Will a stock gt3 exhaust work with a 3.0 engine

[blackrado]

Hi there, i have a 1980 3.0 in a 1977 911s chassis. Id like a muffler with the GT3 outlet. Is there any issue running a stock gt3 muffler with the smaller 3.0 engine?
Downsides? upsides?

Just wondering if MK, Dansk are the only options or if i can look for a salvage one as well.

Thanks.

[Classic 911]

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[JackkTheMackk]

It will cost you $5,000 to do it properly, with no significant gains for a stock engine.

You will need headers, vacuum controlled valved intermediate pipes, a new rear valence and paint, muffler bracket, vacuum solenoid/wiring, and the cost of the muffler with tips/hardware/no broken studs.

My loud inlet has a valve that i rewired the passenger left/right power mirror switch to open/close the valve via a vacuum solenoid in the trunk that pulls vacuum from the intake. The exhaust will drone on the highway if i’m running both loud and quiet inlets but with only the quiet inlet there is no drone.

For an all out built engine, it’s worth it. For a stock one, not at all.

[speedster911]

I have a 997 GT3 muffler sitting on a shelf debating if I will use it - I was surprised how heavy it is. If i was looking for the "LOOK", I would go M&K for weight savings, ease of install and cost

[2.7RS]

https://youtu.be/O5aIs2QmbYA

[2.7RS]

https://youtu.be/rA6FWmLRv1k

[Geneman]

THis is great thread on putting a GT3 muffler on an air cooled pcar. The gentleman, Levi, was extremely helpful when i did my swap.

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

[acme911]

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

I put motorcycle baffles in mine. No drone. Makes a great sound. It’s in the link.

[RarlyL8]

We've done a bunch of these systems, on engines ranging in size from 2.7L to 4.0L and power levels ranging from 180hp to 400hp.
The positive aspects of this conversion are that the muffler has the capacity to support such a wide range of displacement and power plus it has a more quiet mode. The looks are nice and the weight isn't too bad. Huge plus if you are weight conscious and use the titanium muffler, they weigh in at an unreal 8 pounds.
The negative would have to be that they are custom systems which can get pricey. This is assuming you like the look of the huge GT3 tailpipes.
Installing on a 3.0L would give no performance benefit over typical headers and free flowing muffler but you do get the look and the dual mode action. Performance gains come once the displacement passes 3.2L or the anticipated power is greater than 250hp. At that point conventional headers and mufflers designed for stockish engines (up to 3.2L) become restrictive while this one is just getting started. They are great for big displacement high power engines, which is what they were designed for.

[Geneman]

What Brian said! My experience is on a full on dedicated race car. I was trying to tip-toe the line between reduced noise for quieter tracks, occasional neighborhood street used for tuning and good looks... not exactly sure what my end goals were other than to get rid of the megaphones. Turned out: i like the look/sound, but still too noisy for lime rock, and unanticipated that its quite heavy hanging off the rear ( would definitly do a titanium one instead but big $$ diff.) Hard to tell on performance as have not dynoed but demonstrable increase in mid range i guess due to back pressure compared to megs. motor is a highly tricked out 3.0 SS, twin plug, high comp. , 50mm PMO carbs, big cams made by Knightrace. Georges knockoff headers or SCARGO. vcannot remember. Car made 295 at wheels before i added the GT3 unit.
Note i routed only thru top inlet: no valve. The stock muffler hangar and straps from a 997 worked well with little mods required. I do have a blistering problem on the bumper paint from the heat. Fabspeed boys told me to use the stainless steel DEI insulation wrap/plate which i am installing now. Overall. very happy with outcome. I have a separate potential solution for noise abatement ( see post below) but its ugly as sin...

[Geneman]

This was my earlier solution. highly influenced by the laguna seca boys many of whom run them claim it can get to <105dB. or less with little power loss . The mufflers are custom made by a guy in bay area (name escapes me) . after much custom fab of the hangar and header flanges, once i got it assembled on car i pretty much hated it . I am going to test anyway at LRP with turn downs added to see if it passes.

[mikedsilva]

Originally Posted by blackrado

Hi there, i have a 1980 3.0 in a 1977 911s chassis. Id like a muffler with the GT3 outlet. Is there any issue running a stock gt3 muffler with the smaller 3.0 engine?
Downsides? upsides?

Just wondering if MK, Dansk are the only options or if i can look for a salvage one as well.

Thanks.

Which Muffler? Dynomax, Magnaflow, M&K - Dyno Charts

[blackrado]

Great info everyone! Thank you all for the thoughtful responses.


My 3.0 has small port, 9.3comp and the M1 cams, early style heat exchangers and otherwise stock. Probably not worth the effort or money at this point. I’ll look to the mk or Dansk for now.

[Carbster09]

I would suggest getting a system from RarlyL8. I had one with GT3 style outlets in Hooligan and it was the best money I ever spent on the car. The sound was just epic.