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#631968 - 11/04/04 09:21 AM What's a downpipe on exhaust systems and what does it do?
oilpan49 Offline


Registered: 11/29/02
Posts: 926
Loc: Ohio
Ok when your talking about performance exhaust systems, what exactly is a downpipe and it's purpose?? I hear alot of people say that downpipes are the best thing for a good sound?? Thanks,,,,,,AR

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#631969 - 11/04/04 10:27 AM Re: What's a downpipe on exhaust systems and what does it do?
Anonymous
Unregistered


Downpipe is the short peice that goes from the exhaust manifold to the cat.

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#631970 - 11/04/04 05:02 PM Re: What's a downpipe on exhaust systems and what does it do?
Matt_S Offline


Registered: 12/02/03
Posts: 3094
Loc: Metro Detroit
ZmOz is correct, but to visualize it better, picture a transverse V6 arrangement. After the exhaust leaves the front manifold, it has to be piped over the transmission, where it joins with the rear manifold, then goes "down" to the converter. Longitudinal setups, like your truck, AR, won't be configured quite the same way. In that case, after the manifold, one side comes across to meet the other, then it goes straight back into the converter. It's not really called a downpipe. On cars that have them, people replace the downpipe with pipes that are either larger (a good idea IF you're producing enough HP to need it) or one with less restrictive bends. For racing/off road only applications, there are companies that sell downpipes that'll eliminate the converter. You can get an O2 spoofing module to prevent a CEL.

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#631971 - 11/04/04 06:12 PM Re: What's a downpipe on exhaust systems and what does it do?
oilpan49 Offline


Registered: 11/29/02
Posts: 926
Loc: Ohio
Thanks guys for the clarification. I was looking on the grandprixracing forum and there was a thread about exhaust setups and alot of the members there have downpipes on there GP's

Would anyone here have a sound clip of there vehicle with a downpipe on there?? Also where can you buy spoofed 02 sensors?? I read also on the GP forum that all you have to do is take the resistor out of the 02 sensor and that makes it spoof the PCM, am I correctly understanding this??? Thanks again,,,,AR

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#631972 - 11/04/04 09:13 PM Re: What's a downpipe on exhaust systems and what does it do?
Matt_S Offline


Registered: 12/02/03
Posts: 3094
Loc: Metro Detroit
A downpipe won't change the sound, at least not significantly. Headers, resonators (or lack thereof) and mufflers have much more of an impact on that.

I haven't heard of the homemade O2 spoof before. It sounds iffy to me, though. This is an example of an O2 simulator, but to cover my butt, I'll state clearly that it's not street legal to use this for the purpose of bypassing the converter. It would be acceptable for racing, though.

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#631973 - 11/05/04 12:41 AM Re: What's a downpipe on exhaust systems and what does it do?
oilpan49 Offline


Registered: 11/29/02
Posts: 926
Loc: Ohio
Thanks Matt for the link. I'll have to do some more research to find out more about these things,,,,,,AR

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#631974 - 11/10/04 06:35 AM Re: What's a downpipe on exhaust systems and what does it do?
Drew99GT Offline


Registered: 10/11/02
Posts: 21101
Loc: Colorado Springs
When people refer to a downpipe, they're usually referring to a turbocharged engine. The Downpipe is the pipe that comes of the exhaust housing of the turbo and conects to the cat usually. Some turbo cars hae an 02 sensor housing in between the exhaust housing of the turbo and the downpipe. I have never heard anyone refer to a naturally aspirated engine as havinf a downpipe. Headpipe/midpipe/catback yes! [I dont know]

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#631975 - 11/10/04 07:10 AM Re: What's a downpipe on exhaust systems and what does it do?
kenw Offline


Registered: 10/10/04
Posts: 1979
Loc: Houston
" have never heard anyone refer to a naturally aspirated engine as havinf a downpipe."

well, it's the very common name for the part of the exhaust pipe as described earlier.....the sevice receipt from Toyota on my 93 says: "replaced downpipe hanger bracket"

definitely not a turbo'd car.....

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#631976 - 11/10/04 09:38 PM Re: What's a downpipe on exhaust systems and what does it do?
JeepZJ4.0 Offline


Registered: 04/28/03
Posts: 1397
Loc: Katy, Texas
I call it a downpipe. More commonly called a Y-pipe. But since my Jeep only has one header... it's a downpipe.

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