then you have the problem with alot of back pressure. The car would need to be mapped with the valve on i'm not sure if it can be done on the standard Bosch ecu you'll have to wait for flea to comment. Also if it's done by the gas pedal and opens with the gas pedal I'd suspect you'll get alot more lag as at low rpm's the valve will be closed. If it was controlled by the throttle pedal then at low rpms as soon as you put your foot down it would be wide open, so there would be no extra lag. Mapping wouldnt even come into it, it wouldnt make a difference. You dont have to get it remapped if you swap the cat over!
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Re: Would this work?
[Re: Benny]
#841029
30/05/2009 14:14
30/05/2009 14:14
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MattW
Unregistered
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MattW
Unregistered
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Bet that's VERY loud, I'd still want it going through the back box!
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Re: Would this work?
[Re: ]
#841054
30/05/2009 15:21
30/05/2009 15:21
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MADCooP
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MADCooP
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Would using a butterfly valve on the front pipe not also have implications as far as the MOT's concerned? I would have thought so, seeing as the exhaust gasses are being diverted, this would give a false reading at the exhaust tip. Just seems like you would be leaving yourself a lot of work to do come mot time, if so.
Iain.
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Re: Would this work?
[Re: ]
#841056
30/05/2009 15:31
30/05/2009 15:31
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MattW
Unregistered
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MattW
Unregistered
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Depends which MOT station you go to I guess...
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Re: Would this work?
[Re: TurboNick]
#841272
31/05/2009 06:44
31/05/2009 06:44
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Bosco
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Bosco
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thats a neat bit of kit, and as its controlled by boost pressure ( i assume it s actuator is t eed into turbo actuator pipe )it could further be controlled by a solenoid valve so you could effectively have it working or not at the flick of a switch.... for mot time
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Re: Would this work?
[Re: ]
#841385
31/05/2009 14:17
31/05/2009 14:17
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MADCooP
Unregistered
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MADCooP
Unregistered
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it could further be controlled by a solenoid valve so you could effectively have it working or not at the flick of a switch.... for mot time Good idea Bosco, that could work. I still think I would be a touch worried about how loud this would be, and also the effects on the turbo, being that you would be running with virtually no back pressure. Would step gap rings be enough to aleviate this???
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