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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
I sprayed 1 coat of regular flat black paint on the mufflers after the mod. you could smell it baking for about the first week. i checked them last night and the paint is still there, no issues thus far.
so it's a necessity that we have to paint the muffler when we're done? prevent oxidation?
You can use SS welding wire that will help prevent corrosion, but yes, it's a good idea to paint over the freshly exposed steel. Especially if using mild steel welding wire.
These are the pictures from someone who has done the muffler mod once. According to my experience, you will be doing it again, or will eventually throw away your mufflers and replace them with an expensive aftermarket system. The main reason is that the internal muffler baffles are only attached to the internal pipes by three tack welds on each pipe, and cracks will eventually emanate from the tack welds and cause your mufflers to emit a buzzing noise which will drive you crazy. Ask me how I know; I have been there already.
My mufflers have each been opened three times. Once for the mod, once looking for what is wrong, and the third time to fix the problem.
Cutting to the chase, the answer is to add weld material between the pipes and the internal baffles. Strive for a full fillet weld of as much of the circumference of each pipe that you can reach. Add gusset plates to this joint wherever possible. As best I know it, this will solve the problem. Mine has been fixed for about 18 months and counting.
So my recommendation is to make sure that yours is done like this the first time, because pulling those mufflers down the 2nd and third times is crazy.
Its not worth the effort. Only marginally louder. Better off just getting new mufflers or axel back exhaust.
Hirohawa,
I must respectfully disagree, with the X pipe mod and stock cats my car sounds super. In addition with the flip of a switch it becomes very quiet. I'll define your term "effort" as having to pay someone to do the work and that I can agree with. The only things I haven't done to my car is setup the diff and the machine work on the heads, other than that all the wrenching was done by me. Heads off and on, diff out and back in, they are really quite well built machines and fun to work on. My $0.02.
All of this goes away with the C8, my remark to the other Vette owner at the showing at a local Chevrolet dealer was, there is something to be said for having the title at home in the safe.
These are the pictures from someone who has done the muffler mod once. According to my experience, you will be doing it again, or will eventually throw away your mufflers and replace them with an expensive aftermarket system. The main reason is that the internal muffler baffles are only attached to the internal pipes by three tack welds on each pipe, and cracks will eventually emanate from the tack welds and cause your mufflers to emit a buzzing noise which will drive you crazy. Ask me how I know; I have been there already.
My mufflers have each been opened three times. Once for the mod, once looking for what is wrong, and the third time to fix the problem.
Cutting to the chase, the answer is to add weld material between the pipes and the internal baffles. Strive for a full fillet weld of as much of the circumference of each pipe that you can reach. Add gusset plates to this joint wherever possible. As best I know it, this will solve the problem. Mine has been fixed for about 18 months and counting.
So my recommendation is to make sure that yours is done like this the first time, because pulling those mufflers down the 2nd and third times is crazy.
I'm here now, in my garage, opening up the mufflers, mainly because there is a bad "buzzing" resonance coming from them which is annoying as hell ! So you'd ecommend welding everything to everything that can be ? Theres nothing obviously loose, but obviously running exhaust gas through them makes the difference. Did you get any pictures ? And did the exhaust valves still work, as it looks like the input pipe goes straight through (via the perforated pipe) straight out the exit pipe which has the butterfly valve on it .. a lot of questions, but like you say, do it once. Plus if it comes to new boxes they're not exactly off the shelf here in the UK. Thanks in advance J
I'm here now, in my garage, opening up the mufflers, mainly because there is a bad "buzzing" resonance coming from them which is annoying as hell ! So you'd ecommend welding everything to everything that can be ? Theres nothing obviously loose, but obviously running exhaust gas through them makes the difference. Did you get any pictures ? And did the exhaust valves still work, as it looks like the input pipe goes straight through (via the perforated pipe) straight out the exit pipe which has the butterfly valve on it .. a lot of questions, but like you say, do it once. Plus if it comes to new boxes they're not exactly off the shelf here in the UK. Thanks in advance J
I used the 2 stainless steel band clamps method with no internal welding (just welded the cans back shut) and no issues in over 10 years now. I think they were 3 or 4" wide each, just tighten them down good and tight. Grind off your welds and paint the cans with high temp spray paint (engine paint) to prevent rusting. They will probably rust from the inside eventually, nothing you can do about that, but no signs of coming through on mine.
While the welding pieces of pipe method may seem more permanent, it makes sense that there could be a rattle, you have 2 pieces of pipe touching each other that are only welded in certain places. There will always be the chance that something will vibrate. The band clamps are secured tightly to the entire pipe, nothing that can rattle. Also much easier to do and won't rust out.
Make sure you put the sound deadening/packing bags back in before closing them up as that can cause some resonance too.
You should leave the butterflies open all the time (pull the fuse) after making this mod. The restrictive pipes will still work but they will be more restrictive after this mod, possibly too restrictive.
You should leave the butterflies open all the time (pull the fuse) after making this mod. The restrictive pipes will still work but they will be more restrictive after this mod, possibly too restrictive.
Lo and behold, passenger muffler opened and the baffle has a hole shot in it and a crack almost the whole way round !!
I'm thinking I'll just repar this and shore up all the welds on both mufflers. I wasnt looking for more noise, just stopping the resonance one, and by the sound of it (no pun intended) I'll pretty much lose the quiet option if I close up the perforated pipe ? Which great at 70mph on long journeys.
I've got the mild2wild remote so can always have permanent loud anyway.
j
Lo and behold, passenger muffler opened and the baffle has a hole shot in it and a crack almost the whole way round !!
I'm thinking I'll just repar this and shore up all the welds on both mufflers. I wasnt looking for more noise, just stopping the resonance one, and by the sound of it (no pun intended) I'll pretty much lose the quiet option if I close up the perforated pipe ? Which great at 70mph on long journeys.
I've got the mild2wild remote so can always have permanent loud anyway.
j
Foxie,
You are on the right track. In my own experience and that of others, the welding of the internal pipes to the baffles is the problem. My thinking is that your cracking of the baffles is pretty advanced. So find the best welder you can and lay weld bead over all of the cracks and also over as much of the tube to baffle joints as possible. Also add gussets to these joints as possible. Put the fiberglass stuffing back in the mufflers before closure. When I did this, my car with OEM cast manifolds and gutted cats is not excessively loud. On the highway, there is no drone. And on track, I get lots of compliments about how great the car sounds. Surely, I could get 20 more hp with a set of long tube headers and a retune, but I am not interested in doing that. I run fast enough without 20 more hp.
Foxie,
You are on the right track. In my own experience and that of others, the welding of the internal pipes to the baffles is the problem. My thinking is that your cracking of the baffles is pretty advanced. So find the best welder you can and lay weld bead over all of the cracks and also over as much of the tube to baffle joints as possible. Also add gussets to these joints as possible. Put the fiberglass stuffing back in the mufflers before closure. When I did this, my car with OEM cast manifolds and gutted cats is not excessively loud. On the highway, there is no drone. And on track, I get lots of compliments about how great the car sounds. Surely, I could get 20 more hp with a set of long tube headers and a retune, but I am not interested in doing that. I run fast enough without 20 more hp.
On a tangent, did you manage to find/build O2 Simulators for your gutted cats or did you use the spacer method to remove the post-cat sensors from the path somewhat?
I removed the O2 sensors entirely first and then used a very long drill bit and a longer piece of rebar to remove the cat/core and stuffing. Then reinstall your cat pipes on the cast manifolds and hook up the 02s. Then, what I would do if I was doing it again is to start the engine. Just let it run about 15 seconds with the H or X pipes unhooked. This will blow the rest of the crap out. The bits that you could not drive out with the rebar, even though you think you have done a great job. Best to put an open box behind the pipe openings to keep from making a mess in your garage.
Since I did not know to do this, all of my crap got routed through my mufflers and blew out all over my garage anyway. One week later I drove my car on a 200+ mile trip for a dyno tune, and after I got home I found a large piece of cat core was stuck and partially blocking one of my bimodal muffler valves. I was able to fish it out with no harm done. I would rather not have blown all that crap through my mufflers though. Anyway, I hope my story helps you.
Originally Posted by foxie
Lo and behold, passenger muffler opened and the baffle has a hole shot in it and a crack almost the whole way round !!
I'm thinking I'll just repar this and shore up all the welds on both mufflers. I wasnt looking for more noise, just stopping the resonance one, and by the sound of it (no pun intended) I'll pretty much lose the quiet option if I close up the perforated pipe ? Which great at 70mph on long journeys.
I've got the mild2wild remote so can always have permanent loud anyway.
j
I removed the O2 sensors entirely first and then used a very long drill bit and a longer piece of rebar to remove the cat/core and stuffing. Then reinstall your cat pipes on the cast manifolds and hook up the 02s. Then, what I would do if I was doing it again is to start the engine. Just let it run about 15 seconds with the H or X pipes unhooked. This will blow the rest of the crap out. The bits that you could not drive out with the rebar, even though you think you have done a great job. Best to put an open box behind the pipe openings to keep from making a mess in your garage.
Since I did not know to do this, all of my crap got routed through my mufflers and blew out all over my garage anyway. One week later I drove my car on a 200+ mile trip for a dyno tune, and after I got home I found a large piece of cat core was stuck and partially blocking one of my bimodal muffler valves. I was able to fish it out with no harm done. I would rather not have blown all that crap through my mufflers though. Anyway, I hope my story helps you.
Originally Posted by foxie
Lo and behold, passenger muffler opened and the baffle has a hole shot in it and a crack almost the whole way round !!
I'm thinking I'll just repar this and shore up all the welds on both mufflers. I wasnt looking for more noise, just stopping the resonance one, and by the sound of it (no pun intended) I'll pretty much lose the quiet option if I close up the perforated pipe ? Which great at 70mph on long journeys.
I've got the mild2wild remote so can always have permanent loud anyway.
j
04-28-2010, 08:32 AM
