10-13-2021, 09:42 AM | #15 | |
Drives: 2019 ZL-1 Join Date: Feb 2009
Location: Troy, MI & Naples, FL
Posts: 2,019
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Quote:
This..... Thw 2005-2006 GTO's had the same pinch....ZERO loss
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2019 ZL-1 Acquired 4/23/21 at 6300 miles. Riverside Blue, A10, PDR. Traded in 2017 2SS with 6M and 32k miles. Continental Extreme Contact Sports. Now has 10,000 miles...
2012 Yukon XL Denali w/ 6.2 AWD |
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10-13-2021, 09:59 AM | #16 |
Drives: 2013 Triple Black ZL1 Vert M6 ECF Join Date: Mar 2011
Location: Trenton, Michigan
Posts: 7,047
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It has been demonstrated in the past that even though the tube is 'crushed' a bit, the cross section area remains the same, resulting in 'no' loss of performance.
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10-13-2021, 11:27 AM | #17 |
Drives: Hyper Blue 2016 2SS 6M Join Date: Sep 2017
Location: North Ga
Posts: 1,787
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The cross section is reduced a bit, but not enough to affect performance
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Baby Blue
2016 Hyper Blue 2SS/6m/MRC/NPP/Silver Rally stripes/ZL1 wheels & brakes/GForce DS and axles/ZLE Cradle Bushings/FE4 ARB front & rear/SEMA Grill/Rotofab dry/95mm TB/Magnuson 2300/Full LT4 fuel system/JMS boost-a-pump/E85 Sensor/Ported CID heads from LME/Cammotion PD cam/Thompson Motorsports forged shortblock/catted Kooks 1 7/8 headers /JRE remote tuned |
10-13-2021, 11:44 AM | #18 |
Drives: 2016 2SS, Red Hot, NPP, Nav, M6 Join Date: Jul 2016
Location: Eagle Creek OR
Posts: 783
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I got rid of mine as it was just against my grain to have these in place. Just wasn't right in my mind.
I got the Hooker BlackHeart crush pipe delete kit and my cut off wheel and replaced them last year. No difference in performance is all I hear & read, but I would swear there is a bit of a difference in the NPP sound. To me, it was worth it. After all, modding a performance car is about personally getting your hands on it and tweaking, at least for me. I am an engineer and believe in the data shown, but fluid dynamics were on my mind and even though cross section remains the same, the turbulence is not. For the low cost of the kit, I decided to do it. Measure twice or more before cutting though. The directions provided in the kit were not totally clear. |
10-13-2021, 12:07 PM | #19 |
Drives: '20 ZLE Join Date: Jun 2020
Location: Mile High
Posts: 3,564
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The crimped section has been discussed here endlessly, but it bugs me that, even when you add, say, 50 to 100% more CFM to these high hp engines, that the crimp wouldn't add back pressure.
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'20 ZL1 1LE A10,
OEM short block, LME heads/valve train, E2650. 100+ octanes, no eth, no meth, no N2O. 2/23 - 1031/1004 wheel. 4/23 - 1.41/9.61/145 at DA 7000 ft. (only made five passes). 2/24 - LME 390, E2650, FBO, 100 oct.; 1116hp/ 1063tq; 109 oct. dyno next. |
10-13-2021, 12:57 PM | #20 | |
Drives: 19 Chevrolet Camaro 2SS 1LE Shock Join Date: Apr 2020
Location: BC, Canada
Posts: 1,947
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Quote:
What's next? Your engine air filter has a leaf on it? Tires have too many rocks on it? Didn't remove your back seats?
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Current:
2019 Chevrolet Camaro 2SS 1LE M6 Shock GM Performance Intake and that's it, because driver mods before car mods Past: 2009 Mazda RX-8 GT M6 Velocity Red Mica (Sold) 2015 Chevrolet Corvette Z51 2LT M7 Velocity Yellow Tintcoat (Flood totaled) |
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10-13-2021, 01:02 PM | #21 | |
Drives: Hyper Blue 2016 2SS 6M Join Date: Sep 2017
Location: North Ga
Posts: 1,787
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Quote:
Think about it! You’re an engineer! The cross section isn't the same: The exhaust pipe just before/after the crushed section is 2.75” which works out to a circumference of 8.64” and a cross sectional area of 5.94”. Ignoring any stretching of the pipe resulting from the forming process and discounting the radii at the corners, when considering rectangular sections, a square will give you the max possible cross-sectional area. In our case, we have 8.64 inches to work with, which gets you a 2.16 x 2.16 square with a cross sectional area of 4.67sqin. It gets worse the flatter the rectangle. Ex: a 3.5 x 1.32 rectangle (3.5 + 3.5 + 1.32 + 1.32 = 8.64) nets you a cross section of 4.62sqin. A really flat section of, say 4 x .32 is only 1.28sqin.
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2016 Hyper Blue 2SS/6m/MRC/NPP/Silver Rally stripes/ZL1 wheels & brakes/GForce DS and axles/ZLE Cradle Bushings/FE4 ARB front & rear/SEMA Grill/Rotofab dry/95mm TB/Magnuson 2300/Full LT4 fuel system/JMS boost-a-pump/E85 Sensor/Ported CID heads from LME/Cammotion PD cam/Thompson Motorsports forged shortblock/catted Kooks 1 7/8 headers /JRE remote tuned |
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10-13-2021, 01:37 PM | #22 |
Drives: '20 ZLE Join Date: Jun 2020
Location: Mile High
Posts: 3,564
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Confirming that the crimp has no impact on hp or torque https://www.mishimoto.com/engineerin...he-crimp-myth/
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'20 ZL1 1LE A10,
OEM short block, LME heads/valve train, E2650. 100+ octanes, no eth, no meth, no N2O. 2/23 - 1031/1004 wheel. 4/23 - 1.41/9.61/145 at DA 7000 ft. (only made five passes). 2/24 - LME 390, E2650, FBO, 100 oct.; 1116hp/ 1063tq; 109 oct. dyno next. |
10-13-2021, 02:01 PM | #23 | |
Drives: 20’ Chevrolet Camaro 2SS 1LE Join Date: Jan 2009
Location: San Diego
Posts: 1,577
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Quote:
Seems to me it would offer better exhaust flow, I’m not an engineer.
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10-13-2021, 02:12 PM | #24 |
Drives: 2011 2SS/RS LS3 Join Date: Nov 2011
Location: Torrance
Posts: 14,432
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Drill a couple of small holes (1/4" or so) in the crimped area to compensate for the restriction. Good luck.
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10-13-2021, 03:32 PM | #25 |
Drives: SS 1LE, 89 TTA, 91 GTA, 91 Formula Join Date: Jul 2019
Location: NW IN
Posts: 600
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The farther u move a restriction from the exhaust the less of a restriction it is
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10-13-2021, 04:33 PM | #26 |
Drives: 2021 Camaro ZL1 A10 Join Date: Nov 2018
Location: Idaho
Posts: 1,212
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Mechanical engineer here...Technically, the crimp adds a tiny bit of back pressure in the exhaust since there is a transition from round to...oval-ish, and back to round, and there is a slight reduction in cross sectional area which means the velocity will increase, and thus, so will the frictional/dynamic losses in that section compared to the rest of the round piping. That said, the crimped pipe segment is so short that it likely has a negligible effect on exhaust performance, and thus little to no effect on engine power.
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2021 Camaro ZL1 A10
2022 GR Supra 3.0 Past: 2018 Mustang GT Premium w/ PP1, MR, and A10 2007 MazdaSpeed3 1995 Pontiac Trans Am 1987 Camaro Z28 |
10-13-2021, 05:23 PM | #27 | |
Drives: Hyper Blue 2016 2SS 6M Join Date: Sep 2017
Location: North Ga
Posts: 1,787
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Quote:
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Baby Blue
2016 Hyper Blue 2SS/6m/MRC/NPP/Silver Rally stripes/ZL1 wheels & brakes/GForce DS and axles/ZLE Cradle Bushings/FE4 ARB front & rear/SEMA Grill/Rotofab dry/95mm TB/Magnuson 2300/Full LT4 fuel system/JMS boost-a-pump/E85 Sensor/Ported CID heads from LME/Cammotion PD cam/Thompson Motorsports forged shortblock/catted Kooks 1 7/8 headers /JRE remote tuned |
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10-13-2021, 05:35 PM | #28 | |
corner barstool sitter
Drives: 08 Mustang GT, 19 WRX Join Date: Jul 2012
Location: Eastern Time Zone
Posts: 6,990
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Quote:
You should probably be thinking a bit deeper than simply outside cross-sectional area (you did consider that inside areas are not based directly on the OD measurement?). But even running with outside 2.75" OD and 8.64" circumference dimensions, a 3 x 1.32 rectangle provides (3 + 3 + 1.32 + 1.32) = 3.96 in^2, or about 85% of the 2.16 x 2.16 square. I don't blame you for not wading through the round to flat oval math, but I think that the inside area reductions don't happen as rapidly (I think the area loss going from a 2.75" circle down to a 2.2.5" x 3.75" flat oval runs a lot closer to 5%). Feel free to check this. Beyond that, flow restriction is also a function of how long the restriction is, relative to the unrestricted length. This is at least part of the reason you can get away with dimpling header primary tubes for clearance without losing power until you've really choked the inside area down. Norm
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'19 WRX 6M (the family sedan . . . seriously) |
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