01-30-2018, 08:37 PM | #1 |
Drives: '17 ZL1 Join Date: Jul 2016
Location: Fairmont, WV
Posts: 1,558
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What's the purpose of the crimped exhaust?
Al,
What function is provided by the crimps in the section of exhaust pipe near the rear differential? Thank you! (I’m not certain if this exists on all trims. It is at least present on the SS and ZL1.)
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01-30-2018, 09:31 PM | #2 |
Drives: 2017 1SS 1LE Join Date: Aug 2017
Location: New Jersey
Posts: 391
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It is crimped to allow a common pet number between the coupes and the convertibles. The convertibles have a brace there which the coupes do not have.
It does not materially impact power, though it does impact sound. Source: I asked a GM engineer who worked on the development of the car. |
02-01-2018, 07:10 AM | #3 | |
Drives: '17 ZL1 Join Date: Jul 2016
Location: Fairmont, WV
Posts: 1,558
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Quote:
Does anybody have a picture of this brace that the exhaust must avoid? I tried googling, but I didn't find an actual picture.
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02-01-2018, 02:27 PM | #4 |
The Mechanic
Drives: 1SS M Join Date: Dec 2017
Location: NJ
Posts: 291
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How does this not affect power? Does it have the same total inside area?
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02-01-2018, 02:46 PM | #5 |
CamaroFans.com
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At one time there was an issue with some aftermarket exhaust systems that touched the cross member and slight rattle caused the appearance of knock which would retard timing and pull power.
Not something you want to deal with. Crimps have definitely been shown as a non-issue as far as power is concerned. |
02-01-2018, 02:57 PM | #6 |
Drives: 17 SS a8 Join Date: Feb 2010
Location: omaha
Posts: 1,678
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One company ran one test a couple of years ago and saw no gain removing them. Another company recently shows a gain removing them. I can tell you removing them along with the afm valves was my first mod.
I would estimate they are crushed to 60% of their original cross section.
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dropped a valve in the 6.2. now running a drop in rods and piston 5.3
best et 5.83@121 with the 5.3 http://www.camaro6.com/forums/showthread.php?t=465472 |
02-01-2018, 04:11 PM | #7 | |
Moderator.ca
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Quote:
That crushed area is what ... 4, maybe 6 inches in length? So no more than about 5% of the total length. Now, its still fairly close to the same overall area. Maybe it increases restriction in that one little section by 20%. To make the math simple, lets say there was maybe 10 hp lost along the total length of pipe from the engine to the tips. 1 hp/foot. This little 6 inch section, if it were full diameter, would then be robbing you of a whole 1/2 a horsepower. But since its flattened on the one side making it a bit more restrictive its now like 0.6 hp. A difference of 0.1 hp from a 'perfect' pipe. Oh wait, there's two parallel sides ... so its total for the system of 0.2 hp. Give or take. You're not going to notice that tiny of a difference on a dyno, let alone out in the world. I'm just guestimating my numbers here. But even if I'm way off, its still hard to get it to work out to more than about 1 hp extra compared to a perfect pair of pipes.
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Note, if I've gotten any facts wrong in the above, just ignore any points I made with them
__________________ Originally Posted by FbodFather My sister's dentist's brother's cousin's housekeeper's dog-breeder's nephew sells coffee filters to the company that provides coffee to General Motors...... ........and HE WOULD KNOW!!!!__________________ Camaro Fest sub-forum |
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02-01-2018, 05:02 PM | #8 |
Drives: 17 SS a8 Join Date: Feb 2010
Location: omaha
Posts: 1,678
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here is what holly is claiming with their crush pipe delete kit.
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dropped a valve in the 6.2. now running a drop in rods and piston 5.3
best et 5.83@121 with the 5.3 http://www.camaro6.com/forums/showthread.php?t=465472 |
02-01-2018, 05:08 PM | #9 |
Drives: '17 ZL1 Join Date: Jul 2016
Location: Fairmont, WV
Posts: 1,558
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Those dyno runs were 5 months apart. I'm not saying I don't believe it... well... yeah I am. I don't believe it.
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02-01-2018, 05:14 PM | #10 |
Drives: 17 SS a8 Join Date: Feb 2010
Location: omaha
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like I said above one place says 0 gain. everyone believes it and preaches it. another place says 12hp. for the cost to get rid of it was a no brainer for me. most people considering this mod will or have all ready done other mods. it would be great to see a same day test.
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dropped a valve in the 6.2. now running a drop in rods and piston 5.3
best et 5.83@121 with the 5.3 http://www.camaro6.com/forums/showthread.php?t=465472 |
02-01-2018, 07:42 PM | #11 | |
Moderator.ca
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Quote:
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Note, if I've gotten any facts wrong in the above, just ignore any points I made with them
__________________ Originally Posted by FbodFather My sister's dentist's brother's cousin's housekeeper's dog-breeder's nephew sells coffee filters to the company that provides coffee to General Motors...... ........and HE WOULD KNOW!!!!__________________ Camaro Fest sub-forum |
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02-01-2018, 08:07 PM | #12 |
Drives: 17 SS a8 Join Date: Feb 2010
Location: omaha
Posts: 1,678
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I agree. it would be great if someone did some back to back tests. this question comes up at least once a month, it would be great to have a little more data on it.
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dropped a valve in the 6.2. now running a drop in rods and piston 5.3
best et 5.83@121 with the 5.3 http://www.camaro6.com/forums/showthread.php?t=465472 |
02-01-2018, 08:16 PM | #13 | |
Drives: Crush ZLE M6 | 2000 Corvette FRC Join Date: Jun 2010
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02-01-2018, 10:12 PM | #14 |
Drives: Grandad's C2 L89 Join Date: May 2017
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2018 ZL1 1LE sw/PDR
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