[Mr. Wyndham]

Originally Posted by travislambert

Hey Al,

Can you talk to us about the details of launch control and share any tips for effectively launching the 6th Gen ZL1 with a manual transmission?

For those of us with a custom launch control configuration, we can choose a slip target between 5% and 15%. When the car first begins to launch the front wheel-speed is near zero, so any slip of the rear tires will exceed the 15%. How was the car designed to react in this scenario? If there is some mechanism to conditionally apply the slip target as the car begins to move, can you share the details of this mechanism? Are there any factors, such as tire wear, wheel-speed sensor accuracy, sensor latency, etc. that may significantly impact the wheel slip % calculation at very low speeds?

Al's Answer:

The 5-15% was simply the range selected by the Camaro team. You are 100% correct, any rear wheel slip from 0 speed would result in a wheel slip percent much greater than 15%. In fact, we could have just offered different levels of launch control numbered 1-20 and it would have done the same thing. Essentially 10% is where we normally tune launch control, and any move from 10% is just a scalar changing the slip profile. None of the factors mentioned (tire wear, etc) will affect the wheel slip % calculation, as it is merely parameter setting, not real-time compensation. Likewise, we cannot control how the driver releases the clutch, but we will protect the engine, transmission and clutch as a result of their driver action.

The custom launch control is best explained with a drawing:

The red line below is the target slip the system will control to. Then the 'modified' targets from 15% and 5% are shown.

Originally Posted by travislambert

What effect does each PTM Mode/Surface Type configuration have on the launch control?

Al's Answer:

PTM 1-4 is tuned for 'street surfaces' (unprepped). PTM5 is for drag strip 'high traction'. There is a noticeable difference between these two settings.

Originally Posted by travislambert

With high-traction surfaces many owners have experienced what’s being described as “bogging” while launching. Can you help us to better understand how the torque management systems are applied during launch to reduce as well as reintroduce power (assuming wheel-slip/traction is not an issue)?

Al's Answer:

With respect to “bogging” on high traction surfaces, due to the stickiness of the tires and the tall first gear ratio, we drag the engine down once clutch is fully engaged. Currently we only use throttle and spark during pre-launch phase to control to requested engine speed which limits how quickly we can recover boost. We understand that a particular launch may result in a “bogging” condition, but much of that can be eliminated by practicing different styles of clutch ‘dumping’. See the answer below on how we achieve our quarter mile times to see the effects of different launch styles. One thing to note, that may not be obvious to the customer, is that the clutch release is still fairly quick - too slow of a clutch release will result in exiting of launch control and the engine reducing torque for clutch protection.

Originally Posted by travislambert

Can you share with us how the advertised quarter-mile times are determined? According to our “Official 6th Gen 1/4 Mile V8 Fast List”, only one member has been able to achieve the advertised 11.8 second quarter-mile time for the ’17 ZL1 M6 coupe, but many members have far exceeded the 11.4 advertised for the ’17 ZL1 A10 coupe.

Al's Answer:
The advertised 0-60 and quarter mile times are determined by testing all available vehicles built with production intent hardware and calibrations throughout the development of the Camaro. As we get closer to production, and improvements are made, we will do our final measurements just prior to our press release. This is why you will never see early postings of our performance times, because we will push to the very end to get the fastest times possible. We also determine an average using multiple drivers and vehicles. The process starts by inspecting the vehicle for production intent calibrations, placard tire pressures, and recommended fuel type (Premium for ZL1).

Our testing takes place on an unprepped surface straightaway at the Milford proving grounds. It is the preferred location due to length of track and similar characteristics to magazine tests. If timing/weather are a factor, we will use our Yuma proving grounds.

The process starts with a few burnouts to warm up the tires (being careful not to overheat), followed by multiple quarter mile “runs”, two in each direction, multiple times. For the ZL1 manual on an unprepped surface, traction off (one button press) was found to be the fastest, however launch control is the easiest way to be consistent because you go to 100% throttle, let off the clutch, and let the car manage torque for you.

After testing, each session is analyzed and a time for that session is determined. The data is adjusted for ambient conditions and then the averaging of four runs, two in each direction, determines the session results.

Each published specification is the average of multiple sessions to eliminate any flyers that would be unattainable. The ZL1 Manual required significant practice of clutch pedal and throttle pedal application due to the tall first gear and the high grip tires. We experienced situations where the tires would light up with too much throttle and a slow clutch release, or grip too much with too quick of a clutch dump and not enough or too slow throttle, while we learned to maintain the right amount of stick/slip for best times. Also, shifting before 60 is worth about .2 seconds on the 0-60 time but does not impact ¼ mile. Don’t forget, the ZL1 will do 0-63 mph in first gear, to give you those 0.2 seconds back if you are just doing 0-60’s.

As we mentioned in the last question, the clutch release is still fairly quick, too slow of a clutch release will result in exiting of launch control and the engine reducing torque for clutch protection

The chart below shows the raw data of one of the better launches, including engine RPM.



The bottom line is this – We publish numbers that we feel confident are attainable (with practice) by our customers, and because we take a “best average”, we know many will also exceed our results. A driver also needs to understand how to properly use the clutch, to avoid the protection software intervening to protect the engine, transmission and clutch. These ‘nannies’ will often slow down a quarter mile time, which could be the nature of many not being able to achieve our times. My advice is to have a great time trying to learn your Camaro, because it is an awesome car, and will perform for you.