991 muffler on and earlier aircooled motor

[mikedsilva]

I've seen some examples of people using the GT3 mufflers on aircooled cars.
But not seen any examples of stock 997 or stock 991 mufflers being used on aircooled cars. I have come across a 997 and a 991 muffler, but not sure what is inside them.

Has anyone here used a standard 997/991 muffler on their car? Or do you know what is inside the 991 muffler?

The 991 muffler is a lot larger but still just fits under the rear bumper.




Am I wasting time pursuing this?

[faapgar]

Easy install by shortening the exhaust entrance pipes a few inches and then you have a straight shot to the header.Then remember Porsche designed it and it should flow pretty well.Use V-Clamps and voila leak free.Fred

[pampadori]

what is the top one from in the first picture?

[Cook&Dunning]

The top muffler looks like a stock 997 Eberspacher. Not my engine in this pic, but this has been done.

[jpnovak]

Yes. Both 997 and 991 mufflers work well. Invert your shorty header adapters. a couple 90 elbow bends mitered to fit and you are done.

The other option is a wide header like the B&B.

Quieter than a sport muffler at idle. flows well and opens up at WOT to a good sound.

[Andy Somogyi]

Nice work!

Does this muffler have an internal collector, I.e. a tow into one?

Wonder how it would work on a 4 cylinder 912?


Sent from my iPhone using Tapatalk Pro

[jpnovak]

The 997 center muffler is two independent paths.

I think this would be complete overkill for a 912

[pampadori]

these don't have the actuator diverter valve thingies on them. Is that only on GT3?

[mikedsilva]

Originally Posted by pampadori

what is the top one from in the first picture?

hi
top one is from a 997.

[mikedsilva]

Originally Posted by pampadori

these don't have the actuator diverter valve thingies on them. Is that only on GT3?

yeah, that's only on the GT3..

[mikedsilva]

I believe that this photo (not of my muffler) is the internals of the 997. It seems not a lot of baffling and that the resonator chamber is quite small.. would it have been packed with any material or is it just the chamber?

[mikedsilva]

Originally Posted by jpnovak

Yes. Both 997 and 991 mufflers work well. Invert your shorty header adapters. a couple 90 elbow bends mitered to fit and you are done.

The other option is a wide header like the B&B.

Quieter than a sport muffler at idle. flows well and opens up at WOT to a good sound.

Jamie
have you seen or heard this fitted? I am concerned that they may be too loud as there appears to be zero baffling or muffler packing and the pipe is virtually straight through.
I have uploaded what I believe is a picture of the 997 internally, but I have not been able to find a pic of a 991 internals..
My motor is a lightly modified 3.0 Carrera .. higher compression and more aggressive cams with ITBs and efi. It flows a lot more than a stock motor.
Am I better to try to get the 991 muffler installed instead of the 997 due to the extra volume of the muffler, which should help to quieten it down? Interestingly, the 'outlets' on the 997 are 2.25inch.. and on the 991, they are only 2 inch. Not sure what to make of that...

[jpnovak]

Just put one on a 3.6 recently. Attached to B&B headers.

I think it is quieter than my 2.2 with a sport muffler.

BTW, there is another design (different manufacturer or maybe model year) where the 180 bend in the middle is actually a chamber and not a tube. This is visible using a flashlight. I am not sure if there is any additional muffler packing in that design.

[JeremyD]

Originally Posted by Cook&Dunning

The top muffler looks like a stock 997 Eberspacher. Not my engine in this pic, but this has been done.

Hey, that's my old 3.6

it actually ended up coming out great and sounding great.

No drone - sounded like a 911.

https://www.youtube.com/watch?v=cG8vI0Njm6Y

[mikedsilva]

Originally Posted by JeremyD

Hey, that's my old 3.6

it actually ended up coming out great and sounding great.

No drone - sounded like a 911.

https://www.youtube.com/watch?v=cG8vI0Njm6Y

hi Jeremy, thanks for posting.
It does sound good in the video.. was it 'loud'? Sometimes it is difficult to really pick up the feeling of how loud something is on screen. My M&K GT3 muffler makes my ears hurt!

[JeremyD]

Sound is so subjective - I can tell you that I also had a GT3 MK version - and it was louder than this.

Would you want to talk on the phone in an G series car with this muffler - probably not - but you really don't want to anyway - one of the reasons that I have a 996TT - it did sound great though

[GH85Carrera]

OK, I have to ask, WHY?

From the reports I have read the stock muffler against almost any other muffler is at most 5 to 8 HP. I presume that muffler is a lot louder than stock, and has no heat exchangers, so no heat in the car. I guess if you live in southern Florida, or Cali, no heat is not a big deal.

I am NOT saying don't do it, or complaining, it is your car, do whatever modifications you want or that make you happy. It for sure is something easy to change back.

I drive my 911 on long road trips, in the winter and even in the rain. I have driven it in 0F degree temps, and 118 temps in 42 states. I can't imagine not have a good heater and air conditioning in my 911.

What driving do you do in your loud no heat 911? Honest question.

[mikedsilva]

hi Glen
fair question. I'm a fair weather driver. I have other cars for rain, cold, weather.. this is a 'fun' car for me. I also enjoy building, modifying, testing etc.
Regarding heat, I live in Queensland, Australia.. it never really gets cold enough to warrant a heater. Also, this is a hobby car for me so I only drive when it suits me and whilst aircon would be nice, my car didn't come with it and I have no plans to cool it anyway. (summer is hot and sticky here, so not a lot of driving)

My engine is modified slightly and stock mufflers simply do not flow enough air for me to realise the engines full potential. Yes, it has been measured on the dyno several times with several different mufflers.. I have a thread elsewhwere on here tracking my successes and failures with dyno charts to prove.

So I am on the quest to find a muffler that
1 - does not hinder performance
2- sounds good (to me)
3 - looks good
in that order of importance.

I have seen many references to people using the GT3 muffler on the aircooled cars. The GT3 muffler doesn't have much of a restriction inside.. so I thought, since these mufflers are thousands, how about a 997 or 991 muffler from a stock car, that only costs a couple hundred.
It's an experiment, if anything. Also, we all have different perceptions of what is loud, sounds good, etc and some people say the 997 muffler is way too loud and droney, others say it sounded great and was not overly loud. I guess by posting this thread, I was hoping to narrow down to which one I should try first, if either... it seems I am not wasting my time, as there have been more positive responses than negative.

But like anything, the only way to find out is to perhaps do it myself.

Mike

[mikedsilva]

Originally Posted by JeremyD

Sound is so subjective - I can tell you that I also had a GT3 MK version - and it was louder than this.

Would you want to talk on the phone in an G series car with this muffler - probably not - but you really don't want to anyway - one of the reasons that I have a 996TT - it did sound great though

Ok, sounds encouraging. If the M&K was louder, then this is heading in the right direction.

[GH85Carrera]

Originally Posted by mikedsilva

hi Glen
fair question. I'm a fair weather driver. I have other cars for rain, cold, weather.. this is a 'fun' car for me. I also enjoy building, modifying, testing etc.
Regarding heat, I live in Queensland, Australia.. it never really gets cold enough to warrant a heater. Also, this is a hobby car for me so I only drive when it suits me and whilst aircon would be nice, my car didn't come with it and I have no plans to cool it anyway. (summer is hot and sticky here, so not a lot of driving)

My engine is modified slightly and stock mufflers simply do not flow enough air for me to realise the engines full potential. Yes, it has been measured on the dyno several times with several different mufflers.. I have a thread elsewhwere on here tracking my successes and failures with dyno charts to prove.

So I am on the quest to find a muffler that
1 - does not hinder performance
2- sounds good (to me)
3 - looks good
in that order of importance.

I have seen many references to people using the GT3 muffler on the aircooled cars. The GT3 muffler doesn't have much of a restriction inside.. so I thought, since these mufflers are thousands, how about a 997 or 991 muffler from a stock car, that only costs a couple hundred.
It's an experiment, if anything. Also, we all have different perceptions of what is loud, sounds good, etc and some people say the 997 muffler is way too loud and droney, others say it sounded great and was not overly loud. I guess by posting this thread, I was hoping to narrow down to which one I should try first, if either... it seems I am not wasting my time, as there have been more positive responses than negative.

But like anything, the only way to find out is to perhaps do it myself.

Mike

OK, fair enough. The main thing is make it what YOU want.

A recently rode with a friend of mine that has a 2011 911 Cabriolet Turbo. It has stock exhaust and the exhaust is nice and quiet in normal driving. He had a chance to "open it up" for two short bursts, and that thing is LOUD as far as I was concerned. It was silly fast of course, but pretty loud. Personally too loud for my tastes, but it ain't my car.

I have had my 1985 911 for almost 24 years, and there is almost nothing I have not worked on to make it as good as it can be, or even better than stock. It is just my vision of a 911. I will be driving it from Oklahoma City, to Key West Florida this summer. That is almost 1,700 miles each way, and summer in Florida is gonna be HOT!. I plan to stay cool with the AC in my car.