Sport muffler not sporty--help me figure out why

[Jameel]

I bought a used example of this muffler (Dansk 92.511)from a fellow Pelican and put it on my brother's '79SC (stock CIS, early steel heat exchangers which we ceramic coated, smog pump delete, lines removed and plugged at heads)

https://www.pelicanparts.com/More_Info/10-1010-164-M350&SuperCat=Y&SVSVSI=5866.htm

It sounded so good that I immediately ordered an identical one for my '83SC (also stock CIS, but I'm running new Dansk SSI heat exchangers in the old , longhood style, just like on my bro's '79, but again, stainless and new Dansk product)

The '79 sounds just perfect. Deep growl at start, and that beautiful mix of throaty and raspy on throttle above 4000, but very tame and drone-free when highway cruising. It's the perfect mix.

But the same muffler on my '83 is basically no different than the stock-style Dansk 92.211 I had on when I rebuild the engine a couple years ago. It's pretty disappointing! I would love my car to sound like my brother's '79.

So two variables that I can think of that might *might* affect the sound.

1. His early steel heat exchangers being steel and not stainless
2. '79 3.0 has the big port heads.

I don't see how that should really affect the exhaust sound so drastically, but what do I know. Any thoughts from exhaust experts?

Here's a short clip of the '79. It's cut off a bit, but you get the idea. My car sounds nothing like this.

[David 23]

I'm anxious to follow this thread, as I have a lot of questions about current Dansk sport exhausts also.

[MStier]

I'm no exhaust expert, but it strikes me that the difference in materials could produce a significant difference in sound. I also wonder about the effect of the ceramic coating on the heat exchangers in the '79. You also mentioned the deletion of the smog pump in the '79, but I don't see where you've done that in the '83. The smog pump generates secondary combustion in the exhaust gases, and while I would intuitively think that would produce more sound, maybe it reduces it.

[175K911]

One other thought- the used one has been around long enough that the 'glass packing inside has been somewhat blown out thus reducing the muffler's ability to silence tones.

Easy way to tell would be to bolt your brother's muffler on your car and see how it sounds.

[Trackrash]

I think, as mentioned the only way to solve this mystery is to swap mufflers.

FWIW, I don't think these have any glass in them. The one on my car sounded perfect, as described, from day one and the tone has not changed noticeably in the 10 years I have had it.

[cmcfaul]

I had one of those 2 in, 1 out sport Dansk's on my 73 E with stock HE's. Sound was a little different over stock but nothing to write home about.

Chris
73 E

[Jameel]

Originally Posted by MStier

I'm no exhaust expert, but it strikes me that the difference in materials could produce a significant difference in sound. I also wonder about the effect of the ceramic coating on the heat exchangers in the '79. You also mentioned the deletion of the smog pump in the '79, but I don't see where you've done that in the '83. The smog pump generates secondary combustion in the exhaust gases, and while I would intuitively think that would produce more sound, maybe it reduces it.

'83 cars didn't have smog pumps. I thought about the ceramic coating a bit. It's pretty much just on the outside, so I'm thinking it probably has little effect on the sound.

Originally Posted by 175K911

One other thought- the used one has been around long enough that the 'glass packing inside has been somewhat blown out thus reducing the muffler's ability to silence tones.

Easy way to tell would be to bolt your brother's muffler on your car and see how it sounds.

The used one I bought didn't have that many miles on it, so that rules that out. Yeah, I should just put his on and see what it does.

[Jameel]

Originally Posted by Trackrash

I think, as mentioned the only way to solve this mystery is to swap mufflers.

FWIW, I don't think these have any glass in them. The one on my car sounded perfect, as described, from day one and the tone has not changed noticeably in the 10 years I have had it.

I think you're right. But it's going to be tough taking that muffler off big brother's 911. He loves that thing. Might have to do it while he's out of town.

[macssc911]

Jameel It’s Mac glad the 79 is sounding great, give yours some time to break in, trust me the one I sent you I broke it in, go work it man

[Jameel]

Originally Posted by macssc911

Jameel It’s Mac glad the 79 is sounding great, give yours some time to break in, trust me the one I sent you I broke it in, go work it man

Great to know! Just wish I didn't have to park it for the winter today. Something to look forward to in the spring. I took it on one last high rpm drive today to get the oil hot. The sound did seem to get a bit throatier.

[tobluforu]

Originally Posted by cmcfaul

I had one of those 2 in, 1 out sport Dansk's on my 73 E with stock HE's. Sound was a little different over stock but nothing to write home about.

Chris
73 E

Me too. I put one on my 72, boring. Got rid of it after a summer.
Hmmm, breaking in a muffler. I have heard of this before, but that I think only pertains to mufflers that have some form of packing. No amount of driving was going to 'break in" my Dansk sport.

[pampadori]

my exhaust setup got noticeably louder after a long dyno session where we had pretty much the whole system glowing red for about 20 minutes.

I bet you'd get more db's out of it if you beat the fire out of your car for a little bit. I mean, if you're looking for an excuse to do that!

[Trackrash]

One thing I noticed about my Dansk after I installed it. It didn't seem much louder than stock from inside the car. Maybe a little throatier as mentioned.

However a friend of mine told me he could hear me a block away with my new muffler. So how it sounds behind the car may be the key.

[Hi_Fi_Guy]

I pulled this bit of 70's nostalgia off the 1971 911T I rescued earlier this year. I thought it sounded horrendous but if it is loud you are looking for get yourself one of these. Probably sounded better when knew.

I picked-up the Dansk sport muffler and it is certainly much quieter and not as sporty as I had hoped for but after disturbing my neighbors and scarring small children with the racket made by the previous muffler the Dansk is orchestral by comparison.

[Trackrash]

I know this is going a little sideways, but. After a while I decided that I really wanted a TWO out muffler.

So, I went crazy with a hole saw on my new Dansk. Bought a stainless u bent 2,5" pipe and now have the muffler I always wanted. I did have to add a baffle in the right side, to calm it down some. It isn't too loud until I floor it at 4K rpm. It does drone. But I like the drone.
Here is a comparison of my muffler with a stock one.

[Jeff Higgins]

I've been through quite a few mufflers on my 3.0 MFI motor. Early Dansk single out sport, early Dansk dual out sport, early Leisritz dual out sport, three different M&K's, a Magnaflow crossover style, original 911R (basically megaphones straight through the can), a brand new Dansk single out sport, and now a brand new Dansk RSR style dual out.

All of the Dansks and the Leisritz have fiberglass packing in them. We had the Leisritz on my son's '68 912 with a '72 2.4 911 motor in it, freshly rebuilt, on the first startup. It cranked and cranked, undoubtedly filling the muffler with a bit of gas. When it fired, it farted a big flaming ball of packing down the driveway. Got a lot louder after that...

My new Dansks have all be significantly quieter than my older ones. My old single out now lives on my other son's '79 SC, and sounds absolutely glorious. It is actually as loud as my brand new RSR style dual out on my car. I'm convinced they burn the packing down over time and get louder.

Maybe you could speed the process on your new one. You know, take it off the car, pour some gas in it...

Just kidding. Kind of...

[Jameel]

Originally Posted by Jeff Higgins

I've been through quite a few mufflers on my 3.0 MFI motor. Early Dansk single out sport, early Dansk dual out sport, early Leisritz dual out sport, three different M&K's, a Magnaflow crossover style, original 911R (basically megaphones straight through the can), a brand new Dansk single out sport, and now a brand new Dansk RSR style dual out.

All of the Dansks and the Leisritz have fiberglass packing in them. We had the Leisritz on my son's '68 912 with a '72 2.4 911 motor in it, freshly rebuilt, on the first startup. It cranked and cranked, undoubtedly filling the muffler with a bit of gas. When it fired, it farted a big flaming ball of packing down the driveway. Got a lot louder after that...

My new Dansks have all be significantly quieter than my older ones. My old single out now lives on my other son's '79 SC, and sounds absolutely glorious. It is actually as loud as my brand new RSR style dual out on my car. I'm convinced they burn the packing down over time and get louder.

Maybe you could speed the process on your new one. You know, take it off the car, pour some gas in it...

Just kidding. Kind of...

Great response Jeff! I haven't really driven it hard since I put it on other than yesterday. It seemed to improve a bit even though it was pretty chilly out. Something to look forward to in the spring (or if we get a good rain and some more warmth before winter.)