What's inside 2018 GT mufflers?

[3star2nr]

Also, re power. Having a "restriction" at the end of the exhaust system is better than near the engine... The headers are where you make the bulk of hp due to the scavenging effect. And your collector design is what separates the good stuff from,the junk.

Just eyeballing it with no test data i highly doubt you will lose a bunch of power running the factory mufflers because they are actually pretty well designed... You'll also see marginal improvements in scavenging running a free flowing system as after the collectors the exhaust gases cool and start losing a ton of energy... So as long as the pipe isnt blocked off pretty much all your scavenging advantages are gone...

That's why running 2.5 vs 3in really doesnt impact power all that much.

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[Zinc03svt]

Actually it is more the pipes leaving the resonator going into the mufflers around the pumpkin/axles that pinch down to 2-2.25” crush bent that are not great for flow. I posted pics next to my flowmaster 3” mandrel bent ones. Big difference imo...

Plus most axle backs are just the mufflers and leave the stock pipes for the most part.

 

[3star2nr]

Actually it is more the pipes leaving the resonator going into the mufflers around the pumpkin/axles that pinch down to 2.25 crush bent that are not great for flow. I posted pics next to my flowmaster 3” mandrel bent ones. Big difference imo...

Plus most axle backs are just the mufflers and leave the stock pipes for the most part.

Yeah thats A ton of restriction close to the motor. I suspect ford did that prioriterizing packaging over outright performance.

Larger pipes will give you more "bark" and some people want that. I think you can think of exhaust as having similar science to a gun, larger calibre are typically louder as well (ignoring powder difference)

 

[jmeiers]

Well if you like them so much, mine are at the bottom of the Loudoun County landfill. They also sound like shit.

 

[jpogi]

From looking at the cutouts...

https://www.mustang6g.com/forums/threads/stock-resonator-cutaway.120726/



Looks like the resonator acts more like a perforated straight thru muffler, with glassfiber and wire mesh packing (first chamber is clear of packing that provides a crossover point).

While the actual pair of mufflers, are more like hemholtz resonators than "mufflers".

 

[ZeroTX]

From looking at the cutouts...

https://www.mustang6g.com/forums/threads/stock-resonator-cutaway.120726/



Looks like the resonator acts more like a perforated straight thru muffler, with glassfiber and wire mesh packing (first chamber is clear of packing that provides a crossover point).

While the actual pair of mufflers, are more like hemholtz resonators than "mufflers".

I found this thread while looking for info on what the inside of the mufflers on my non-active GT exhaust look like. So yeah, after adding a Steeda H-pipe, I'm gonna say that the "resonator" we are removing is actually the MUFFLER on these cars and that what's mounted behind the axle are RESONATORS, not mufflers. There's almost no sound suppression coming from those, just a change in sound at lower RPMs.

 

[Vlad Soare]

I'm gonna say that the "resonator" we are removing is actually the MUFFLER on these cars and that what's mounted behind the axle are RESONATORS, not mufflers. There's almost no sound suppression coming from those, just a change in sound at lower RPMs.

And yet the active valves in the mufflers do affect the sound level, and quite strongly at that. So at least some degree of sound suppression must happen in the mufflers as well.
Besides, a resonator delete increases the noise level just by a few decibels (about five, apparently, if the H-pipe reviews on YouTube are anything to go by), whereas removing the mufflers altogether and replacing them with straight pipes would probably make the car audible from the outer space.

 

[Mattpitcher]

I have a question for those that know about a later car WITH active exhaust. When the car is in RACE, is this basically making the rear mufflers a "straight Thru"? or would there still be more noise to be had by removing the rear mufflers all together and adding straight pipes and tips? I have active exhaust and and H Pipe and I have set the valves to RACE and unplugged them so its in race mode all the time, in regards to the exhaust valves at least. But its still too quiet for me, I'm thinking about doing a muffler delete but there's no point if the valves being open is already a straight pipe is there?

 

[crzystang]

I have a question for those that know about a later car WITH active exhaust. When the car is in RACE, is this basically making the rear mufflers a "straight Thru"? or would there still be more noise to be had by removing the rear mufflers all together and adding straight pipes and tips? I have active exhaust and and H Pipe and I have set the valves to RACE and unplugged them so its in race mode all the time, in regards to the exhaust valves at least. But its still too quiet for me, I'm thinking about doing a muffler delete but there's no point if the valves being open is already a straight pipe is there?

If it is still to quiet add LT headers!

 

[Ardiyanto]

Just wondering if anyone has been curious enough to cut open a 2018 non-active GT muffler to see what the construction inside is like? Straight through, baffled, holes for resonator effect, etc.

I know this thread is old, but I am dropping this picture as a reference here. It appeared to confirm that the stock Active Exhaust muffler a straight through design with perforations to direct the gas to the muffling part of the second tips.

Source: My screenshot of a Youtube Video by Crossplane Nation

 

[WD Pro]

Check out this post :

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

From this thread :

https://www.mustang6g.com/forums/threads/how-does-the-active-exhaust-work.181432/page-2#post-3658833

WD

Edit to add this info on the resonator :

I haven't run the CFD or tested it, but the differences shown here are larger than just run to run or day to day variation. The primary source of restriction change is the muffler, as the resonator is completely straight through.
https://www.mustang6g.com/forums/th...type-catback-on-2018-gt-massive-gains.123363/

Dyno's say the resonator is the restriction?

No they dont, the resonators are straight through like others said, these muffler designs are clearly horrible. How could you consider that a good free flowing design?

The resonator is straight through, but it does add a restriction - I’m not sure how much difference it makes in reality though :

Standard GT resonator does a similar thing :

• Standard pipe diameter = 2.5"
• Diameter at front manifold clamps = 2.25" (same for standard resonator and resonator deletes).
• Diameter at resonator outlet joint = 2.00" (removed with resonator delete).

WD

WD

 

[Ardiyanto]

Thank you for the details, WD. Were you able to tell if they have fibre /stainless wool/mesh around both pipes?

 

[WD Pro]

Thank you for the details, WD. Were you able to tell if they have fibre /stainless wool/mesh around both pipes?

I’m not sure to be honest and I’m not cutting mine up to find out …

This photo of a resonator would suggest that at least one of the compartments is glass packed :

WD

 

[jpogi]

Thank you for the details, WD. Were you able to tell if they have fibre /stainless wool/mesh around both pipes?

There is a youtube video of a kid cutting this open.

There are fibers and wool mesh in the two big chambers. But the small chamber does not have any, probably because both pipes are perforated and needed pressure to crossover for accoustics.

 

[Earlsays]

I put a Roush H pipe on my 2021 GT - there was drone, and it was just too loud for my poorly aged ears. I wound up purchasing a brand new OEM resonator to replace - when I put that back on the car, it was QUIETER than when my car was brand new. Over the next few weeks, the sound changed a bit, and it became just slightly louder, back on par with how it had been originally.

The photos of the packing / mesh within the stock resonator reinforces my theory that some of the packing burns off as time goes on, and it will get a bit louder.

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