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Old 11-17-2022, 11:17 AM   #15
JimGnitecki
 
Drives: Chevrolet Camaro LT1
Join Date: Sep 2022
Location: Alberta
Posts: 268
Quote:
Originally Posted by 6spdhyperblue View Post
I see it as they were ahead of the game as basically everyone is using TM now.

going to first just blows the tire off and you donít need that level of gearing if youre at a decent roll already(those gears are all short and I see you have a 2650, do you even need 1st gear at all?!?!). In second, youíre in the meat of the torque curve and you eliminate the time of the shift. I bet itís faster that way. But you can measure it both ways and let us know

Lastly when youíre roll racing or doing those pulls, you should already be in the gear you want to be in waiting for the ďgoĒ. So if thatís first you should be manually putting it into first. Then when you mat it u let the trans do the shifting. To do this
Move the shifter over and get into the gear you need to be in. Once you hit the gas you move the shifter back over to D and let it do itís thing.
That will provide the best result from a roll
I am reluctant to move the shift lever WHILE applying WOT. Just not comfortable with that, for mechanical reasons as well as for safety (I want both hands on the steering wheel when applying WOT).

Jim G
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Old 11-17-2022, 12:46 PM   #16
JimGnitecki
 
Drives: Chevrolet Camaro LT1
Join Date: Sep 2022
Location: Alberta
Posts: 268
Quote:
Originally Posted by 6spdhyperblue View Post
I see it as they were ahead of the game as basically everyone is using TM now.

going to first just blows the tire off and you don’t need that level of gearing if youre at a decent roll already(those gears are all short and I see you have a 2650, do you even need 1st gear at all?!?!). In second, you’re in the meat of the torque curve and you eliminate the time of the shift. I bet it’s faster that way. But you can measure it both ways and let us know

Lastly when you’re roll racing or doing those pulls, you should already be in the gear you want to be in waiting for the “go”. So if that’s first you should be manually putting it into first. Then when you mat it u let the trans do the shifting. To do this
Move the shifter over and get into the gear you need to be in. Once you hit the gas you move the shifter back over to D and let it do it’s thing.
That will provide the best result from a roll
I just ran the data through my performance modeling software, and you are correct about 1st gear not providing faster acceleration than 2nd gear, even from a standing start - at typical weight transfers to the rear wheels.

But that starts to change IF I could somehow transfer about 90% of the car's weight to the rear axle, and have a high enough coefficient of friction on the tire (like 1.2). IF I could get 100% to the rear axle (i.e. if I could get the front wheels to unload completely), and if I had rear tires with a 1.20 friction coefficient (possible on a dragstrip I assume), I would pick up about 0.2 second in the 0-60 run, and therefore also 0.2 seconds in the quarter mile, by using 1st gear versus 2nd gear from the standing start. This would be the case despite the fact that there would STILL be some tire spin in 1st gear (but not in 2nd gear).

Of course, I have no idea how I could get the front end to unload completely!

But it's an interesting theoretical.

Jim G
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Old 01-25-2023, 07:10 PM   #17
cmitchell17

 
Drives: 17 2SS, 8L90, Cam, Heads, E85
Join Date: Dec 2016
Location: US
Posts: 1,154
The 8L90 does this unnecessarily hard 3-4 shift at low to mid throttle range also. It is only for the 3-4 upshift and it sometimes doesn't do it at lower transmission temperatures.

I think it is just bad calibrating, and HP Tuners and TCM tuning will do nothing to fix it. The only thing HP Tuners is useful for when "tuning" the TCM is changing shift scheduling and if you want to completely turn off all torque limiting (not change it just turn it off completely). We lack the necessary tables to do anything with the TCMs on these and the ones available in HP Tuners don't function.
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