ZL1 Bimodal Exhaust

Discussion on fuel delivery & intake/exhaust tech & mods.
Pursuit
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ZL1 Bimodal Exhaust

Post by Pursuit » Tue Jan 10, 2017 6:09 pm

I started this mod back in June and I am still not done with it as far as making the valves work. The parts used were a complete cat-back Camaro ZL1 take off. Craigslist $250. I used a Jones exhaust X-pipe PN SXP4SS and two Vibrant merge collectors PN 10358. I did have a Camaro L99 cat back system on it with the Camaro LS3 manifolds and all four catalytic converters. The manifolds and cats stayed. I cut the factory ZL1 H-pipe out added the X-pipe and still had to add a couple of inches to compensate for the longer wheel base of the Caprice.
Attachments
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L99 Camaro exhaust with Solo Axle-backs and single turndown tips
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ZL1 exhaust laid out on floor
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ZL1 mufflers cut off
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Maurice Sheil

mhsheil@gmail.com

2011 Caprice Phantom Black 9C3
2012 Impala 9C1
1995 9C1 Caprice
1996 GMC Sierra C1500
1974 SJ Grand Prix 455 well optioned with factory moon roof

Pursuit
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Re: ZL1 Bimodal Exhaust

Post by Pursuit » Tue Jan 10, 2017 6:14 pm

I then started to dissect the mufflers to straighten out the two exit pipes. I used the merge collectors to go from two 2-1/2 outlets to 1 3" outlet. I added a single piece of stainless pipe and then cut it to match the curvature of the bumpper
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Maurice Sheil

mhsheil@gmail.com

2011 Caprice Phantom Black 9C3
2012 Impala 9C1
1995 9C1 Caprice
1996 GMC Sierra C1500
1974 SJ Grand Prix 455 well optioned with factory moon roof

Pursuit
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Joined: Tue Apr 23, 2013 8:39 pm
Location: Omaha, NE area

Re: ZL1 Bimodal Exhaust

Post by Pursuit » Tue Jan 10, 2017 6:19 pm

The welding was done by my friend Jeff Allen at J2 Speed. We got the mufflers and outlets centered in the openings and then welded new hangers and transition piping from the mufflers back to the original pipe near the IRS. We did keep the two bolt flanges in their factory locations. We left the Solo Axle back mufflers in place while we made the transition from the ZL1 piping to the two bolt flange. We then took the Solos off, bolted new flanges in place and welded the Bi-modal mufflers to that connection point. AND, yes, I screwed up and one of the valves is upside down! :o We will fix that later.
Car sounds really good with the valves "failed" in the open position. The vacuum lines and operation will be a Spring time addition. I have removed the valves and wired them closed. The car still sounds good, but the DoD drone is there. But not as bad as I had assumed. About the same as a Solo Axle back that has not been tuned.

Maurice
Attachments
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Maurice Sheil

mhsheil@gmail.com

2011 Caprice Phantom Black 9C3
2012 Impala 9C1
1995 9C1 Caprice
1996 GMC Sierra C1500
1974 SJ Grand Prix 455 well optioned with factory moon roof

xcidmigs
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Location: SE PA

Re: ZL1 Bimodal Exhaust

Post by xcidmigs » Tue Jan 10, 2017 11:56 pm

Always great to see someone try to work something up themselves instead of just buying off the shelf. Is there any difference on the ZL-1 pipe diameter to the OEM Camaro SS? I have the LS3 Camaro pipes on mine based of your original thread about how to do it I just combined them into the rear portion of the caprice pipes ahead of the bolt on flanges, definitely not ideal but over I'm happy with the sound, cost etc... I've been thinking lately about installing a pair of low profile electric cutouts in that same area of the transition so I can keep it semi stock quiet when I want.

Pursuit
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Re: ZL1 Bimodal Exhaust

Post by Pursuit » Wed Jan 11, 2017 12:05 am

Still 2-1/2". I was glad to get rid of the L99 "suit case" baffle. Splicing right behind it for a slip fit created sagging problems against the rear flat cross member. This is a much sturdier, and I am assuming, lighter system.

Maurice
Maurice Sheil

mhsheil@gmail.com

2011 Caprice Phantom Black 9C3
2012 Impala 9C1
1995 9C1 Caprice
1996 GMC Sierra C1500
1974 SJ Grand Prix 455 well optioned with factory moon roof

indianajoe
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Location: South Bend, IN

Re: ZL1 Bimodal Exhaust

Post by indianajoe » Wed Jan 11, 2017 12:19 am

looks good so far!
i've always wondered how hard it would be to put the c6 z06 mufflers i see for sale on...

how come you went with a single exhaust tip instead of dual?

Pursuit
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Re: ZL1 Bimodal Exhaust

Post by Pursuit » Wed Jan 11, 2017 12:28 am

These were the Camaro ZL1 mufflers. And, I have just not ever been a fan of dual tips. Never even used the ones from the Solo Axle back kit.

Maurice
Maurice Sheil

mhsheil@gmail.com

2011 Caprice Phantom Black 9C3
2012 Impala 9C1
1995 9C1 Caprice
1996 GMC Sierra C1500
1974 SJ Grand Prix 455 well optioned with factory moon roof

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No Moa
Posts: 470
Joined: Wed Sep 21, 2016 2:30 am
Location: Maine

Re: ZL1 Bimodal Exhaust

Post by No Moa » Wed Jan 11, 2017 2:23 am

Looks good. I'm struggling with picking exhaust. And wheels and tires, and about 6 other things. Lol
2014 Caprice PPV silver
2017 Ram 3500
2002 CETA trans am
1996 Impala ss (soon to be t56)
1995 9c1
1977 Trans am SE 4spd.
1978 trans am 400 4 spd.

brenard
Posts: 27
Joined: Mon May 04, 2015 3:22 am

Re: ZL1 Bimodal Exhaust

Post by brenard » Thu Jan 19, 2017 10:32 am

Looks good. Nice job. So how's the sound?

Fraley
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Joined: Mon Jan 15, 2018 12:10 pm

Re: ZL1 Bimodal Exhaust

Post by Fraley » Sun Jan 21, 2018 9:39 am

Yeah looks nice! I would love to see a video of it in action so I can hear what it sounds like. I bet it sounds awesome!

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