10-29-2020, 04:56 PM | #29 | |
Drives: 2017 Camaro 1SS M6 Join Date: Apr 2015
Location: Indy
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I don't think that's accurate. You could increase (or decrease) tire diameter and it theoretically would not impact the engine speed drop between shifts assuming the engine speed at which the shift is initiated remains the same. Similarly, you could change the rear end gear ratio and it also wouldn't affect the engine speed drop between gears. The engine speed drop between gears is a function of the transmission gear ratios.
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2017 Camaro 1SS, M6, Hurst shifter, Hyper Blue, NPP, Gray Split Spoke Wheels
Best 1/4 Mile: 12.24 @ 115.9 mph Last edited by vtirocz; 10-29-2020 at 06:36 PM. |
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10-29-2020, 05:43 PM | #30 |
Drives: like an old lady Join Date: Jun 2012
Location: indiana
Posts: 2,395
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speed vs rpm for a given tire size. the other (mechanical) variables and trans gearing never change.
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2016+ camaro: everyone’s first car
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10-29-2020, 06:49 PM | #31 | |
Drives: 2021 LT1 10 speed auto Join Date: May 2013
Location: Connecticut
Posts: 2,343
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10-30-2020, 05:09 AM | #32 | |
Drives: 2017 Camaro 1SS Join Date: Aug 2016
Location: NH
Posts: 1,692
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10-30-2020, 08:27 AM | #33 | |
Drives: 2017 Camaro 1SS M6 Join Date: Apr 2015
Location: Indy
Posts: 2,460
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I disagree with that. Assuming the shift is initiated at the exact same engine speed (6500rpm for instance), the engine speed after the shift is completely independent of rear axle ratio and tire size (instead it's a function of the transmission gearing). I've calculated this out just to confirm I'm correct here. I guess there could be vehicle acceleration differences between the shift that could play into this, but I'd expect that to be a small difference. I agree with the other points from your prior post.
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2017 Camaro 1SS, M6, Hurst shifter, Hyper Blue, NPP, Gray Split Spoke Wheels
Best 1/4 Mile: 12.24 @ 115.9 mph |
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10-30-2020, 09:13 AM | #34 |
Drives: 2016 1SS NFG A8 Join Date: Aug 2017
Location: 46804
Posts: 6,796
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The confusion is on my part when I said that the rpm drops lower on gear change but that is incorrect. The shorter tire will put you at a lower mph at the same rpm as the taller tire. or another way to say it is the taller tire will be at a lower rpm at the same mph as the shorter tire...that is what I was thinking when I referenced it to RPM drop. My mistake you are correct.
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2016 NFG 1SS A8
Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA |
10-30-2020, 09:32 AM | #35 |
Drives: Hyper Blue 2016 2SS 6M Join Date: Sep 2017
Location: North Ga
Posts: 1,786
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Oh hell yes, 1.95 is a good 60'! I'll have to check my time slips, but I believe 1.90 is my best to-date, and that's on your old drag pack, Greg. I love my m6, but A8 or A10 is the only way to roll on the strip.
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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 |
10-30-2020, 10:08 AM | #36 | |
Drives: 2017 Camaro 1SS M6 Join Date: Apr 2015
Location: Indy
Posts: 2,460
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With a drag radial, I'd hope for a 0.2sec improvement.
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2017 Camaro 1SS, M6, Hurst shifter, Hyper Blue, NPP, Gray Split Spoke Wheels
Best 1/4 Mile: 12.24 @ 115.9 mph |
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10-31-2020, 05:53 PM | #37 | |
Drives: 2021 LT1 10 speed auto Join Date: May 2013
Location: Connecticut
Posts: 2,343
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10-31-2020, 06:07 PM | #38 |
Drives: 2016 1SS NFG A8 Join Date: Aug 2017
Location: 46804
Posts: 6,796
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I don't have any issues with a taller tire on the back either. I run stock size 245/40/20 front with 305/35/20 rear. They are rated 28.4 tall but measure 27.9 loaded so that is what I plugged into the tune to calibrate the speedo and shift points. The speedo is dead on with my Dragy. I do agree you want to let the ECU know that you changed tire height mainly so it can adjust the shift points and correct the speedo.
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2016 NFG 1SS A8
Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA |
11-01-2020, 04:23 AM | #39 |
Drives: 2017 Camaro 1SS Join Date: Aug 2016
Location: NH
Posts: 1,692
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As far as tire size and Stabilitrack, I found the same thing as KingLT1 did with tall rears on my SS. The taller rear tire (305/45-17) with the stock size front tire did not bother it. However, a smaller rear tire (275/40-17) with stock size front tire freaked the car out like Yosh6 mentioned. Warning lights lit up and car went into some weird limp thing. Due to this, ended up turning the nannies off with the ~10sec hold of TC button to drive the car with the shorter rears. With the shorter tire, I had adjusted the speedometer per their spec before driving the car, but it freaked out in less than a mile.
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11-01-2020, 01:47 PM | #40 |
Drives: 2017 Camaro 1SS Join Date: Aug 2016
Location: NH
Posts: 1,692
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Subject of changing the speedo for a different tire, I had tried it when my TCM was still locked (pertinent to the 2020+ auto owners). Car was 2017 SS A8 with MT 305/45-17 DRs on the back. I had found that these were taller than stock, and the car was able to get 116mph in 4th gear at 6500rpm with the stock tune. With these tires on, traction was better, but the shifting with the locked tcm was worse than with the stock tires. I did try changing the speedo cal for them, but shifting remained roughly the same as with the stock speedo calibration. Illustration below, the 109mph is with stock speedo calibration and the 114mph is with speedo calibration adjusted closer to the MT's actual size. The cursor is at top of 4th gear.
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11-02-2020, 02:00 PM | #41 | |
Drives: 2018 Camaro SS 1LE Join Date: Aug 2018
Location: Tampa Florida
Posts: 1,980
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Excited to see what the new a10 1le's do with the 2.85 rear end.
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11-02-2020, 02:57 PM | #42 | |
Drives: 2021 LT1 10 speed auto Join Date: May 2013
Location: Connecticut
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