[ANSWERED] How Does No-Lift-Shift Work
10-02-2015, 03:24 PM
#1
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[ANSWERED] How Does No-Lift-Shift Work
Original question is here.
BJ67 asked:
Exactly how does NLS work and exactly what mode do you have to be in? and what other settings are required. Also does rev match have to be on or off or does the system work the same regardless of rev match. Non z51 base car. I know how to power shift but the technical details are important.
Exactly how does NLS work and exactly what mode do you have to be in? and what other settings are required. Also does rev match have to be on or off or does the system work the same regardless of rev match. Non z51 base car. I know how to power shift but the technical details are important.
Tadge answered:
No Lift Shift (NLS) works in all driver modes and with rev match on or off. In other words, all the time. Many manufacturers seek to reduce the stress in their drivelines by sensing the conditions for a power shift and close the throttle regardless of what the driver is doing with the throttle pedal. The problem with closing the throttle is that when the next gear is selected and the clutch is re-engaged, the intake manifold has very low pressure. The throttle then has to re-open to fill it and feed the cylinders. Although this all happens very quickly, there is a delay for the engine to back up to full torque (and these effects are magnified in charged engines where intake manifold pressures are higher). Although I can't share the calibration details, the NLS algorithm looks for the conditions where the driver is requesting maximum performance and, within certain bounds, keeps the throttle fully open during the shift to keep the manifold pressure relatively high. In this way the engine is ready to provide full torque upon completion of the shift. The performance difference is easily measured in our straight line acceleration testing. And of course the Corvette is designed for and fully validated for this usage.
No Lift Shift (NLS) works in all driver modes and with rev match on or off. In other words, all the time. Many manufacturers seek to reduce the stress in their drivelines by sensing the conditions for a power shift and close the throttle regardless of what the driver is doing with the throttle pedal. The problem with closing the throttle is that when the next gear is selected and the clutch is re-engaged, the intake manifold has very low pressure. The throttle then has to re-open to fill it and feed the cylinders. Although this all happens very quickly, there is a delay for the engine to back up to full torque (and these effects are magnified in charged engines where intake manifold pressures are higher). Although I can't share the calibration details, the NLS algorithm looks for the conditions where the driver is requesting maximum performance and, within certain bounds, keeps the throttle fully open during the shift to keep the manifold pressure relatively high. In this way the engine is ready to provide full torque upon completion of the shift. The performance difference is easily measured in our straight line acceleration testing. And of course the Corvette is designed for and fully validated for this usage.
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10-04-2015, 10:45 AM
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10-04-2015, 11:05 AM
#6
Melting Slicks
launch control has nothing to do with NLS on the C7. I also believe launch control does not have to used or activated for NLS on the Camaro, Cadillac or the later C6 cars.
10-04-2015, 11:07 AM
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The NLS system in the later C6 cars is different than what's in the Caddies and Camaro. It requires you to use launch control, and is not on otherwise. I can assure of that fact.
10-04-2015, 02:29 PM
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Do you have any idea what GM uses to control RPM during a NLS? If it's keeping the throttle wide open, then it has to be either spark or fuel. Since stock cars use fuel-cut as the default for the rev limiter, that would be my guess. More info would be cool, though.
10-06-2015, 08:31 PM
#10
Melting Slicks
when you initiate a no lift shift , foot on the floor and keep it there, do your shift as close to 6500 as you can with out hitting the rev limiter first. If for instance you initiated your 1-2 shift at 6400 rpm, the NLS feature keeps the rpm at 6400 during that split second foot to the floor blip the clutch and shift all at the same time technique. The feature holds the rpm you initiate the shift for a very short time. If you are slow doing the power shift or screw up, the system just lets the engine hit the rev limiter which is 6600 rpm if you are slow to lift of the throttle.
10-06-2015, 08:38 PM
#11
Melting Slicks
Yes, gas pedal right on the floor, slight pressure on the shifter, blip clutch and shift at the same exact time at your desired rpm. Hard part is to train yourself not to lift.The other hard part is shifting quick enough or early enough to not hit the rev limiter (fuel shut off)
10-07-2015, 02:15 PM
#12
Safety Car
I thought about NLS when doing the Mojave Magnum 1.5 mile run. I couldn't fight my instinct to let of the gas. Decades of driving manual says it's all wrong!
Great question and great response.
Thank you Tadge!
Great question and great response.
Thank you Tadge!
10-07-2015, 08:06 PM
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St. Jude Donor '15
When I do the NLS I start the action at 5800 rpms, peak hp. also gives a bit of room for a screw up...haven't had that problem yet but you never know.
Mt '09 was not fun to do the NLS in as it dogged going into the next gear, was better dong speed shifts.
Mt '09 was not fun to do the NLS in as it dogged going into the next gear, was better dong speed shifts.
10-07-2015, 08:20 PM
#16
Melting Slicks
Initiate the power shift at 6200, you shouldn't hit the rev limiter. The No lift shift starts to work when you move the shift lever. If you push the clutch in before you pull or push the shift lever it will go right to redline and hit the rev limiter.
10-07-2015, 08:28 PM
#17
Melting Slicks
You are leaving some power on the table if you actually shift all three shifts at say 6000. I am thinking the engine rpm increases 200 rpm for the delay it takes from reading the tach and initiating the shift. So making shifts at 6000 rather than closer to 6500, you could be a tenth or 2 off in a 1/4 mile timed track and your trap speed will be a little slower.
10-07-2015, 08:34 PM
#18
Melting Slicks
Do not know if it existed in 08, and not sure what year the naturally aspirated vettes got it.
