[2023_ZL1-AUTO]

radz28 - I was advised by my tuner this spring, for a 2nd gear burn out, keep the wheel speed MPH a little under the auto shift point. I think he mentioned, start the burn out in 2nd gear, get the tires smoking hot and then roll out of the burn out box (around 80mph wheel speed would be good) Again ,that last part I'm kind of remember back.

[ZLRob]

Originally Posted by SOCAL.M6.ZLE

Well said Rob... I agree with you and others about being careful with boost on a stock blower... the benefits of focusing on E85 first... cooling mods... and then porting the blower first. Man I wish these cars came with an ethanol sensor :(

Me too. I think it would have eliminated a lot of issues that so many of us run into living in certain areas of the country that either don't have or don't allow the use of 93 octane at fuel stations.

Cooling on these cars is everything. Though, that can be said about pretty much any FI vehicle.

[radz28]

Originally Posted by 2023_ZL1-AUTO

radz28 - I was advised by my tuner this spring, for a 2nd gear burn out, keep the wheel speed MPH a little under the auto shift point. I think he mentioned, start the burn out in 2nd gear, get the tires smoking hot and then roll out of the burn out box (around 80mph wheel speed would be good) Again ,that last part I'm kind of remember back.

I think 2nd only goes out to 60, but I have been wrong many times. That, regardless, would keep from downshifting into 1st, so that makes complete sense.

Thanks for clearing that up for me, Scott!

[KingLT1]

Originally Posted by 2023_ZL1-AUTO

radz28 - I was advised by my tuner this spring, for a 2nd gear burn out, keep the wheel speed MPH a little under the auto shift point. I think he mentioned, start the burn out in 2nd gear, get the tires smoking hot and then roll out of the burn out box (around 80mph wheel speed would be good) Again ,that last part I'm kind of remember back.

Second gear doesn't go to 80mph


Rad,

I have seen some(Pray and GPI) recommend not to shift through the burnout, some have had trans failures from it. I would probably just stick to a second gear burn out. I have not seen or heard of any updates with trans tuning safely allowing for it. Built trans may be different.

[radz28]

Thanks King'. Got it.

I think 3rd tops out right at about 80, at stock shift points anyways.

[Megahurtz]

Pretty sure King is correct

The 10 Speeds essentially you just lock out 1st gear permanently so it never shifts into 1st. The 8 speeds you can still use 1st but you can shift into second and start in second gear.

Not sure if there are any updates to this as I don't do the second gear start too often and once its done its done. I'd have to go check some tune files.

[2023_ZL1-AUTO]

hahah!!!! OK That's why I made sure I said " I think he mentioned, start the burn out .... " It's was mostly said, RPM as high as you can with out it shifting would be a better way to describe it.

Thanks for clarifying that for me !!!

[Akura]

Sorry, but I’m not sure I understood correctly… so are you saying that using first gear in our A10 (stock trans) cars, after they’ve been tuned, is actually harmful?

[arpad_m]

Originally Posted by Akura

Sorry, but I’m not sure I understood correctly… so are you saying that using first gear in our A10 (stock trans) cars, after they’ve been tuned, is actually harmful?

It isn't harmful. Drag racers are looking to launch from 2nd gear, because it's much easier to get traction and you still have enough wheel torque to maximize it.

The 8-speed transmission (8L90) in the 2016-2018 SS allows you to shift up to 2nd gear with the car stopped, but for the 10L90, possibly only in later model years, GM seems to have changed the programming to disallow it.

[Akura]

Originally Posted by arpad_m

It isn't harmful. Drag racers are looking to launch from 2nd gear, because it's much easier to get traction and you still have enough wheel torque to maximize it.

The 8-speed transmission (8L90) in the 2016-2018 SS allows you to shift up to 2nd gear with the car stopped, but for the 10L90, possibly only in later model years, GM seems to have changed the programming to disallow it.

Understood, thank you!

[Megahurtz]

Originally Posted by Akura

Sorry, but I’m not sure I understood correctly… so are you saying that using first gear in our A10 (stock trans) cars, after they’ve been tuned, is actually harmful?

Originally Posted by arpad_m

It isn't harmful. Drag racers are looking to launch from 2nd gear, because it's much easier to get traction and you still have enough wheel torque to maximize it.

The 8-speed transmission (8L90) in the 2016-2018 SS allows you to shift up to 2nd gear with the car stopped, but for the 10L90, possibly only in later model years, GM seems to have changed the programming to disallow it.

Correct, but its not harmful. It just wont ever go into 1st gear. With the 10 speeds, you can do second gear start, but you actually tune 1st gear out completely so the car will never shift into 1st. That is the only way I know how to do it.

Most of my guys flash the 1st gear lockout TCM file for the track only since they still want 1st gear on the street.

[clg82]

Originally Posted by Megahurtz

Correct, but its not harmful. It just wont ever go into 1st gear. With the 10 speeds, you can do second gear start, but you actually tune 1st gear out completely so the car will never shift into 1st. That is the only way I know how to do it.

Most of my guys flash the 1st gear lockout TCM file for the track only since they still want 1st gear on the street.

Hmm that's a good idea, never thought of that.

[RHD ZL1]

Originally Posted by radz28

I'm sorry to the OP, but I suppose this little detour could be considered on-topic?...

King' - is it, still, a bad idea then, to not shift through multiple gears for the burn-out, then? Or am I mis-remembering, again... With the definitions from a couple years ago for the T93, if the appropriate ones are manipulated, is it safe to shift through multiple gears now, do you think?

No need to be sorry, in fact I can add to the discussion as I believe there is a bit of a grey area / misconception about shifting gears during a burnout.

I have done over 40 passes at the track over the last 3 odd years & have shifted into 6th gear on every single burnout with nil issues with my A10. I think it’s more about the method used during the burnout more so than “you shouldn’t shift multiple gears during a burnout”.

When I get into the burnout box, I shift into TUTD & the trans selects 2nd gear (that’s how I’ve calibrated the trans, dash display goes from “D” to “M2”). When I start the burnout I manually shift with the paddle shifter into 6th gear within a maximum of 1-1.5 car lengths of when starting the burnout. This ensures that all shifts take place while the tires are still in the water, this is similar to a dyno operator shifting gears on the dyno to get into 6th gear (IE: front wheels not moving or slowing rolling during a burnout, rear wheels turning and all shifts taking place with little to no load on the drivetrain, obviously more load during a burnout vs dyno but not enough load to hurt the A10). I believe that issues start when people start shifting gears as the tires start to hook during the burnout which then loads the drivetrain & clutch packs in the trans as the shift takes place due to the tires hooking. If you are shifting with little to no load on the drivetrain (while rear tires are still in the water) this is no different to shifting gears on a dyno to get the car into 6th as mentioned above yet there is no voodoo talk of not shifting multiple gears when on a dyno.

When I look at my logs during the burnout the engine isn’t even seeing boost during the 2-6 shifts, engine is around 90-95kpa and the rpm’s are up around 5,500 as the tires are still in the water so not generating any real load on the engine/drivetrain. Once into 6th I let off the brake pedal (I slightly apply brake with left foot) and then need to add more throttle as the car leaves the water and traction starts to increase, at that point where I start to tip in on the throttle in 6th is only when the engine starts to see boost however there are no more shifts taking place thereafter (pressure to the clutch packs are applied). The tires really start to smoke as I get into 6th due to wheel speed however you don’t need to be there for long.

If you start hearing the engine rpm be pulled down during the burnout due to the tires hooking, I certainly would not shift gears, I’d get off the throttle & consider the burnout over.

It is a 80 mile round trip to and from the track for me & as mentioned over the last 3 odd years I’ve done over 40 passes with shifting into 6th gear with nil issues. The A10 drives and shifts as nice as it does driving to the track as it does driving home after a full day of racing with 6th gear burnouts.

3 years ago I was going to have the last pass of the day and decided I'm going to destroy my tires and went bananas in the burnout and did a 7th gear burnout and absolutely smoked the place out (see pic). Was it stupid for me to do that? Absolutely, Did the track officials tell me off? They sure did but man was it fun and I had a smile on my face all the way on the drive home!

[2023_ZL1-AUTO]

Not sure this matters to anything in this post. But I stumbled across this via the HPTuners knowledge base:

Force Motor
These values are the calibration of the transmission force motor (pressure control solenoid) versus desired line pressure and transmission temperature. The force motor is a relief valve that requires a current to reduce line pressure, the higher the current the lower the resulting line pressure. It is not recommended to change these values unless you have modified the transmission pressure control solenoid or are experiencing trans slip under heavy load. If you increase the Max Line Pressure constant, you may have to set the values in the 100 column to match (or be slightly lower) than the 96 column. Certain calibrations have to 100 column set to 1245ma (full line pressure bleed off).

• Force Motor Current vs. Commanded Line Pressure vs. Temp - Positive: This table determines how much current is applied to achieve the desired line pressure in relation to transmission temperature.
• Force Motor Current vs. Commanded Line Pressure vs. Temp - Negative: This table determines how much current is applied to achieve the desired line pressure in relation to transmission temperature.

Desired Shift Time
This is the desired shift time for each part throttle shift.

• Desired Shift Time vs. Torque - Normal: Normal Mode desired shift time (secs)
• Desired Shift Time - Normal: Normal Mode desired shift time
• Desired Shift Time Adder- Normal: Normal Mode desired shift time adder
• Desired Shift Time vs. Torque - Performance: Performance Mode desired shift time (secs)
• Desired Shift Time - Performance: Performance(Tow/Haul) Mode desired shift time
• Desired Shift Time Adder- Performance: Performance Mode(Tow/Haul) desired shift time adder

TUTD

• TUTD Mode Select: Enable/disable TUTD feature.
• TUTD Type: Selects the method used to wire the TUTD switch
• TUTD IP Display: Enable/disable the TUTD mode display
• TUTD UpDown Enable Req: Enable/disable the requirement for an up/down request and a mode request to enable TUTD
• TUTD Hold Shift Enable: Enable/disable a shift to occur if the driver is holding down the TUTD switch
• TUTD Mountain Mode: Enable/disable powertrain braking the TUTD downshifts, when in D3
• TUTD Range Select: Enable range select TUTD mode activation, otherwise use state of TUTD switch
• TUTD Range Select Gear: When range select TUTD mode is enabled this selector position enables TUTD mode

Shift Pressure
These tables define the desired transmission line pressure in relation to input torque and current gear. These tables are used to modify your transmission shift pressures.

• Base Shift Pressure vs. Torque vs. Gear - Normal: Normal Mode Desired Shift pressure. Table returns the pressure offset to be used on the Force Motor Current table axis. Increasing these values firms the shift. Value range is from 0 to 96
• Base Shift Pressure vs. Torque vs. Gear - Performance: Performance Mode Desired Shift pressure. Table returns the pressure offset to be used on the Force Motor Current table axis. Increasing these values firms the shift. Value range is from 0 to 96
• Brake Shift Pressure vs. Torque vs. Gear: During a manual downshift using the gear selector, this alternate table is used to modify the line pressure. If this table is not in use, the Engine Braking downshift will be taken from the base shift pressure table(s). Table returns the pressure offset to be used on the Force Motor Current table axis. Increasing these values firms the manual downshift.
• Max Line Pressure: This is the maximum desired line pressure allowed. It is a clamp for any shift table value and has the final say on the line pressure offset before it is used on the Force Motor Current table.

Shift Pressure Modifier

• Upshift and Downshift Pressure Modifier: These tables are a modifier to the returned base shift pressure tables. It increases/decreases the pressure by adding positive or negative pressure depending on torque and trans temperature. Increasing these with a positive values firm the shift. Zero has no effect.
• Upshift Pressure Modifier Mult vs. Temp vs. Gear: An optional table multiplier to the returned base shift pressure tables. It increases/decreases the pressure depending on shift and trans temperature. Increasing the multiplier firm the shift. 1= no change.

Shift Pressure Adapt

• Upshift Adapt: Master enable/disable for upshift pressure adapt
• Downshift Adapt: Master enable/disable for WOT(detent) downshift pressure adapt

Oncoming Pressure Preset

• Oncoming 2nd: Base Preset(TAP) Oncoming clutch pressure for 1-2 shift
• Oncoming 3rd: Base Preset(TAP) Oncoming clutch pressure for 2-3 shift
• Oncoming 4th: Base Preset(TAP) Oncoming clutch pressure for 3-4 shift
• Oncoming 5th: Base Preset(TAP) Oncoming clutch pressure for 4-5 shift
• Oncoming 6th: Base Preset(TAP) Oncoming clutch pressure for 5-6 shift

Offgoing Pressure Preset

• Offgoing 2nd: Base Preset(TAP) Offgoing clutch pressure for 1-2 shift
• Offgoing 3rd: Base Preset(TAP) Offgoing clutch pressure for 2-3 shift
• Offgoing 4th: Base Preset(TAP) Offgoing clutch pressure for 3-4 shift
• Offgoing 5th: Base Preset(TAP) Offgoing clutch pressure for 4-5 shift
• Offgoing 6th: Base Preset(TAP) Offgoing clutch pressure for 5-6 shift

Clutch Volume Preset

• Shift Clutch Volume Preset - 2nd: Base Preset(TAV) clutch volume for 1-2 shift
• Shift Clutch Volume Preset - 3rd: Base Preset(TAV) clutch volume for 2-3 shift
• Shift Clutch Volume Preset - 4th: Base Preset(TAV) clutch volume for 3-4 shift
• Shift Clutch Volume Preset - 5th: Base Preset(TAV) clutch volume for 4-5 shift
• Shift Clutch Volume Preset - 6th: Base Preset(TAV) clutch volume for 5-6 shift