matt33

Here we are again.. in search of the perfect exhaust sound.

Have any of you heard the difference (or can speculate?) on the sound difference between a standard swans neck vs the "extra long" swans neck pictured below?

Quieter/louder?
More/fewer pops/crackles when lifting?
Raspier/smoother?
High/low rev difference?

Related question.. have any of you tried the cargraphic sports muffler that replaces the secondary muffler? Is it closer in sound to a g-pipe/swans neck, or closer to the stock secondary muffler?

If the stock secondary muffler sound is a 1 and a g-pipe 10 in volume, I am looking for something that is a 7-8. Take the edge off a little.. but not much more. I need to keep the 100 cell sports cat.. so no option to go with a turbo-back solution.

Matty

Metal Guru

Maybe somewhat quieter as the swans neck get longer but all are going to be obnoxiously loud, IMO, except for the suitcase muffler.
I don't know if there are better options than the stock suitcase muffler or the replicas of it that are available since you have to keep your cat.
I use a Rarlyl8 muffler but I had to make a tailpiece for it. It's loud enough to sound good but it won't be so loud that I couldn't
stand to take a trip in my car.

cobalt

I replaced the entire system from turbo out. I have a magnaflow 3" in 3" out and it sounds quite nice. Lots of pops on liftoff and not too obnoxious under WOT. I did gut my WG muffler so it screams under WOT.

The swans neck is slightly quieter since you can't do what i have. You can cut slits into the swans neck and install baffles to help quiet it down if it is too loud. Although I tried the 100cell cat and swans neck and as great as it sounded it was still way too loud.

Another option is to cut open your stock muffler and weld a solid pipe in place. Dansk makes one like this already. The stock muffler dumps the exhaust into the housing and has a perforated pipe to allow the gases to exhaust out.

Metal Guru

Anthony, have you done this?
I'd guess there might be serious backpressure concerns with this mod.

cobalt

Yes early on. I still have the 100 cell cat I customized to fit and I am using the swans neck on my C2. I added the baffles which helped but not enough. No impact on performance.

You need some back pressure with turbo cars. This is far less restrictive but it was a 96 to 100 db car and brought far too much attention for a street ride. Sounded fantastic and I loved the sound of the turbo spooling down but had to go another route. I really like the magnaflow setup. It is just the right amount of sound for these cars but then there is the cat problem.

matt33

Without fabricating parts.. I think there are 2 options:

1. 200 cell sports cat + standard swans neck (I am assuming a 200 cell cat is somewhat quieter than a 100 cell due to additional surface materials/etc?)

or

2. Keep the 100 cell cat and swap the swans neck for the cargraphic sport muffler pictured above (which I am assuming is significantly louder than a stock secondary muffler)

Labor of love...

Matty

cobalt

You might inquire to how the sport muffler is made. If it is like the Dansk sport muffler it might not be any quieter than a swans neck. As I noted above the sport muffler does not use the chamber to flow the gasses through. It is possible that the housing around the pipe will quiet the sound but I have no idea if that is the case.

Metal Guru

I'm going to respectfully dispute this statement.

All parasitic losses like backpressure are bad for performance, no matter where they occur.

The ideal situation is to have the maximum mass flow through the engine to maximize efficiency but there will always be some losses; no system is perfect.
The turbine is already acting as an semi-effective plug in the exhaust system.

Backpressure will slow the exhaust gasses from exiting the exducer, thereby slowing down spooling time and also impeding exhaust gases from exiting the engine upstream; kind of a double whammy.

cobalt

Yes and no as far as I was told. I am running straight pipes right off my twin turbo track engine. Sounds great as the turbos spool up and down. However as it was explained to me lack of a small amount of back pressure will result in shorter turbo life. When I sourced my engine used it came with two sets of turbos for just this reason.

So as far as all out performance you are correct but if it helps longevity for a street car I would research this to be sure what I was told is correct. No doubt there is always trade offs with these kind of modifications.

Also wanted to add that many things including the turbo create back pressure where in the system can make a difference.

Metal Guru

The low-backpressure-at-the turbo myth just won't die.

I've done search after search and cannot find one coherent engineering reason why this would be so.

I would bet that turbos fail in track cars due to the extreme thermal input that high speed running does to the whole engine. Watch an engine dyno run with the turbine housing glowing and think of doing that to it lap after lap.

As a aside, I recommend putting a couple of engine breather filters on the wastegate breathers in place of those soda straws.

https://www.summitracing.com/parts/sbf-26-1330-01

I run two and they and spare me having to disassemble and clean dirt out of my wastegates every year.

cobalt

That was an early picture before it was done but I do have a long list of things that need to be done yet. It is still in shake down configuration.

Sadly I rushed the build to get some seat time and as usual life got in the way. I only have 3 events on it. It is just sitting off to the side for the last 8 months looking sad. Hopefully I can get it on my lift in another week or two but I have a 90 targa that belongs to my friend that won't leave. LOL First is to get the ignition switch replaced it keeps dropping the power to the brake pump. Nothing like coming into a turn at 140 and discovering you have no boost.

thanks for the link

Metal Guru

I don't recall seeing any pictures of the finished product.
What track is closest to you?
I hear ya about working on other people's cars.
My son acquired a one owner '93 Lincoln Mk VIII last weekend to be his plaything until he graduates in December. It's an interesting car in that it has the 4 cam Cobra V-8 in it, independent rear suspension and speed sensitive ride height control; kind of a hot rod Lincoln. So I can't resist the urge to color sand and polish it when I should be tearing into my car

cobalt

My wife and I and now my son travel to most east coast tracks. Closest are NJMP lightning and thunderbolt south & Lime Rock, Monticello north but my favorites are Watkins glen and VIR. I plan to drive as many tracks on the east as I can.

I don't have any current shots but here is my wife getting ready to go out at the glen and the concours setup. Since I didn't have time to drive it I showed it at Zone 1 and took first in race car class.

The last few events were done in the Boxster which is a fun car to drive but isn't quite the same.

Metal Guru

That's a pretty fancy track car. Very nice.

cobalt

These were very nice rides. I worked on one for an employee years ago. A lot of engineering although if the air pillows go it can be quite expensive to repair.

I don't seem to be able to do any project without making it nicer than its intended purpose. Must be the OCD side coming out. The car is a beast makes the 3.6T seem like a C2 in comparison. It will be nice when I finish all the little things. I also have a bunch of suspension changes I want to do. I picked up some Tarrett drop links and outer tie rods so I can lower it a bit more. I also will change the front suspension from the inner mount points to the outer to get more width in the front end. Running 9.5 fronts is a bit tough no matter what I do the tires do rub the front shields on partial lock makes a K turn quite difficult. But on track you never turn the wheel to that extreme. Once i get the suspension dialed in I think it can take on just about anything. I have no issue pulling on 991GT3's in a straight line just need to learn not to use the brakes so much. The 993RS brakes are far more aggressive than the stock turbo brakes.