Miata Turbo Forum - Boost cars, acquire cats.

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-   DIY Turbo Discussion (https://www.miataturbo.net/diy-turbo-discussion-14/)
-   -   My 3" custom exhaust with spring loaded flapper valve (https://www.miataturbo.net/diy-turbo-discussion-14/my-3-custom-exhaust-spring-loaded-flapper-valve-62488/)

Braineack 09-22-2015 12:26 PM

add splitter box, attach to regular throttle cable

...oh wait...

JasonC SBB 09-22-2015 01:44 PM

What's the advantage of a complicated setup vs a simple spring?

codrus 09-22-2015 02:08 PM


Originally Posted by JasonC SBB (Post 1268726)
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

18psi 09-22-2015 02:39 PM


Originally Posted by JasonC SBB (Post 1268726)
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.

JasonC SBB 09-23-2015 10:27 AM


Originally Posted by 18psi (Post 1268749)
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.

sixshooter 09-23-2015 07:23 PM

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.

http://creativefan.com/files/2010/08...-3-500x335.jpg

Braineack 09-23-2015 07:38 PM

They still do on "boring" cars...

18psi 09-23-2015 08:34 PM

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 (Post 1268984)
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.

Braineack 09-23-2015 08:37 PM

my dad's bimmers all had wastegates on their exhausts.

codrus 09-23-2015 09:31 PM


Originally Posted by 18psi (Post 1269239)
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

Braineack 09-24-2015 07:51 AM

this is from a 330i:

http://forum.e46fanatics.com/attachm...5&d=1039977824

http://forum.e46fanatics.com/attachm...hmentid=470288



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



takes a look at the 335i exhaust:

http://www.e90post.com/forums/attach...1&d=1289751135




#boringcarsmatter

18psi 09-24-2015 11:21 AM

Lol @ "vacuum reservoirs" on a Subaru/miata custom exhaust system

Braineack 09-24-2015 11:35 AM

ever seen a VICS IM?

18psi 09-24-2015 12:19 PM

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

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

codrus 09-24-2015 12:28 PM

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

18psi 09-24-2015 12:33 PM

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 :giggle:

(but seriously, I like vacuum activated flappers. just not gonna happen this time)

codrus 09-24-2015 12:38 PM


Originally Posted by 18psi (Post 1269380)
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

18psi 09-24-2015 12:40 PM

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

Braineack 09-24-2015 12:48 PM


Originally Posted by 18psi (Post 1269373)
:facepalm:
What is the fascination with vacuum and overcomplicating the everliving crap out of things?

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


im driving a 2015 c300 right now, wanna talk about over complicating? it took me a few minutes to get it out of park.

18psi 09-24-2015 12:54 PM

:laugh: exactly my point


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