BNRacing
Supporting Vendor
NO LIFT SHIFT - Works! We can add this to the Cruze and the Sonic via the tune!
Background: One of the performance killers on the 1.4 turbo / manual transmission car is the fact the car dumps the boost during shifts. This is "by design" as when the accelerated is released for a shift, the throttle closes, which requires "blowing off" the boost to avoid compressor surge.
When I was performance testing my Cruze vs. Sonic last month, I found quite a difference in the 0-60 MPH times I was able to achieve. My automatic Cruze got a best of 6.8s whereas my manual (and lighter) Sonic was only able to muster a 7.2s, and most tests were around 7.5s. After testing the Sonic it became immediately apparent the boost dump during shifts was hurting the performance.
To deal with this issue on the turbo Cobalt SS / HHR SS, GM added a "no lift shift" feature from the factory. You can keep your foot to the floor when you shift gears, and the ECM won't dump the boost.
The controller used in the Cruze / Sonic also supports this but it is disabled from the factory. I was able to re-enable it. I haven't done any new 0-60 testing, but I'm not sure it will be a whole lot better (more on this below). On 2-3 shift, though, there is zero boost drop.
Throughout my testing today I noticed something else, though - even if you disable stabilitrac and traction control, the ECM will still cut power if it detects wheelspin. This is problematic because this also causes a boost dump, and I was getting wheelspin issues on the 1-2 shift while no lift shifting (it begs the question why even have a traction control disable feature if, even when disabled it will still disallow wheelspin).
The next challenge will be to figure out if we can find a way to disable the wheelspin traction control feature, which is really necessary if we want to make bigger improvements in 0-60 times with the manual transmission vehicles.
Here is an example of no lift shift on ZZPs cobalt ss, it would work the same way-
ZZP Turbo Swap LNF Dyno - YouTube
NO loss of boost between gears!
Background: One of the performance killers on the 1.4 turbo / manual transmission car is the fact the car dumps the boost during shifts. This is "by design" as when the accelerated is released for a shift, the throttle closes, which requires "blowing off" the boost to avoid compressor surge.
When I was performance testing my Cruze vs. Sonic last month, I found quite a difference in the 0-60 MPH times I was able to achieve. My automatic Cruze got a best of 6.8s whereas my manual (and lighter) Sonic was only able to muster a 7.2s, and most tests were around 7.5s. After testing the Sonic it became immediately apparent the boost dump during shifts was hurting the performance.
To deal with this issue on the turbo Cobalt SS / HHR SS, GM added a "no lift shift" feature from the factory. You can keep your foot to the floor when you shift gears, and the ECM won't dump the boost.
The controller used in the Cruze / Sonic also supports this but it is disabled from the factory. I was able to re-enable it. I haven't done any new 0-60 testing, but I'm not sure it will be a whole lot better (more on this below). On 2-3 shift, though, there is zero boost drop.
Throughout my testing today I noticed something else, though - even if you disable stabilitrac and traction control, the ECM will still cut power if it detects wheelspin. This is problematic because this also causes a boost dump, and I was getting wheelspin issues on the 1-2 shift while no lift shifting (it begs the question why even have a traction control disable feature if, even when disabled it will still disallow wheelspin).
The next challenge will be to figure out if we can find a way to disable the wheelspin traction control feature, which is really necessary if we want to make bigger improvements in 0-60 times with the manual transmission vehicles.
Here is an example of no lift shift on ZZPs cobalt ss, it would work the same way-
ZZP Turbo Swap LNF Dyno - YouTube
NO loss of boost between gears!
