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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 02-14-2012, 10:16 PM   #21
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Quote:
Originally Posted by Rennkafer View Post
If you've ever heard a Gallardo start up and wondered why it has a huge bark on startup but then it's not too loud right thereafter, this is why... they have just exactly what you're describing. One just upstream of each muffler. I had to wire them closed on a customers car because he was shipping it to Taiwan and it wouldn't pass their sound regs with it open at startup.
Reading around and thinking off the top of my head, there are actually quite a big of high end cars that have these things. Vettes have em, lambos have em, and a bunch of other cars.
If it works on a 200k exotic, I dont see why it wouldnt' work on a miata.
I know they probably have theirs made of unobtanium and all that, but I dont see why a few hours worth of welding/fab couldn't produce a solid boost activated cutout.
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Originally Posted by chriscar View Post
Here's a DIY jobbie from SR20forum.com
http://bit.ly/ACxYet


This is GREAT
A little too ghetto-rigged for my taste, but id be interested in making my own as well.
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Why would a dump be quiet?
Why would it not if you're staying out of boost?
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Old 02-14-2012, 10:34 PM   #22
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my car is reasonably quiet til that 38mm dump opens. it would be quieter if i could fit something bigger than a cherry bomb in that tiny exhaust channel under my car.
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Old 02-14-2012, 11:10 PM   #23
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That's what im saying a large muffler is still a must and wont flow any less than a small one.
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Old 02-14-2012, 11:57 PM   #24
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Why is a muffler a must?
If using this as a dump I'd drive around on stock exhaust, and open up to 3" free flow only past 5psi or whatever I'd set it to.
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Old 02-14-2012, 11:58 PM   #25
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Old 02-14-2012, 11:59 PM   #26
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Old 02-15-2012, 12:00 AM   #27
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Old 02-15-2012, 12:01 AM   #28
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Old 02-15-2012, 12:02 AM   #29
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Old 02-15-2012, 12:03 AM   #30
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Old 02-15-2012, 12:04 AM   #31
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i have a few wastegate actuators and some exhaust layin around
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Old 02-15-2012, 12:13 AM   #32
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Those look like they work damn good to me. Go for it and post videos!
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Old 02-15-2012, 01:06 AM   #33
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Originally Posted by Savington View Post
And then when you're done driving, you can swap them for your hearing aids so you can hear the bingo numbers being called out.
Huh? Didn't quite catch that, sonny.
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Old 02-15-2012, 02:00 AM   #34
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Well

My quick spool valve quiets tge car down A LOT when it is closed
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Old 02-15-2012, 02:04 AM   #35
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Me and Justin (fastivab6t) will probably start working on a homemade version of a SP boost cutout sometime soon.

So far I see no downside to this.
If anyone brings up a valid point, I'm all ears.
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Old 02-15-2012, 02:17 AM   #36
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I just don't see the point in doing it. The majority of the benefit of having a free-flowing exhaust is to improve spool, so just having a cutout open in boost defeats the purpose completely, and if you're going to design an exhaust that's free-flowing enough to still spool well while still being quiet around town, then why would you bother with the cutout at all?
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Old 02-15-2012, 03:47 AM   #37
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i figure i big open dump wastegate does the same thing but it gives me something to build...
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Old 02-15-2012, 09:03 AM   #38
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Quote:
Originally Posted by 18psi View Post
Me and Justin (fastivab6t) will probably start working on a homemade version of a SP boost cutout sometime soon.

So far I see no downside to this.
If anyone brings up a valid point, I'm all ears.
The hardest part would be making the valve seal while closed. My limited experience with commercially available electronic valves with halfway decent tolerances/seal still *tick*tick*tick with exhaust leaks. Using an old junk throttle body may help but that's just ghetto.
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Old 02-15-2012, 09:42 AM   #39
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Ok, I think we are on the wrong page here, when you say this:

Quote:
Alright bros, so lets pretend for a second that a fellow was planning on building yet another turbo miata. Lets say he wanted as much of the 3" exhaust flow as possible, but with absolutely as little noise as possible.
I don't assume what you're really saying is this:

Quote:
Alright bros, so lets pretend for a second that a fellow was planning on building yet another turbo miata, but this time I want it to spool and perform absolutely horribly. I'd want it to have fairly good exhaust flow, as much of the 3" exhaust flow as possible, but only under certain conditions--after the turbo took 2000RPM longer to spool. Also, lets make sure it does this with absolutely as much noise as possible after that point.

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Old 02-15-2012, 10:57 AM   #40
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what about this ---> http://www.dynomax.com/mufflers.php?muffler=vt

MotoIQ seemed to like it on one of their project cars.

I was thinking of trying one out on my forester xt...
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