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My 3" custom exhaust with spring loaded flapper valve

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Old Sep 22, 2015 | 12:26 PM
  #81  
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add splitter box, attach to regular throttle cable

...oh wait...
Old Sep 22, 2015 | 01:44 PM
  #82  
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What's the advantage of a complicated setup vs a simple spring?
Old Sep 22, 2015 | 02:08 PM
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Originally Posted by JasonC SBB
What's the advantage of a complicated setup vs a simple spring?
Never use one part when three will do! Use a vacuum motor!

--Ian
Old Sep 22, 2015 | 02:39 PM
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Originally Posted by JasonC SBB
What's the advantage of a complicated setup vs a simple spring?
Biggest thing that sold me on the one I got was the completely bolt-in install. No cutting/welding/etc.

Also it shouldn't cost even a single hp in backpressrue, since it doesn't use exhaust pressure to open.

I would also have "settleed" for a vacuum operated setup, except the quality ones are absurdly overpriced, and most of them are cutouts, which is not what I'm looking for.

I'll post results after it comes in.
Old Sep 23, 2015 | 10:27 AM
  #85  
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Originally Posted by 18psi
Also it shouldn't cost even a single hp in backpressrue, since it doesn't use exhaust pressure to open.
Have you seen my actual measurements? IIRC it was 0.3 psi. And that's with the stiffer of 2 springs.
Old Sep 23, 2015 | 07:23 PM
  #86  
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Ya know, back when I was a boy the muscle cars had vacuum operated valves on the mufflers to open them up when the throttle was opened.

Old Sep 23, 2015 | 07:38 PM
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They still do on "boring" cars...
Old Sep 23, 2015 | 08:34 PM
  #88  
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That doesn't work quite as well on boosted cars
And actually a whole lot of these "boring" cars use electric motors, and they fail quite often

Originally Posted by JasonC SBB
Have you seen my actual measurements? IIRC it was 0.3 psi. And that's with the stiffer of 2 springs.
Yup. And again, this is much easier cause I don't have to hack up my $1300 exhaust to put it on.
Old Sep 23, 2015 | 08:37 PM
  #89  
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my dad's bimmers all had wastegates on their exhausts.
Old Sep 23, 2015 | 09:31 PM
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Originally Posted by 18psi
That doesn't work quite as well on boosted cars
That's what vacuum reservoirs and check valves are for, same as on an NA car.

--Ian
Old Sep 24, 2015 | 07:51 AM
  #91  
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this is from a 330i:







oh but it don;t work on boosted cars he says....



takes a look at the 335i exhaust:






#boringcarsmatter
Old Sep 24, 2015 | 11:21 AM
  #92  
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Lol @ "vacuum reservoirs" on a Subaru/miata custom exhaust system
Old Sep 24, 2015 | 11:35 AM
  #93  
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ever seen a VICS IM?
Old Sep 24, 2015 | 12:19 PM
  #94  
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What is the fascination with vacuum and overcomplicating the everliving crap out of things?

oh that's right you're a mercedes driver now
Old Sep 24, 2015 | 12:28 PM
  #95  
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My B6 S4 had vacuum-operated exhaust flappers. They were ECU-controlled with solenoids, and the reservoir for them was buried in the trunk somewhere. It eventually started leaking so I disconnected them and that left the flappers open all the time, which was still substantially quieter than the Miata.

I'm pretty sure the C7 S6 has the same system, but I haven't needed to go looking for it.

Vacuum actuators are actually a decent solution for this kind of occasional thing, because they're simple, powerful, cheap, and have minimal moving parts.

--Ian
Old Sep 24, 2015 | 12:33 PM
  #96  
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More simple and less moving parts than the valve I ordered?

lol

You all know I've liked that whole idea for a long time now, in fact I've made a few threads about it along the way.

Scottiac made sure to derail each of them

(but seriously, I like vacuum activated flappers. just not gonna happen this time)
Old Sep 24, 2015 | 12:38 PM
  #97  
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Originally Posted by 18psi
More simple and less moving parts than the valve I ordered?
If you're a German OEM, needing to meet German idle noise laws, but still want your car to make good power and sound fast at WOT (and fake out the emissions test!), a passive spring-actuated flapper isn't gonna cut it.

--Ian
Old Sep 24, 2015 | 12:40 PM
  #98  
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Why not?
I didn't get the spring flapper, but the manual valve, but now I'm curious why you think that. The mitsu evo and many others do this very successfully
Old Sep 24, 2015 | 12:48 PM
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Originally Posted by 18psi

What is the fascination with vacuum and overcomplicating the everliving crap out of things?

oh that's right you're a mercedes driver now

im driving a 2015 c300 right now, wanna talk about over complicating? it took me a few minutes to get it out of park.
Old Sep 24, 2015 | 12:54 PM
  #100  
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exactly my point



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