bspvette

I have an AutoX only C4, with an LS6. I am always looking for ways to lose weight, so this winter I would like to find a way to lighten my exhaust.

I'm currently running the Melrose LS headers, connected to 2.5" pipes, through an "X" pipe, and then to 2 three chamber Flowmasters at the back. Most places I run limit exhaust noise to 98db at 50', and my current system is typically right at the limit.

A few guys have suggested switching to either 2 or 4 glasspack style mufflers, and then exit in front of the rear wheels, or place turndowns right below the differential. I like this idea because it would remove the muffler weight all the way at the back of the car, but I'm not sure if these mufflers would quiet the car enough.

Have any of you experimented with a setup like this? Any suggestions?

Thanks,
BeerMan

sperkins

You want the weight at the back of the car. Heck, I have some offbrand mufflers that I run at times because they're heavy as lead. I would focus on removing weight from the nose, or at least further forward than the mufflers.
Just my $0.02

joenationwide

You could remake as much of your exhaust out of aluminum, and then V-band it to the 2.5" steel pipes. A friend did that on his car, worked well. He made his own aluminum mufflers too with some perforated tube, and wrapped thin sheets around to create the outer skin, and stuffed in some packing to quiet the sound.

bspvette

This is a good point. I have pretty good balance right now after losing almost 1000lb from stock. Most of the exhaust weight seems to be from the mufflers, so it seems that moving them forward would reduce the amount of weight swinging around at the back end of the car (I forget the term for that at the moment). But I realize that this would effectively move the weight balance forward a little bit. It seems like this would be a good trade-off, yes? No?

I guess my thought is that moving as much weight as possible from the nose and tail, to between the axles would be a good thing. I'm open to opinions/experience on this.

BeerMan

bspvette

Wow, that seems like a lot of trouble to go through when there are probably some commercially available parts to do the same thing. But even if I did go through that much trouble, I still wouldn't know whether it was below the legal 98db limit until I was finished.

I'm looking for someone who has tried different combinations, and knows how little straight through muffler length I can get away with & not **** off the sound meter guy.

BeerMan

Solofast

Seriously bad idea. At the exhaust gas temperatures a track car sees aluminum has all the stiffness of taffy on a hot day.... Could work for a drag car if you are only on it for 10 seconds, more or less, but on a road course you'll melt an aluminum exhaust in no time.

If you want to save some weight you can use titanium, or go to a higher strength nickel alloy and use thinner material, but aluminum isn't going to work for a long time on the track...

TrackAttack

Some people have used the Burns Stainless mufflers with success on a few different generations of corvettes. They are known to be pretty darn light and have a few options for sound level. they arent cheap but they make some nice stuff http://www.burnsstainless.com/
(you can tell whats been on my Christmas list lol)

The aluminum tubing just isn't worth the weight vs. possibility to fail when you consider how little more 18gauge stainless weighs in my opinion. Plus the weight of the added vband and flanges probably outweighs the small weight gain of aluminum. The mufflers on the other hand are a great place to pull out weight.

How does you car sit now? full interior/ac/radio/stock seats? fully stripped and caged?


Also with turn downs, it really blows dust all over the place when just driving around which is annoying

Tuned in for others answers

geerookie

Correct but you want the bias towards the rear. 48% / 52% would be nice. Keep the weight between the axles.

bspvette

But if I'm at 51/49 right now, is it worth going to 52/48 or 53/47 in order to move weight between the axles?

bspvette

Dang, that car sounds great. I could listen to that all day. But I bet it would be way over my 98db limit at full song. I'll check out the Burns stuff to see if they have something a little more .... uh.... controlled.

My car is fully stripped, with a 4-point bar. It has been lightened in about every way imaginable without going to any CF. The only things I haven't addressed are the exhaust, and the 700R4 tranny. I know I'll be able to get a bunch of weight out by going to a light weight manual (I really only need 2 gears for AutoX), but don't want to assume there's nothing to gain in the exhaust.

I know I could buy a whole bunch of different muffler combinations, and then test to see which one is the lightest without being too loud. But that would be way beyond my budget. I need to make an educated guess that will get me in the ballpark on the first try.

I just wish there was some kind of simulation software available, kind of like the Comp Cams Desktop Dyno, that would allow you to select all of your components, and then predict what your sound type & volume would be.

BeerMan

sperkins

No.

69427

I disagree. I welded up an aluminum muffler of my own design to both reduce the system weight and to move it to a different location for a reduction of moment of inertia. I ran it for a season of track days behind my 427 with no problems. At WOT and high power levels the car is moving fast enough to get plenty of cooling air across the reasonably large surface area of a higher capacity muffler.

Got no problem with titanium, although it's a bigger PITA to cut, drill or form.

waddisme

During tracking season I run the Borla straight pipes - 12lbs vs 50lbs for my Bassanis. Tolerable for dd, but just barely.

Not sure if this is below the 98 decibels though:

rfn026

Sell your house and buy an Inconel system. Everyone in F1 uses it and a lot of the Sprint Cup guys do as well. It comes in 0.020 wall thickness. The big problem is if you grip it too tightly during installation it'll bend. Some teams have stopped using it because they were destroying so many during installation.

If you want to get rid of weight you have to get serious. OK, it might be easier to just go on a diet. I know it'll be cheaper.

Richard Newton
Car Tech Stuff

bspvette

If I had the money for an Inconel system, I would just buy a whole bunch of different systems & test them to see which ones meet the sound meter requirements.