New Caprice - Discussion forums

I’ve been listening to an exhaust leak on this car for quite a while. It is annoying, but not obnoxious so it has been easy to put off the repair. I’ll link a video of it idling for reference. I’m not sure what happened to the video sound, but it somehow picked up a bunch of extra noise. I finally got to a good stopping point on a truck project and decided it is time to give the PPV some love.

Turns out the hole is in the top of the first muffler. The shared one where the 2 sides come together. The cheapest option would be to cut it out and replace it with a couple pieces of pipe. I’ve already eliminated DOD, so the DOD drone would not be a concern if I were to go that route. But if I’m already under there hacking up the exhaust, why not eliminate some of the choke points while I’m at it?

My current plan is to build an expansion chamber to go in place of the failed muffler. I’ve read several of Vizard’s articles on using expansion chambers to build a no-loss exhaust system and have been wanting to try it. This seems like an ideal platform to try it on since we have this great area where the pup cats and muffler currently reside. I’ll join the manifolds to the expansion chamber with 3” pipe. Yes, this is overkill with the 2 1/8” outlet of the manifolds, but I’m planning ahead for headers. Speaking of the manifolds, I also plan to do some massaging at the outlet to get them up to at least 2 ¼”. Out of the expansion chamber will be 2 ½” pipe back to the factory muffler flange. I’m going to leave the factory mufflers alone for now. My wife has already voiced significant concern over making this car sound like… umm… “poop”. Which, I think, means loud.

My intent is to eliminate the exhaust leak, eliminate the 3 major restrictions on each side, while also making the exhaust no louder than it is with the current exhaust leak.

I'll update here as I go.

[media]https://open.lbry.com/@TheMidwestHack:b ... 967ergcUDY[/media]

It doesn't look like the embedded video is going to work for me. Here is a link that should: [nturl]https://open.lbry.com/@TheMidwestHack:b ... 967ergcUDY[/nturl]

Well, I can't figure out how to embed it, but either link above should take you to the video.

Getting the old stuff dropped out of the way: The offending hole:

Side note... I was convinced that the PPV used better quality stainless steel on these exhaust components compared to the old B-Bodies, which do/did the same thing to their mufflers after several years! Interestingly, even in the most snowy, salty, rust belt climates, I've had stock mufflers rust out but not stock pipes on the B-Body cars. Seems the PPV is doing the same.

This isn't offering much advice except that maybe you can salvage the pipes. Less risk there.

I'd be tempted to delete that muffler and install an X-pipe instead in this case.

Keep us posted on your progress.

storm9c1 wrote: ↑Wed Oct 07, 2020 9:03 pm Side note... I was convinced that the PPV used better quality stainless steel on these exhaust components compared to the old B-Bodies, which do/did the same thing to their mufflers after several years! Interestingly, even in the most snowy, salty, rust belt climates, I've had stock mufflers rust out but not stock pipes on the B-Body cars. Seems the PPV is doing the same.

This isn't offering much advice except that maybe you can salvage the pipes. Less risk there.

I'd be tempted to delete that muffler and install an X-pipe instead in this case.

Keep us posted on your progress.

My '96 wagon got all new 2.5" stainless exhaust from the cats back. It didn't really need it at the time, but the mufflers were STARTING to fall apart. My current '95 wagon is a Florida car and the exhaust is holding up well. I have Borla mufflers and an assortment of 2.5" bends waiting to be installed in it, but my wife doesn't see the value in replacing a perfectly good exhaust.

At this point I'm not planning to keep anything between the manifold and the muffler flange... but plans can change.

I made a little progress on the expansion chamber last night:
- Started cutting some stainless sheet to size
- Bent it with a make shift bender
- Test fit it in the space available

Hoping to get it tacked together today.
I also placed and order from siliconintakes.com for the stainless pipe. This was the cheapest source I could find for 304 mandrel bends. If anyone knows of a cheaper source, please share. The ones I ordered are about $25 a bend for the 2' sections.

Nice! What gauge metal is that?

My exhaust guy just buys those "bend assortments" in bulk and just cuts/welds pieces to get the radius he needs. He said it's the cheapest method to get mandrel bent pipes. He feels that as long as the welds are clean, there are no concerns with flow due to the seams. Although he is more critical on the race exhausts he builds versus street. There are multiple sources for these sections. Is that what you ordered? Or did you actually have custom bends made?

storm9c1 wrote: ↑Thu Oct 08, 2020 10:11 am Nice! What gauge metal is that?

My exhaust guy just buys those "bend assortments" in bulk and just cuts/welds pieces to get the radius he needs. He said it's the cheapest method to get mandrel bent pipes. He feels that as long as the welds are clean, there are no concerns with flow due to the seams. Although he is more critical on the race exhausts he builds versus street. There are multiple sources for these sections. Is that what you ordered? Or did you actually have custom bends made?

The stainless measures about .050". So 18 gauge. Very tough to weld without burn through, even with 1/16" rod. It will be slow going to get this sealed up.

No custom bends. Just generic 90's and straights. I'll slice them up as needed. I've also just sectioned pipe before to make up what I need. Makes for a lot of welding. Here is a downpipe I made up a few years ago:

Yep, that's the ticket. Making bends from other sections. You definitely aren't messing around with dinky stuff going with 18 gauge. Each challenge is lesson.

Curious to see your progress on this... I'll be following. Keep up the good work.

CapriceX2 wrote: ↑Wed Oct 07, 2020 2:25 pm <SNIP>
The offending hole:
IMG_5129.JPG

Our '12 had that on the top of one of the rear mufflers where the seam is welded together. Another bad spot was the flex pipe at the front of each rear muffler mount. Had to cut a couple of the bolts there to drop the exhaust. Our car was a Wisonsin car, so it wasn't unexpected.

CapriceX2 wrote: ↑Thu Oct 08, 2020 11:47 am
The stainless measures about .050". So 18 gauge. Very tough to weld without burn through, even with 1/16" rod. It will be slow going to get this sealed up.

1/16" rod is your problem. Use 0.035".