The sound difference in exhaust modes.

[ralph7]

Why is there only one valve per 2 pipes?

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[WD Pro]

Why is there only one valve per 2 pipes?

Our euro exhausts get delivered like this :

Which looks a bit shit if your one of those people that doesn't just look at the wheel, but you are tempted to look past the wheel :

So why it was off I took the opportunity to strip it and have it metallic ceramic coated - it should keep it looking good (especially compared to 'as supplied') and it should keep about 30% of the radiated heat away from the diff without having to wrap that area.

Anyhow, the descriptions on how the box works further up this thread are perfect, but I can add a bit more info when you reference these three photos.

Note the spot welds around the box :

They hold an internal baffle plate. splitting the box into two chambers.

I will call the first smaller chamber number 1 and the second larger chamber number 2.

Chamber 1 has a condensation drain.

Here is the non valve outer exhaust pipe internals :

That's the outer box wall you can see (remember our euros have a GPF so the internals are pretty mush as clean as the day they were made).

That pipe is perforated and runs through both chambers, pretty much up to the outer box wall.

Here is the valve inner / central exhaust pipe internals :

Note it was really hard to get a good photo down there as the valve took all the flash and the focus.

By naked eye, you can see straight down it, out of the back of the box and right to the first bend in the exhaust tubing.

Like the outer pipe it's perforated and as best as my eye can make out, I think the pipe has a small gap in it that vents into chamber 1 i.e. rather than one continuous pipe, it looks like two pipes perfectly in line, but slightly separated.

So ...

Valve open = Gas is straight though both chambers with some pipe perforations.

Valve closed = Gas backs up behind the valve. (depending on the box stuffing in chamber 2) a small proportion of the gas will pass through the perforations into chamber 2 and out of the perforations into the other tailpipe. Majority of the gas will pass through the pipe separation into chamber 1, head to the back of the box, to exit the other tailpipe passing some more perforations on the way.

Hope that helps - and saves @skinnyb from taking the sawzall to his exhaust ... lol

WD

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[ralph7]

Makes sense since the gas has to go somewhere if the valve is closed.
Through the perforations.

 

[AZ_Ryan]

Updated:

I ended up putting the factory resonator back on. The H-pipe drone around 3k was really getting me. I can tell a small difference in all modes now with track being the loudest. Thanks for all who replied.

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