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To add my two cents, I'm more in the "break it while it's under warranty" category. Otherwise, you're just creating an expense down the road after three years of keeping the car tucked away in the garage aside from a few leisurely parade laps during lunch.
And yeah, I agree, debated for years. In the end, it's just a car. I'll likely take it to the automatic car wash if it's too cold to wash it in the driveway anyway.
Good news is warranty extends long after the 1500 mile mark. Proper break in allows the powertrain to last beyond the warranty period.
I toured the plant as well. In fact had a private full tour with my Director of National Accounts! It was he or me that would start the car at the end of the line! Since I had a Corvette picked myself! I was the one who started it for the first time when it was ready to come off the line. NFW do they run it anywhere max power! Sure part of the test includes running it through the gears, can see that on a number of video's. I was answering the statement that it isn't stressed more in Launch Mode than experienced at the factory!! That is BS.
SIDEBAR (The highest stressed Engine part are Valve springs. Worse at High RPM)
This is the reason when I was breaking in my engine I was carful to have the valve springs treated very carefully for 500 miles. As would GM! Especially as my September 2020 C8 was in a time span when some valves were breaking usually under 500 miles. They are the most highly stressed engine part AND at high rpm the harmonics cause increased loads.
Quoting: The valve spring is the most highly stressed engine part. Just how much torture are we looking at? To put things in perspective, Lunati manufactures high-tech connecting rods with a 250,000-psi tensile strength. The rod "rarely sees even 50,000 psi of stress under real-world operating conditions" (20 percent of its rated load, or a 4:1 safety margin). But it's common for a valve spring to continually operate at half or slightly more than half of its rated load. "A spring that's rated at 300,000 psi routinely will see loads approaching 150,000 to 190,000 psi every cycle. Nothing else in the motor continuously runs at 50 percent of its ultimate strength—and it needs to do that, in long-distance racing, for millions of cycles." That's not even a 2:1 safety margin—so, yes, valve springs really do operate right on the edge in a high-end motor!
Break-in New Valve Springs: It’s important for new valve springs to be broken in properly. Upon initial start-up limit the rpm to 1500 to 2000 rpm until operating temps are reached, Then shut off the engine and allows to cool to room temperature. This will usually eliminate early breakage and prolong spring life.
Note the Extra Spring Movement as RPM Increases. Causes Higher Stress Valve Float - YouTube
Good info Jerry,
It never ceases to amaze me when I see someone start their sports car and the first thing they do is start REVVING the engine. VROOM!!!! VROOM!!!! VROOM!!!!
That's nice. What I do though is start the vehicle and then let it idle while it gets up to operating temperatures first. On the C8, I usually remote start the vehicle every single time.
When walking to my car in the parking lot, it is already running before I reach the car.
At home, I just open the garage (because I don't like carbon monoxide) and hit the start button. I have actually thought about figuring out a way to have my garage door open automatically for me.
I have a nice Z-wave based home automation system using an Aeotec Z-Stick connected to a hypervisor host running an OpenHAB3 virtual machine. I could probably find some sort of environmental trigger, audio level from exhaust note, or whatever to trigger an event to control the contact input to the garage door opener. (or I could just walk over and press the garage door remote, but that isn't nearly as much fun...)
GM says it's fine to floor the car from a standing start, and run it to redline in first gear, at 501 miles. Launch control starts at about 3,000 rpm, and feathers the clutch to minimize wheelspin. It's not like side-stepping the clutch in a manual transmission car. I can't imagine LC is any worse than just stomping on the loud pedal yourself.
Nonetheless, I didn't try it out until well past 1500 miles anyway. Better safe than sorry.
GM says it's fine to floor the car from a standing start, and run it to redline in first gear, at 501 miles. Launch control starts at about 3,000 rpm, and feathers the clutch to minimize wheelspin. It's not like side-stepping the clutch in a manual transmission car. I can't imagine LC is any worse than just stomping on the loud pedal yourself.
Nonetheless, I didn't try it out until well past 1500 miles anyway. Better safe than sorry.
It’s still essentially dumping the clutch like in a manual. You’re dumping about 425 ft-lbs of torque into the drivetrain all at once in launch control. Stomping on the pedal from a dead stop is much easier on the drivetrain because load is gradually applied.
Think of it like setting an anvil on a table verses dropping it from 100 feet.
It’s still essentially dumping the clutch like in a manual. You’re dumping about 425 ft-lbs of torque into the drivetrain all at once in launch control.
No you're not, the slipping of the clutches is feeding in as much as the tires can handle. If you've ever side stepped a clutch, you'd know the difference. In fact until a couple months ago the fastest launch I had done was a 2.7 WITHOUT using launch control. I have since shown one at 2.6 with launch control. Until that one I had never had a pass as quick with it.
Last edited by Phil1098; Jan 26, 2022 at 02:40 PM.
^^^
Yep, like my 1st car, a '41 Ford Coupe with an 1/8 inch bored Olds. Side step the clutch and you'd light up those skinny tires we had in 1960 until you lifted! Had to slip the clutch and as you say feel what it took to minimize wheel spin.
Like the Beach Boys Song, "Shut Down:" To get the traction I'm ridin' the clutch. My pressure plate's burnin' that machine's too much!
And that LT2 engine torque gets multiplied by the 1st gear ratio in 1st coming off the line! Here is an estimate! Just took a SWAG at 80%
No you're not, the slipping of the clutches is feeding in as much as the tires can handle. If you've ever side stepped a clutch, you'd know the difference. In fact until a couple months ago the fastest launch I had done was a 2.7 WITHOUT using launch control. I have since shown one at 2.6 with launch control. Until that one I had never had a pass as quick with it.
Launch control isn’t dropping it at max rpm, it’s holding at about 3k (probably because max rpm would just roast the tires). If it just roasted the clutches then you wouldn’t be getting 2.6 second 0-60’s either.
Launch control isn’t dropping it at max rpm, it’s holding at about 3k (probably because max rpm would just roast the tires). If it just roasted the clutches then you wouldn’t be getting 2.6 second 0-60’s either.
It isn't dropping it at all. Again, it's just another WOT start. Why would GM say NO WOT starts before 500 if a WOT start DIDN'T have the potential of damage?
It isn't dropping it at all. Again, it's just another WOT start. Why would GM say NO WOT starts before 500 if a WOT start DIDN'T have the potential of damage?
WOT is when the clutch is already engaged and you just shove the throttle to the floor. A launch is when the clutch drops and connects your 3000 rpm engine to your 0 rpm wheels.
WOT is when the clutch is already engaged and you just shove the throttle to the floor. A launch is when the clutch drops and connects your 3000 rpm engine to your 0 rpm wheels.
Why do you not get it, it is NOT DROPPING the clutch, they are slipping and being fed to the wheels. Explain the load difference on the drivetrain when I do a 2.7 with launch control and when I do a 2.7 without launch control.
It’s still essentially dumping the clutch like in a manual. You’re dumping about 425 ft-lbs of torque into the drivetrain all at once in launch control. Stomping on the pedal from a dead stop is much easier on the drivetrain because load is gradually applied.
Think of it like setting an anvil on a table verses dropping it from 100 feet.
No, you're really not. If you dumped all the torque instantly, the rear tires would break loose. Launch control modulates the throttle and clutches to prevent wheelspin, and that limits the amount of torque hitting the transmission independently. It's easy enough to prove. Just stomp on the throttle from a standing start and compare it to launch control The first clearly puts more power into the tires instantly than the second.
Why do you not get it, it is NOT DROPPING the clutch, they are slipping and being fed to the wheels. Explain the load difference on the drivetrain when I do a 2.7 with launch control and when I do a 2.7 without launch control.
LC also doesn't give 100% throttle instantly. As you noted before, the computer is controlling both throttle and clutch slip to prevent wheelspin. No one who has ever sidestepped the clutch on a real manual would think they're the same.
LC also doesn't give 100% throttle instantly. As you noted before, the computer is controlling both throttle and clutch slip to prevent wheelspin. No one who has ever sidestepped the clutch on a real manual would think they're the same.
Exactly, and if you really want to throw a shock at the drivetrain, use burnout mode. THAT is a clutch dump going to huge sticky tires with over 2,000 pounds of weight on them in an instantaneous spike to break the tires loose and keep them spinning. LC is nothing to that by comparison. In fact if I modulate the throttle and brake (like I did on my 2.7 without LC) I did exactly the same as the computer did to get the same 2.7 with LC. Like I said, LC is nothing more than a WOT start that IS allowed after 500 miles. Even Tadge said "I would try to be patient for 1,000 miles" Funny he never said "whatever you do, don't get on it for 1,500 miles".
Why do you not get it, it is NOT DROPPING the clutch, they are slipping and being fed to the wheels. Explain the load difference on the drivetrain when I do a 2.7 with launch control and when I do a 2.7 without launch control.
In order for your car to move, the load had to quickly get transferred to the wheels. If you just dump the clutch, you just spin wheels and nothing moves. If you just slip the clutch, you still don’t move. The only way to get a good 60 foot time is to quickly transfer the power from the engine to the wheels which requires an impact load. Launch control may do it more gently than some guy dropping the clutch in a manual while bouncing off the rev limiter but it’s still not nothing.
Exactly, and if you really want to throw a shock at the drivetrain, use burnout mode. THAT is a clutch dump going to huge sticky tires with over 2,000 pounds of weight on them in an instantaneous spike to break the tires loose and keep them spinning. LC is nothing to that by comparison. In fact if I modulate the throttle and brake (like I did on my 2.7 without LC) I did exactly the same as the computer did to get the same 2.7 with LC. Like I said, LC is nothing more than a WOT start that IS allowed after 500 miles. Even Tadge said "I would try to be patient for 1,000 miles" Funny he never said "whatever you do, don't get on it for 1,500 miles".
Makes you wonder what’s so special about 1500 miles. They either pulled it out of their *** or did some testing to come up with that number. If they did do testing, what exactly did they test? Running the DCT at high speeds and high temps all day? Doing 100 launch control attempts?
Either way those specific details are just ground clutter at Tadge’s level. He makes the decision on going DCT or not. It’s probably the intern tasked with the break in requirements.
In order for your car to move, the load had to quickly get transferred to the wheels. If you just dump the clutch, you just spin wheels and nothing moves. If you just slip the clutch, you still don’t move. The only way to get a good 60 foot time is to quickly transfer the power from the engine to the wheels which requires an impact load. Launch control may do it more gently than some guy dropping the clutch in a manual while bouncing off the rev limiter but it’s still not nothing.
So now your story is changing and LC ISN'T dropping the clutch when earlier it was. So explain the load difference from a 2.7 without LC and a 2.7 with LC. If the car accelerated at the same rate with the same traction. How is using LC harder on it than without, all while accomplishing the same accelerative G load????? Sorry, but if I can do a 2.7 WITHOUT LC (and I have) it is exactly the same impact on the drivetrain. What you are clearly not seeing is that the car DOESN'T launch at 3,500 rpm. When you're in LC mode and the throttle is on the floor and the revs are at 3,500, the computers now have 3,500 rpms at their disposal. The computers vary throttle and clutch engagement to manage wheel spin. For anyone that actually thinks the computer doesn't vary the throttle, just put the car in weather mode and stomp it at 10 mph on a wet road, you will fall forward with the lack of acceleration.
Last edited by Phil1098; Jan 26, 2022 at 10:19 PM.
Yeah, so burnout mode is probably worse (at least as far as dumping the clutch is concerned) and I have seen a couple guys in C8's at the track snap a half shaft.
They would do a burnout first to get the tires sticky, and then once they were nice and sticky they would hit launch control and SNAP! goes the shaft.
Pretty sure that happened to that C8obsessed youtuber dude as well. Interesting that he dumped his C8 after a while, hrmm...
I was the one who started it for the first time when it was ready to come off the line. NFW do they run it anywhere max power! Sure part of the test includes running it through the gears, can see that on a number of video's. I was answering the statement that it isn't stressed more in Launch Mode than experienced at the factory!! That is BS.
