thouths on a 997 GT3 muffler on smaller displacent air cooled motor?

[Ayles]

How did you attach to the factory muffler bracket?

[-Levi-]

Originally Posted by Ayles

How did you attach to the factory muffler bracket?

Built a bracket that bolts to the engine

[mikedsilva]

I see lots of references about using the GT3 muffler.. what about a stock 997 centre muffler. Would this be too loud and also restrictive?

[clutch-monkey]

no crossover there? interesting

[Ayles]

Originally Posted by -Levi-

Built a bracket that bolts to the engine

To the carrier? Do you have any photos?

Thanks!

[mikedsilva]

Originally Posted by Ayles

To the carrier? Do you have any photos?

Thanks!

I wouldnt mind seeing some too.
i just picked up a 997 Centre muffler, NOT GT3.. not sure if there is any value in fitting it up? It looks like it is going to be loud and also the tight 180 degree bends might be restrictive?
As much as I have tried to find, I haven't seen anyone's results from using a stock 997 centre muffler on an air cooled 911 yet...

[clutch-monkey]

The bends are radiused nicely I don’t see them being particularly restrictive?

[pdtweeks]

To the carrier? Do you have any photos?

here are pics of muffler carrier that I fabbed using original 964 carrier that came with my engine

[Mr. Merk]

Originally Posted by mikedsilva

I see lots of references about using the GT3 muffler.. what about a stock 997 centre muffler. Would this be too loud and also restrictive?

Jed Rogers down in Austin has a non-GT3 muffler on his 3.6 swapped Carrera. Can't remember if it was 997 or 991 but it looks and sounds awesome!

www.instagram.com/jedrogers

[jac1976]

Originally Posted by Mr. Merk

Jed Rogers down in Austin has a non-GT3 muffler on his 3.6 swapped Carrera. Can't remember if it was 997 or 991 but it looks and sounds awesome!

www.instagram.com/jedrogers

Now if Jed could just learn to drive...

[-Levi-]

Originally Posted by Ayles

To the carrier? Do you have any photos?

Thanks!

I will pop under the car this week and snap a few pics

[mikedsilva]

Originally Posted by Mr. Merk

Jed Rogers down in Austin has a non-GT3 muffler on his 3.6 swapped Carrera. Can't remember if it was 997 or 991 but it looks and sounds awesome!

www.instagram.com/jedrogers

From the photos, it's a 991 base centre muffler.

[Ayles]

Originally Posted by -Levi-

I will pop under the car this week and snap a few pics

Awesome! Thank you!

[jpnovak]

Yes, Jed has a 991 muffler and B&B long tube headers on the 3.6 swap. It also has a cam swap but otherwise stock 3.6 internals. Put down some strong numbers on the dyno. The car is dialed.

[-Levi-]

Originally Posted by -Levi-

I will pop under the car this week and snap a few pics

[jpnovak]

Nice bracket!

[mikedsilva]

Originally Posted by Bill Verburg

I understand that, that's why I suggested capping the the lower inlets, the upper will be more than sufficient and quieter.

I have questions...

[mikedsilva]

Originally Posted by Bill Verburg

You aren't going to hurt the torque curve. Pipes need to be sized proportionally to the expected flow, but a muffler servers a different purpose and works differently. For a muffler generally there is no such thing as too big, You'd probably want to just use the upper inlet and cap off the lower one

My motor is a 3.0 with the larger port heads, ITBs, 10.2 compression, webcams, Georges Euro headers.
I've just acquired a GT3 muffler.

Here are my questions:
- Being a 3.0 still, I imagine just the 'quiet' ports are all I need to use?
- on original GT3, what diam are the pipes leading into the muffler? 2 inch and 2.5 inch?
- on original GT3, does the car always run through the quiet pipes but then ONLY open the loud pipe when you hit the switch? Or did it open the loud pipes depending on vacuum and load?
- the collector on my headers is 2.0, and from what I can ascertain, the input diameter to the quiet port on the muffler is also 2.0.. so is it prudent to simply use 2.0 inch tubing from the header to the input of the quiet port? or is there any gain to using 2.25 and stepping down to 2 inch at either end?
- looking at pictures of the valve arrangements online, it appears that both the pipes that connect to the muffler, protrude quite a bit inside the muffler. Is that correct?

Cannot think of anything else to ask just yet.

[pdtweeks]

Originally Posted by mikedsilva

My motor is a 3.0 with the larger port heads, ITBs, 10.2 compression, webcams, Georges Euro headers.
I've just acquired a GT3 muffler.

Here are my questions:
- Being a 3.0 still, I imagine just the 'quiet' ports are all I need to use?
- on original GT3, what diam are the pipes leading into the muffler? 2 inch and 2.5 inch?
- on original GT3, does the car always run through the quiet pipes but then ONLY open the loud pipe when you hit the switch? Or did it open the loud pipes depending on vacuum and load?
- the collector on my headers is 2.0, and from what I can ascertain, the input diameter to the quiet port on the muffler is also 2.0.. so is it prudent to simply use 2.0 inch tubing from the header to the input of the quiet port? or is there any gain to using 2.25 and stepping down to 2 inch at either end?
- looking at pictures of the valve arrangements online, it appears that both the pipes that connect to the muffler, protrude quite a bit inside the muffler. Is that correct?

Cannot think of anything else to ask just yet.

Mike,
I can verify the that the inlet sizes on the GT3 muffler are 2" upper (quiet) & 2.5" lower (not-so-quiet). And they do protrude into the muffler a bit...the gaskets design requires this.
pd

[mikedsilva]

So a bit of an update.. I scored a GT3 muffler... and the first set of pipes I made were 2 inch.. My headers are from GT Racing.. 1 5/8 diameter. The collector is 2 inch. So, 2 inch from the collector to the quiet port with plates blocking the lower ports.
The sound level is very tame. And at WOT it has a great note, but still relatively friendly. The torque kicked in strong from below 3k (butt dyno only). Car ran great but perhaps it was my imagination, but the tacho needle didn't appear to move as fast in the upper rpm compared to down low.

I soon made some 2.5 inch pipes.. using a 2 to 2.5 reducer from the header, 2.5 inch pipe to the muffler.. protruding inside the muffler approx 1 inch. The exhaust note was not deafening. And was surprisingly still streetable. Butt dyno tells me that the torque down low is lost which makes it less fun on the street. Car has not been dynoed so I can not verify performance.

Not sure what my next step will be, if any.
Here is a quick sound clip using the 2.5 inch tubing.