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

Discussion on fuel delivery & intake/exhaust tech & mods.
CapriceX2
Posts: 85
Joined: Sat Jun 22, 2019 10:06 am

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

Post by CapriceX2 »

I cut the insulation for the other end and tacked the outer end plate in place. I guess you can’t really even see the end plates with the insulation bulging out.
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Then I cut a piece of the insulation that would wrap around the entire inner chamber. I laid it over the chamber and tacked on the top plate. Why can’t photos load consistently right side up?
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The side plates went on next.
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I just kept wrapping the insulation around as I added the plates. It is kind of ugly where it comes together on the bottom but oh well.
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After tacking all of the plates to the end plates this reminded me of the old saying about 10 lbs of stuff in a 5 lb bag.
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And this is where I stopped for the night. All of the seams are 100% welded except where the pipes pass through the outer end plates.
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It seems to be pretty acoustically dead. Wrapping on it with my knuckles just makes a thud.
CapriceX2
2011 Caprice 9C3 - TSP 220R W/ DOD delete, 10.8:1 Compression, Custom Stainless Exhaust
1995 Caprice Classic Wagon
1996 K2500 6.5L diesel
Turbopowered68
Posts: 141
Joined: Wed Nov 04, 2020 7:09 pm

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

Post by Turbopowered68 »

pleas put it on a scale before installation.
what do you figure? north of 30#s
2014 Caprice V8
Elgin E-1840 P, LS9 Head gasket, LS7 Lifters, PAC-1218 springs, Trunion upgrade, Single roller timing set, Melling oil pump, ZL1 torque converter, Camaro Trans pan and filter.
1986 GN
212/212 Roller cam, 1.65 HR Rockers, 60-1 turbo, XFI 2.05, E85, Ebay Front mount IC, Husek Built TH200-4R trans, 3.42 gears 3800# .
1968 Chevelle
LQ4, 4L80, 12 bolt w/3.42 gears
CapriceX2
Posts: 85
Joined: Sat Jun 22, 2019 10:06 am

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

Post by CapriceX2 »

Turbopowered68 wrote: Tue Jan 26, 2021 6:15 am pleas put it on a scale before installation.
what do you figure? north of 30#s
I should be able to check it this afternoon. I would guess it around 30 lbs. I'll also try weighing the factory parts that this replaces to get a comparison. I won't likely get that done today since it is buried in snow.

I finally loaded an idle walk around video of the first system. https://odysee.com/@TheMidwestHack:b/20 ... -Exhaust:1
CapriceX2
2011 Caprice 9C3 - TSP 220R W/ DOD delete, 10.8:1 Compression, Custom Stainless Exhaust
1995 Caprice Classic Wagon
1996 K2500 6.5L diesel
xcidmigs
Posts: 783
Joined: Fri Feb 13, 2015 8:12 pm
Location: SE PA

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

Post by xcidmigs »

What is the end goal here? silencing the now basically open exhaust? Is there a perforated tube inset inside this box? Or is it an X or H pipe inside? This seems like a again like what magnaflow and others have created already with the x pipe mufflers that have 2 in/2 out setups.
CapriceX2
Posts: 85
Joined: Sat Jun 22, 2019 10:06 am

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

Post by CapriceX2 »

Turbopowered68 wrote: Tue Jan 26, 2021 6:15 am pleas put it on a scale before installation.
what do you figure? north of 30#s
I checked it last week and it weighs in at a hefty 31 lbs. I still haven't weighed the factory parts to see how much things are changing. They are buried deeper in the snow now.
xcidmigs wrote: Fri Jan 29, 2021 4:06 pm What is the end goal here? silencing the now basically open exhaust? Is there a perforated tube inset inside this box? Or is it an X or H pipe inside? This seems like a again like what magnaflow and others have created already with the x pipe mufflers that have 2 in/2 out setups.
The photos I posted on January 21st show the inside of the chamber. There is nothing in it except a couple of braces.
  • It is not an X or an H.
  • There is no perforated tube.
  • It is not a muffler and is not intended to quiet anything.
It IS an expansion chamber - It is a significant change in the cross sectional area of the 3" pipes that will reflect a negative pressure wave back to the cylinder head. For more information on expansion chambers check out this superchevy article. http://www.superchevy.com/how-to/exhaust/0505phr-exh/

There is a lot of information in that article so I'll give you a couple bullets points that I found most interesting:
  • Header primary length is not very important. Anything between 24 and 36" will work just fine. Note that this also means putting effort into equal length primaries is not a good use of your time.
  • Size the primary pipe diameter to the exhaust port flow of the head.
  • Secondary length is much more important than primary. The secondary length must be terminated with a significant change in cross sectional area like dumping the headers to atmosphere or (in my case) an expansion chamber. Simply reducing it down to meet up with the rest of your exhaust is likely going to leave significant power on the table.
  • Secondary diameter should be about 1.75 times primary diameter.
  • After the expansion chamber, what you do with the exhaust is largely irrelevant as long as it can flow enough to meet your HP. A 500 HP engine needs exhaust that can flow 1100CFM total, or 550CFM per side. It doesn't matter if you have pipes, bends, resonators, mufflers, or a dump... as long as everything can flow 550 CFM it will not be a restriction. You can have the power of open headers yet maintain a relatively quiet setup
My setup has a lot of compromises. FIrst, I don't even have headers (yet). My primary length with manifolds is nearly non-existent. Second, my secondary length is really long. I had measured it at one point and I don't remember exactly what I found. I think it was around 4'. I'm ok with that since eventually I will probably put headers on and the secondaries will get cut to a more appropriate length.

NOW... A progress update:
I spent almost the entire day Saturday in the shop and got the system welded up and installed. Sunday we drove it about 3 hours round trip. The system fits up well. I do hear a "ting" once in a while on some of the bigger bumps on back roads, but nothing that annoys me too much. I will eventually go looking for the source, but I'm not in a hurry.
I think it sounds amazing at idle, low speeds, and WOT. I couldn't ask for anything better. I took my wife through an indoor drive-thru COVID testing facility and having a conversation with the staff with the engine running was a complete non-issue. The staff did not look annoyed at all and more importantly my wife was not annoyed.
At highway speeds around 65 or 70 there is a hum. Tone wise, it is basically a very quiet drone. It is quiet enough that I did not get any complaints from my wife on the 3 hour trip. It is quiet enough that you can still hear the tire noise and the wind noise. Hearing the radio is no problem. So it is really not bad and I'm OK with it.
I haven't taken any video yet, but will try to get that done and posted.
CapriceX2
2011 Caprice 9C3 - TSP 220R W/ DOD delete, 10.8:1 Compression, Custom Stainless Exhaust
1995 Caprice Classic Wagon
1996 K2500 6.5L diesel
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