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Old 04-27-2008, 03:57 PM   #1
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Default Open Dump tube or not?

Should I run an open dump tube or have it recirculated back into the exhaust? I haven't heard a miata with an open dump tube, but I think it would be much too loud for street use. Would adding a resonator of some sort help much? I have no fabrication or welding skills, so I will be taking it somewhere to have the work done. What should I do?
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Old 04-27-2008, 03:59 PM   #2
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I ran an open dump, it wasn't all that bad. Not bad enough that I cared. I do plan to recirc the WG with the new setup though just to keep things quiet.
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Old 04-27-2008, 04:27 PM   #3
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I plan to have the dump tube parallel the 3" exhaust to about the middle of the car, then dump back in. The further away from the turbo you dump it back in, the better. Here's the jist of it. The gases coming out of the turbo are hot and expanded. As they travel threw the exhaust, the cool down and slow down. Resistance in a pipe increases by the square of the velocity. Resistance in a pipe also decreases by 1/diameter^4. (has nothing to do with this discussion). Just tell whoever builds it to put the dump tube back into the 3" exhaust as late as far back as reasonably feasible.
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Old 04-27-2008, 04:59 PM   #4
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FYI Vibrant makes a WG dump muffler/flame supressor
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Old 04-27-2008, 05:42 PM   #5
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I think a lawnmower muffler is close to the same size as well, probably cheaper than the vibrant piece.
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Old 04-27-2008, 05:53 PM   #6
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i have a open dump on mine, i can't hear it open over the turbo and the straight open 3in exhuast, so it doesn't really matter IMO
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Old 04-27-2008, 07:28 PM   #7
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open dump sounds badass, keep it open.
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Old 04-27-2008, 08:07 PM   #8
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yeah I run open dump on my car now, and it sounds awesome IMHO, guys from the NE dyno day could tell you if they agree or not I'm sure
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Old 04-27-2008, 08:44 PM   #9
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i must have left before you ran. oh well
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Old 04-27-2008, 09:18 PM   #10
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Open dump tube here...it's not bad at all.


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Old 04-27-2008, 10:36 PM   #11
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Quote:
Originally Posted by airbrush1 View Post
yeah I run open dump on my car now, and it sounds awesome IMHO, guys from the NE dyno day could tell you if they agree or not I'm sure
it was awesome!!!!!


open dump FTMFW!!!!
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Old 04-27-2008, 10:52 PM   #12
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Use one of these:

http://store.summitracing.com/partde...5&autoview=sku

I plan to if I run a dump pipe at all.
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Old 04-27-2008, 10:57 PM   #13
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go with open sounds great. just is loud.
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Old 04-27-2008, 11:30 PM   #14
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Open
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Old 04-28-2008, 03:01 AM   #15
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You guys make it so simple to decide. Guess I'm going open and I'll see if I like it. Going open how far back should I run it?
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Old 04-28-2008, 03:44 AM   #16
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try to keep it away from any fuel lines/combustable areas.... sometimes those things shoot flames out
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Old 04-28-2008, 08:15 AM   #17
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Quote:
Originally Posted by JayMX5 View Post
You guys make it so simple to decide. Guess I'm going open and I'll see if I like it. Going open how far back should I run it?
just our of the enigne bay is enough, a turn down at the end would be nice too.
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Old 04-28-2008, 08:18 AM   #18
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Anyone have any good vids or sound clips of this on a Miata?
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Old 04-28-2008, 09:39 AM   #19
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i prefer to recirc myself, it just keeps the car cleaner underneath... i don't like exhaust on anything except the car behind me. it is also a bit more stealth sound wise... i don't feel the need to draw unnecassary attention from others (police included).
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Old 04-28-2008, 10:25 AM   #20
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If you do recirc, do as far back as you reasonably can, I recommend after cat.
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