Why just fix the leak when you can eliminate the choke points?

Discussion on fuel delivery & intake/exhaust tech & mods.
CapriceX2
Posts: 55
Joined: Sat Jun 22, 2019 3:06 pm

Why just fix the leak when you can eliminate the choke points?

Post by CapriceX2 » Wed Oct 07, 2020 7:07 pm

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.
CapriceX2
2011 Caprice 9C3 - TSP 220R W/ DOD delete, 10.8:1 compression, Stainless manifold back exhaust in progress
1995 Caprice Classic Wagon
1996 K2500 6.5L diesel

CapriceX2
Posts: 55
Joined: Sat Jun 22, 2019 3:06 pm

Re: Why just fix the leak when you can eliminate the choke points?

Post by CapriceX2 » Wed Oct 07, 2020 7:25 pm

Getting the old stuff dropped out of the way:
IMG_5128.JPG
IMG_5128.JPG (3.58 MiB) Viewed 860 times
The offending hole:
IMG_5129.JPG
IMG_5129.JPG (3.97 MiB) Viewed 860 times
CapriceX2
2011 Caprice 9C3 - TSP 220R W/ DOD delete, 10.8:1 compression, Stainless manifold back exhaust in progress
1995 Caprice Classic Wagon
1996 K2500 6.5L diesel

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storm9c1
Posts: 417
Joined: Wed Mar 27, 2013 11:47 pm
Location: Pittsburgh, PA

Re: Why just fix the leak when you can eliminate the choke points?

Post by storm9c1 » Thu Oct 08, 2020 2:03 am

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.
Tom (AKA: Storm)
2011 Caprice 9C3: L77, 8K miles, first-owner, purchased July 2011.
1995 Caprice 9C1: LT1, 178K miles, summer car.
1995 Impala SS: LT1, 21K miles.
1995 Caprice Wagon: LT1, 62K miles.
1995 Caprice Wagon: LT1, 128K miles. Rust In Pieces
1994 Caprice 9C1: LT1, beater winter car.
1969 Chevy C30: 383ci stroker, 4L80E, rollback car hauler.
1972 Chrysler Newport: 400ci big block, survivor 27K miles, 2-door hardtop.
1969 Dodge Charger: 383ci big block.

CapriceX2
Posts: 55
Joined: Sat Jun 22, 2019 3:06 pm

Re: Why just fix the leak when you can eliminate the choke points?

Post by CapriceX2 » Thu Oct 08, 2020 1:31 pm

storm9c1 wrote:
Thu Oct 08, 2020 2:03 am
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.
CapriceX2
2011 Caprice 9C3 - TSP 220R W/ DOD delete, 10.8:1 compression, Stainless manifold back exhaust in progress
1995 Caprice Classic Wagon
1996 K2500 6.5L diesel

CapriceX2
Posts: 55
Joined: Sat Jun 22, 2019 3:06 pm

Re: Why just fix the leak when you can eliminate the choke points?

Post by CapriceX2 » Thu Oct 08, 2020 1:47 pm

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.
IMG_5135.JPG
Sheet cut to size
IMG_5135.JPG (2.44 MiB) Viewed 830 times
IMG_5137.JPG
Home brew bending
IMG_5137.JPG (3.05 MiB) Viewed 830 times
IMG_5138.JPG
Top piece
IMG_5138.JPG (3 MiB) Viewed 830 times
IMG_5142.JPG
Test fit
IMG_5142.JPG (3.44 MiB) Viewed 830 times
IMG_5143.JPG
Loose assembly
IMG_5143.JPG (2.78 MiB) Viewed 830 times
CapriceX2
2011 Caprice 9C3 - TSP 220R W/ DOD delete, 10.8:1 compression, Stainless manifold back exhaust in progress
1995 Caprice Classic Wagon
1996 K2500 6.5L diesel

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storm9c1
Posts: 417
Joined: Wed Mar 27, 2013 11:47 pm
Location: Pittsburgh, PA

Re: Why just fix the leak when you can eliminate the choke points?

Post by storm9c1 » Thu Oct 08, 2020 3:11 pm

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?
Tom (AKA: Storm)
2011 Caprice 9C3: L77, 8K miles, first-owner, purchased July 2011.
1995 Caprice 9C1: LT1, 178K miles, summer car.
1995 Impala SS: LT1, 21K miles.
1995 Caprice Wagon: LT1, 62K miles.
1995 Caprice Wagon: LT1, 128K miles. Rust In Pieces
1994 Caprice 9C1: LT1, beater winter car.
1969 Chevy C30: 383ci stroker, 4L80E, rollback car hauler.
1972 Chrysler Newport: 400ci big block, survivor 27K miles, 2-door hardtop.
1969 Dodge Charger: 383ci big block.

CapriceX2
Posts: 55
Joined: Sat Jun 22, 2019 3:06 pm

Re: Why just fix the leak when you can eliminate the choke points?

Post by CapriceX2 » Thu Oct 08, 2020 4:47 pm

storm9c1 wrote:
Thu Oct 08, 2020 3:11 pm
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:
IMG_3415.jpg
IMG_3415.jpg (75.11 KiB) Viewed 815 times
CapriceX2
2011 Caprice 9C3 - TSP 220R W/ DOD delete, 10.8:1 compression, Stainless manifold back exhaust in progress
1995 Caprice Classic Wagon
1996 K2500 6.5L diesel

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storm9c1
Posts: 417
Joined: Wed Mar 27, 2013 11:47 pm
Location: Pittsburgh, PA

Re: Why just fix the leak when you can eliminate the choke points?

Post by storm9c1 » Thu Oct 08, 2020 8:57 pm

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.
Tom (AKA: Storm)
2011 Caprice 9C3: L77, 8K miles, first-owner, purchased July 2011.
1995 Caprice 9C1: LT1, 178K miles, summer car.
1995 Impala SS: LT1, 21K miles.
1995 Caprice Wagon: LT1, 62K miles.
1995 Caprice Wagon: LT1, 128K miles. Rust In Pieces
1994 Caprice 9C1: LT1, beater winter car.
1969 Chevy C30: 383ci stroker, 4L80E, rollback car hauler.
1972 Chrysler Newport: 400ci big block, survivor 27K miles, 2-door hardtop.
1969 Dodge Charger: 383ci big block.

CrashTestDummy
Posts: 2138
Joined: Sat Feb 07, 2015 8:31 pm
Location: Pearland, Texas

Re: Why just fix the leak when you can eliminate the choke points?

Post by CrashTestDummy » Thu Oct 08, 2020 9:55 pm

CapriceX2 wrote:
Wed Oct 07, 2020 7:25 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.
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2010 Tahoe PPV (her car)
1995 DGGM Impala SS
1996 BBB Impala SS (11-second DD)
1985 Firebird - 310 LS1 C Prepared autocross car.
And some others
Do YOU have my SPID?

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kevink
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Joined: Sun Aug 09, 2015 5:55 pm

Re: Why just fix the leak when you can eliminate the choke points?

Post by kevink » Thu Oct 08, 2020 10:08 pm

CapriceX2 wrote:
Thu Oct 08, 2020 4:47 pm

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".
2011 9C3: 11.48 @118.

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