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

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

Post by CapriceX2 » Thu Oct 08, 2020 10:34 pm

Welds weren’t too pretty but they ground down ok.
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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

lastcall190
Posts: 567
Joined: Mon Sep 11, 2017 10:17 am
Location: North Jersey

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

Post by lastcall190 » Fri Oct 09, 2020 12:16 am

I welded a couple times and the phrase I channeled was "A grinder and paint make me the welder i ain't"

I think it looks good along with the downpipe. Reminds me of the homemade intercooler pipes on my previous vehicles, good times.

My center section muffler looked the same (rusted and separated) and my axle back muffler had a hole in it. Cats and rest of the pipes were fine, strangely enough

-J
2012 Caprice
2008 CVPI

Both gone but not forgotten...

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 » Fri Oct 09, 2020 12:25 pm

kevink wrote:
Thu Oct 08, 2020 10:08 pm
1/16" rod is your problem. Use 0.035".
I haven't found smaller than 1/16" rod for SMAW (stick welding). It isn't too bad. Took some effort to get the current set just right, I can only make short stitches, and the arc blow is unreal at times; but with the right technique it isn't going too bad.

At 0.035", I assume your are talking TIG rod? I've just barely scratched the surface with TIG. I suppose I should put some effort into learning it, but I'll do that on some mild steel scrap. I'm too cheap to learn on stainless!
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

Fandango
Posts: 20
Joined: Fri Jun 12, 2020 5:31 am

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

Post by Fandango » Fri Oct 09, 2020 9:37 pm

Cool.

I wonder about those flat sections vibrating from the exhaust pulses and causing some noise. I think that's why most exhaust stuff is oval/round. Either way, looking forward to the progress.

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 » Sat Oct 10, 2020 1:45 pm

Fandango wrote:
Fri Oct 09, 2020 9:37 pm
Cool.

I wonder about those flat sections vibrating from the exhaust pulses and causing some noise. I think that's why most exhaust stuff is oval/round. Either way, looking forward to the progress.
Yeah, I have the same concerns.

Even without the end plates installed, I can stand on it. Does that mean it is strong/stiff enough to not vibrate with exhaust pulses? No idea.

I got one end plate cut out last night. I’ll get it cleaned up and add some photos in a bit.
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 » Sat Oct 10, 2020 3:42 pm

Look what showed up a couple days early!
Guess I won’t run out of things to do this weekend. Like that ever happens.
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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 » Sat Oct 10, 2020 11:21 pm

The first end plate is welded to the expansion chamber. Pulled out the old exhaust.

And the project grows...
Both mufflers are also shot. Seams are splitting and rust has opened them up.
I’ve got a set of Borla ProXS on hand that were supposed to go on the wagon. Guess I’ll try them here.
Guess the exhaust just got louder.
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Attachments
258C6C5B-4649-44DF-AAC6-71E5E3E81378.jpeg
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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 » Sun Oct 11, 2020 2:07 pm

The outlet of the exhaust manifolds have a step down to about 2 1/8. I started smoothing this out before my compressor died last night. I’ll need to swap compressors around before I can finish the blending.
Here’s how it looked when the compressor died:
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And here is where it started:
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I have the other end of the expansion chamber cut out and tacked in. No photos yet.
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

User avatar
storm9c1
Posts: 418
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 » Mon Oct 12, 2020 4:20 pm

Interesting restriction there. Almost looks intentional and not a casting flaw. I wonder if that was engineered into the manifolds to either increase velocity or create some turbulence before entering the cats.

Just guessing, but I'm wondering if the AFM (or other part-throttle condition) was causing some popping in the manifolds and keeping the velocity up would smooth it.

FWIW, unsure if this applies here, but properly engineered restrictions in an exhaust system can have a significant bearing on gas velocity. Which can also lower unwanted noises. For example, it's reasonable to have a larger pipe at the manifolds, then gently reduce to the cats, then smaller pipes after the mufflers, with the theory being that as the gasses cool, they no longer need the same larger diameter to maintain the same velocity. Keeping the velocity up as the gasses cool helps with scavenging, but perhaps more importantly, helps with unwanted noise, drone, etc. With low velocity, big pipes become echo chambers.

I'm not an exhaust engineer, so this is all just spit balling as far as I'm concerned. Although I do work for a software company that produces software to simulate just about anything in engineering... including the flow of gasses and liquids through pipes, and some of the simulations are pretty neat.
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 » Mon Oct 12, 2020 6:57 pm

storm9c1 wrote:
Mon Oct 12, 2020 4:20 pm
Interesting restriction there. Almost looks intentional and not a casting flaw. I wonder if that was engineered into the manifolds to either increase velocity or create some turbulence before entering the cats.

Just guessing, but I'm wondering if the AFM (or other part-throttle condition) was causing some popping in the manifolds and keeping the velocity up would smooth it.

FWIW, unsure if this applies here, but properly engineered restrictions in an exhaust system can have a significant bearing on gas velocity. Which can also lower unwanted noises. For example, it's reasonable to have a larger pipe at the manifolds, then gently reduce to the cats, then smaller pipes after the mufflers, with the theory being that as the gasses cool, they no longer need the same larger diameter to maintain the same velocity. Keeping the velocity up as the gasses cool helps with scavenging, but perhaps more importantly, helps with unwanted noise, drone, etc. With low velocity, big pipes become echo chambers.

I'm not an exhaust engineer, so this is all just spit balling as far as I'm concerned. Although I do work for a software company that produces software to simulate just about anything in engineering... including the flow of gasses and liquids through pipes, and some of the simulations are pretty neat.
My guess is that this step is intended for an exhaust donut. Our application doesn't use one, but these manifolds are used in other places. Wondering if they designed the manifold to be able to seal in different ways depending on application.

Here is a photo of a spare manifold for my truck. Looks very similar to me.
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Here is the donut and how it fits into that recess.
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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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