[Z06] Late Z06 Exhaust backdate
05-17-2013, 10:08 PM
#21
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Well, I know the correct doors at GMPT to knock on and I'm going to start learning more about it.
Makes sense that going from a straight H- to a X-pipe would increase performance.
I'll go farther and guess that GM probably knew the new reg. in California, which forced the four-cat exhausts, was coming and it knew they'd have to do something to keep the power rating where it was in-spite of the additional back pressure they'd get with two more cats. Easiest thing to do was go from an H- to an X-pipe along with adding the ZR-1 filter so they did it a year sooner.
One could also surmise that the 11's, as they had two rather than four cats, were the only cars which truly benefited from the change. The increase may have been negated by the two extra cats on 12s and 13s.
Comments?
Makes sense that going from a straight H- to a X-pipe would increase performance.
I'll go farther and guess that GM probably knew the new reg. in California, which forced the four-cat exhausts, was coming and it knew they'd have to do something to keep the power rating where it was in-spite of the additional back pressure they'd get with two more cats. Easiest thing to do was go from an H- to an X-pipe along with adding the ZR-1 filter so they did it a year sooner.
One could also surmise that the 11's, as they had two rather than four cats, were the only cars which truly benefited from the change. The increase may have been negated by the two extra cats on 12s and 13s.
Comments?
Last edited by Hib Halverson; 05-17-2013 at 10:12 PM. Reason: added content
05-17-2013, 10:19 PM
#22
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05-17-2013, 10:20 PM
#23
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As for the SAE "recertification", if I can get enough information about it, a revision to the LS7 article will be in order.
05-17-2013, 10:59 PM
#24
Team Owner
Well, I know the correct doors at GMPT to knock on and I'm going to start learning more about it.
Makes sense that going from a straight H- to a X-pipe would increase performance.
I'll go farther and guess that GM probably knew the new reg. in California, which forced the four-cat exhausts, was coming and it knew they'd have to do something to keep the power rating where it was in-spite of the additional back pressure they'd get with two more cats. Easiest thing to do was go from an H- to an X-pipe along with adding the ZR-1 filter so they did it a year sooner.
One could also surmise that the 11's, as they had two rather than four cats, were the only cars which truly benefited from the change. The increase may have been negated by the two extra cats on 12s and 13s.
Comments?
Makes sense that going from a straight H- to a X-pipe would increase performance.
I'll go farther and guess that GM probably knew the new reg. in California, which forced the four-cat exhausts, was coming and it knew they'd have to do something to keep the power rating where it was in-spite of the additional back pressure they'd get with two more cats. Easiest thing to do was go from an H- to an X-pipe along with adding the ZR-1 filter so they did it a year sooner.
One could also surmise that the 11's, as they had two rather than four cats, were the only cars which truly benefited from the change. The increase may have been negated by the two extra cats on 12s and 13s.
Comments?
05-18-2013, 01:06 AM
#26
Melting Slicks
Well, I know the correct doors at GMPT to knock on and I'm going to start learning more about it.
Makes sense that going from a straight H- to a X-pipe would increase performance.
I'll go farther and guess that GM probably knew the new reg. in California, which forced the four-cat exhausts, was coming and it knew they'd have to do something to keep the power rating where it was in-spite of the additional back pressure they'd get with two more cats. Easiest thing to do was go from an H- to an X-pipe along with adding the ZR-1 filter so they did it a year sooner.
One could also surmise that the 11's, as they had two rather than four cats, were the only cars which truly benefited from the change. The increase may have been negated by the two extra cats on 12s and 13s.
Comments?
Makes sense that going from a straight H- to a X-pipe would increase performance.
I'll go farther and guess that GM probably knew the new reg. in California, which forced the four-cat exhausts, was coming and it knew they'd have to do something to keep the power rating where it was in-spite of the additional back pressure they'd get with two more cats. Easiest thing to do was go from an H- to an X-pipe along with adding the ZR-1 filter so they did it a year sooner.
One could also surmise that the 11's, as they had two rather than four cats, were the only cars which truly benefited from the change. The increase may have been negated by the two extra cats on 12s and 13s.
Comments?
05-18-2013, 01:06 PM
#27
Drifting
Funny you should mention this
When I was at Laguna Seca last weekend, one of the Vette engineers that had done a presentation at the Corvette Corral walked over to my car and starting asking me about the Z07 package and how much he liked the 2011 Z06. I was a bit surprised though happy that he would say that and he mentioned how the 2011 Z06 had a "different" exhaust system with a different sound due to the cats in the system. I was aware of the X pipe cross over but not aware of the car setup. He just smiled and and said that it was bit louder and that GM changed it for 2012 and 2013. Anyway I am guessing that is why you want to swap for the 2011 setup?? He asked that I not mention his name if I talked about this on the forum. Seems that the hot setup is on the 2011. Makes me happy.
Last edited by Crossofiron; 05-18-2013 at 01:13 PM.
05-18-2013, 02:36 PM
#28
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I want to change it for testing because '11 had the X-pipe and two cats whereas the 12s and 13s have four cats. I want to learn what the difference is.
05-18-2013, 02:38 PM
#29
Team Owner
Well, we know when they removed the "pup" cats from the C5 Z06 in 2002, the HP increased to 405 from 385 (20 HP), and the claim from GM for the increase was the removal of those cats as I recall. Makes sense that the additional cats on '12-'13 C6Zs would cost some power unless they have some new design feature (lo-flo).
05-18-2013, 02:43 PM
#30
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Well, we know when they removed the "pup" cats from the C5 Z06 in 2002, the HP increased to 405 from 385 (20 HP), and the claim from GM for the increase was the removal of those cats as I recall. Makes sense that the additional cats on '12-'13 C6Zs would cost some power unless they have some new design feature (lo-flo).
It is true that 01 Z06es had pup cats and, by their nature, they were pretty restrictive
The difference in power between 01 (385) and 02-04 (405) Z06es comes with 1) removal of pup cats and a new main cat design but, also, from 2) the bigger cam, lighter valves, screenless MAF and a different air box cover. My guess is most of the 20 more horses is from the valvetrain changes.
The second set of cats on a 12 and 13 are not really "pup cats" in the sense that they are a significant restriction, at least, they don't look that way.
I guess the right thing to do is drill the system ahead of the second set of cats and measure the back pressure.
05-18-2013, 04:58 PM
#31
Melting Slicks
Your information on the C5 Z06es is not quite correct.
It is true that 01 Z06es had pup cats and, by their nature, they were pretty restrictive
The difference in power between 01 (385) and 02-04 (405) Z06es comes with 1) removal of pup cats and a new main cat design but, also, from 2) the bigger cam, lighter valves, screenless MAF and a different air box cover. My guess is most of the 20 more horses is from the valvetrain changes.
The second set of cats on a 12 and 13 are not really "pup cats" in the sense that they are a significant restriction, at least, they don't look that way.
I guess the right thing to do is drill the system ahead of the second set of cats and measure the back pressure.
It is true that 01 Z06es had pup cats and, by their nature, they were pretty restrictive
The difference in power between 01 (385) and 02-04 (405) Z06es comes with 1) removal of pup cats and a new main cat design but, also, from 2) the bigger cam, lighter valves, screenless MAF and a different air box cover. My guess is most of the 20 more horses is from the valvetrain changes.
The second set of cats on a 12 and 13 are not really "pup cats" in the sense that they are a significant restriction, at least, they don't look that way.
I guess the right thing to do is drill the system ahead of the second set of cats and measure the back pressure.
. I seem to remember something about "windowing" the main bearing bosses also to help with "pumping" of air in the block (much like what is done on the LS7) is that true, or was that when the LS1 went from 345 to 350 HP?
05-18-2013, 05:16 PM
#32
Race Director
05-19-2013, 07:43 PM
#33
Team Owner
I recall...I almost went down that road because of your post. Then I found a custom x-pipe at a local shop that was a take off form a customer car...picked it up for a great deal.
Then I found a custom x-pipe at a local shop that was a take off form a customer car...picked it up for a great deal.
Last edited by MTPZ06; 05-19-2013 at 07:46 PM.
05-22-2013, 07:36 PM
#34
Safety Car
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Hib:
I am pretty sure MarkRx did this swap on his 2012, specifically because of the difference in the exhaust sound and performance. I remember him posting some info about it. You should be able to do a search and fnd it.
I am pretty sure MarkRx did this swap on his 2012, specifically because of the difference in the exhaust sound and performance. I remember him posting some info about it. You should be able to do a search and fnd it.
05-22-2013, 08:01 PM
#35
I added this same x-pipe with my Borla catback. Love the sound. I always wondered if the exhaust is what made the 2011 z06 I drove feel slower than the 09 I have. And yes it was a pretty significant difference of course the 09 had 14k miles the 11 had only a few hundred.
02-06-2014, 10:45 PM
#36
Melting Slicks
In July 2010 the 2011 GMX-245 LS7 was SAE J1349 re-certified at 505/470, but made the 470 at 4400 rpm vs. 4800 rpm and the 505 HP at 5800 rpm vs. 6300 rpm.
GM claimed wave mixing and back pressure change in the exhaust (mid-pipe change) as their reason for the updated certification.
Obviously the mid pipe "wave mixing" resulted in the same certified power as the 2005 dyno of the GMX-245 LS7 SAE J1349, but at 400 rpm sooner for torque and 500 rpm sooner for horsepower. You have to wonder what the horsepower number was at 6300 rpm, since I have verified that the cams for 2006 and 2011 are the same part number. (Thanks to Glass Slipper)
For a mere $1000 you could have the full dyno pull for your wall.
By the way, the SAE Re-Certification stated 505@4800 rpm for the HP!! Obviously a typo. Had to be 5800 rpm.
GM claimed wave mixing and back pressure change in the exhaust (mid-pipe change) as their reason for the updated certification.
Obviously the mid pipe "wave mixing" resulted in the same certified power as the 2005 dyno of the GMX-245 LS7 SAE J1349, but at 400 rpm sooner for torque and 500 rpm sooner for horsepower. You have to wonder what the horsepower number was at 6300 rpm, since I have verified that the cams for 2006 and 2011 are the same part number. (Thanks to Glass Slipper)
For a mere $1000 you could have the full dyno pull for your wall.
By the way, the SAE Re-Certification stated 505@4800 rpm for the HP!! Obviously a typo. Had to be 5800 rpm.
I have posted my 100% stock 2011 Z06 dyno's below (when the motor still had less than 1,000 miles on it!) to show the difference in power & torque at the certified/advertised RPM's versus the actual peak power made below.
It's interesting to note that with the X-pipe the motor's peak power was actually at ~6200 RPM, up +4RWHP from the certified 5800 RPM.
The peak RWTQ difference is pretty significant....my peak RWTQ is at ~5000 RPM vs the 4400RPM certification for a +7RWHP difference! (444 vs 451!)
I think that it would be fair to say that if the 2011 LS7 motor was rated at peak HP/TQ rather than artificially low RPM values that the numbers would likely be in the 510/480 range
Of course to lower the rating on the 2012/2013's due to the extra cats would be a morale deflator for cars sales and would be buyers.
It's too bad that so many people are losing interest in the C6Z.....I think it still rocks
02-08-2014, 12:25 PM
#37
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I finished my '11 exhaust retrofit two weeks ago. The car sounds a little louder and it feels different in the mid-range.
I've got a chassis dyno date at Westech on the 28th.
I'll post the results after the test.
I've got a chassis dyno date at Westech on the 28th.
I'll post the results after the test.
02-25-2014, 11:35 AM
#39
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