12.54@111 no cool down...bone stock automatic

[a_Username]

Originally Posted by RoketRdr

It's not not specifically directed at "heat soak". There are a number of parameters that will cause the ECM to instruct the TCM to change the shifts points. Heat soak conditions would be one of them. Its common practice by all manufacturers to not only protect the drive train from immediate damage and failure but to also reduce the possibility of paying on warranty issues down the road. It has been proven in the diesel community that this was being done and steps had to be taken to work around it. You can read about 'limp mode' in your owners manual to give you an idea of what will happen if you push the vehicle to set certain codes or exceed certain parameters. GM doesn't hide this info and makes it known. But before you get to a 'limp mode' or 'limp home' condition the ECM will do whats necessary to try and stop the damage such as changing the shift patterns and reduce power output. i.e...remove timing, short shift, cut fuel injection rates, torque management, etc. In the Duramax if you push beyond certain parameters which cause high transmission slippage it will automatically downshift and lock you into 3 gear and wont allow a speed above 60mph no matter what the throttle position is. Computer controlled cars and trucks are programmed to protect the drive train and the manufacturer and that's why tuners have had to overcome the existing fail-safe systems from the factory's. So no it's not speculation. To what extent the ZL1's ECM is controlling the TCM and shift points will have to be determined by one of the tuners who have looked at both of the tunes and addressed the issue.

This can't be limp mode. Every time I've seen someone in a Duramax go into limp mode, then he can't shift out of 4th gear. IIRC, it doesn't limit RPMs , but it does limit torque. Plus, the ECM is only causing it to shift 300-500 RPMs lower, so I'm not sure how that protects much of anything.

[RoketRdr]

Originally Posted by a_Username

This can't be limp mode. Every time I've seen someone in a Duramax go into limp mode, then he can't shift out of 4th gear. IIRC, it doesn't limit RPMs , but it does limit torque. Plus, the ECM is only causing it to shift 300-500 RPMs lower, so I'm not sure how that protects much of anything.

I never said his car went into limp mode. I was explaining to the other gentlemen about how the safety barriers programmed into the vehicle work. I've limped a Duramax more times than I could count while we were trying to sort out issues in my first truck (2001) and it will force a downshift and lock into either 4th or 3rd depending on the wheel speed and engine load percentage, the RPM'S were limited no matter what the throttle position was and of course torque management goes into full protection mode.
If the TCM see's an issue with the tranny it will keep you from hitting red line and causing further damage or complete tranny failure. The ECM can also limit RPM's to maintain traction at full throttle which is partially what the PTM and traction control are for as well as the torque management tables. There are many other reasons an ECM will limit RPM's but that can be for another thread and proper topic.

[a_Username]

Originally Posted by RoketRdr

I never said his car went into limp mode. I was explaining to the other gentlemen about how the safety barriers programmed into the vehicle work.

It sure seemed like you were implying such a thing.

I've limped a Duramax more times than I could count while we were trying to sort out issues in my first truck (2001) and it will force a downshift and lock into either 4th or 3rd depending on the wheel speed and engine load percentage, the RPM'S were limited no matter what the throttle position was and of course torque management goes into full protection mode.

It may be different on the newer models, considering I watched a good friend ride home an hour plus in limp mode in his '07 and a half. Obviously when he drove up to red lights, he had to get on it to go anywhere, which is why I'm assuming his RPMs weren't limited. Plus, I know he was revving it pretty high, considering he was smoking like a freight train at take off.

If the TCM see's an issue with the tranny it will keep you from hitting red line and causing further damage or complete tranny failure. The ECM can also limit RPM's to maintain traction at full throttle which is partially what the PTM and traction control are for as well as the torque management tables. There are many other reasons an ECM will limit RPM's but that can be for another thread and proper topic.

There wouldn't be traction issues in 2-3 gear going down the track at 80 MPH, so that doesn't explain why the ECM would try to lower shift points in those gears. Again, how much help is it lowering 500 RPMs? 5500 RPM is still a lot of stress on the drivetrain.

[RoketRdr]

Originally Posted by a_Username

It sure seemed like you were implying such a thing.



It may be different on the newer models, considering I watched a good friend ride home an hour plus in limp mode in his '07 and a half. Obviously when he drove up to red lights, he had to get on it to go anywhere, which is why I'm assuming his RPMs weren't limited. Plus, I know he was revving it pretty high, considering he was smoking like a freight train at take off.



There wouldn't be traction issues in 2-3 gear going down the track at 80 MPH, so that doesn't explain why the ECM would try to lower shift points in those gears. Again, how much help is it lowering 500 RPMs? 5500 RPM is still a lot of stress on the drivetrain.

I didn't imply anything. You read what you wanted to. Go back and read again to see what I was explaining to the gentleman that didn't understand the programming and fail-safes in the car.

If he had shut the truck off for 5 minutes the limp-mode would reset and it would be back to normal driving until he over stressed the tranny clutches again. He may have been revving high but it was still limited and not allowed to tach out. It would defeat the purpose of a "limp home" mode to protect the tranny if you were allowed to red line the tach and continue beating up the clutches that are fried.

580hp can break traction at full throttle shifting into any gear at any speed. If they weren't concerned about that there would be no traction control or PTM system. The PTM system is designed to protect an inexperienced driver from making a huge mistake until he/she learns how to use safely use the power of the car. It will pull timing or induce torque management to keep the car under control during full throttle shifts as well as short shift the tranny to ensure that traction is maintained. The gear and speed aren't the issue. Full throttle with 580hp - 556 lb/ft is.

[HeavyH20]

This experience sounds very familiar. When I first got my CTS-V, I was completely underwhelmed with a 12.6@111 MPH on my first time out. Sure, it was hot (90's) and the DA was 4600, but still. After digging a bit, and checking things out, I found that the boost bypass was actually not 100% closed so it was bleeding boost. Once I addressed that, it acted a bit more normally with a 12.3@117 MPH in the heat (80's, 3500 DA) and as a final run, before I did the intake, pulley and tune, I did squeeze out an 11.97 @119 MPH (60's 1800 DA). My car now does 11.2@125 MPH with some minor bolt ons. I fully expect the ZL1 to do the same or a bit better thanks to some of the optimizations.

Check your boost bypass valve and make sure the back off is not too far forward opening the valve.

[speedmon]

Originally Posted by HeavyH20

My car now does 11.2@125 MPH with some minor bolt ons. I fully expect the ZL1 to do the same or a bit better thanks to some of the optimizations.

minor bolt ons? Care to share what those minor bolt-ons might be? Just
intake, pulley and tune?
Its the same powerplant. Minor bolt on to me is a 20 minute CAI.

I'd like to see someone just a do a pulley, a ZR1 camshaft and a tune...simple

[DanSS24]

What was this thread about again...Oh yeah, OP ran 12.54 bone stock. Good run on road course car. I'm sure your times will get better as time goes on. When I first got my SS back in 1998, my very first run was 13.99. By the end of the night, I was running low 13's bone stock. I ended up building up my suspension for SCCA and regular street duty, and loved the way it turned out. What you got there is a beast for the road course, which it was actually built for, but can also run on the track. However, Chevy built a track car...COPO car. They built a road course car...the 1LE...waiting for that to happen. And so what you got there is the best of both worlds, a "technology advanched" vehicle that neither Ford or Dodge can match.

Yet.

[Bob Cosby]

Originally Posted by RoketRdr

...I was explaining to the gentleman that didn't understand the programming and fail-safes in the car....

Please be advised that "understanding" is not at all the issue. However, because of where we are, I'll leave it at that.

Good day. Its hot out, so don't go drag racing....but road racing shouldn't be a problem...

Bob

[white ZL1]

I'm dying to see a bin file pulled from a ZL1 so we can see all of this heatsoak and protection programming built in.
Better yet, how about a few datalogs of passes?

[Bob Cosby]

Originally Posted by white 2SS/RS

I'm dying to see a bin file pulled from a ZL1 so we can see all of this heatsoak and protection programming built in.
Better yet, how about a few datalogs of passes?

Indeed!

[SGOS252382]

Originally Posted by DanSS24

What was this thread about again...Oh yeah, OP ran 12.54 bone stock. Good run on road course car. I'm sure your times will get better as time goes on. When I first got my SS back in 1998, my very first run was 13.99. By the end of the night, I was running low 13's bone stock. I ended up building up my suspension for SCCA and regular street duty, and loved the way it turned out. What you got there is a beast for the road course, which it was actually built for, but can also run on the track. However, Chevy built a track car...COPO car. They built a road course car...the 1LE...waiting for that to happen. And so what you got there is the best of both worlds, a "technology advanched" vehicle that neither Ford or Dodge can match.

Yet.

12.54 isn't all that bad. It's the 111 mph trap speed that's a concern. A 580hp car shouldn't be trapping 111 mph unless there's some sort of issue.

That trap speed is a good indicator of HP. 111 mph traps is what a car making 100hp less than the ZL1 should be trapping in those conditions.

[Pro Stock John]

Did OP post where he raced, time, maybe we can figure out the DA. If I was OP I'd run again, keep working on it. Experiment with the car.

[capnkirk52]

Originally Posted by DanSS24

And so what you got there is the best of both worlds, a "technology advanched" vehicle that neither Ford or Dodge can match.

What is so technology advanched on the ZL-1? MR? Personally, I'd rather go 10mph faster in the 1/4, have an 8 inch touch screen with sync, launch control that actually works and get 30% better fuel economy than have MR.

Just me I guess.

[white ZL1]

Originally Posted by Pro Stock John

Did OP post where he raced, time, maybe we can figure out the DA. If I was OP I'd run again, keep working on it. Experiment with the car.

He said 1950 DA in the first post, but didn't say where and when the pass was made. If that DA is correct, it isn't what killed the mph.

I'm leaning towards something mechanical as HeavyH20 implied.