Ranger

This thread is directed to C6Z06 owners.There is a full-mooner group of C6 owners that claim TM is a myth. I am asking them to show restraint and NOT post those theories and fly-speck questions on this thread.

I had 500+ passes in C5Z06s and fairly routinely cut 1.6x 60' on DRs. This is unachievable on a stock C6Z. Here is why.

The Stock C6Z06 has a factory-set Engine Control Unit (ECU) with a feature called Torque Management (TM) that pull power (timing) on a strong launch and returns the power in increments. The purpose of TM is NOT to help launch better. It's to protect the drive train from the shock of launch and strong shift and save warranty dollars for the manufacturer.

Some owners tune out TM. I have not, as my car is stock.

I have been experimenting with various launch rpm trying to find the optimal setting for producing the lowest 330'. That means I am trying to reduce to a minimum the TM toll I must pay on launch.

So I agree that my 60' times are not optimal. But the 330' times are improving by lowering the launch rpm, not raising it. Raising the launch rpm produces a better 60' but slower 330' because of TM. To demostrate this point...Saturday on DRs, I fired off pairs of runs at four different launch rpms:

4000: Clutch pedal hung both times and I aborted the passes
3800: 11.48 11.49
3600: 11.32 11.28
3300: 11.20 11.31; on the 11.31 pass I inadvertently short-shifted the 1-2 by 300 rpms and lost nearly a tenth.

As the launch rpm is raised, the tires are not spinning differently; rather, the ECU seems to be applying a higher TM toll.

And so the learning continues.

Simplest thing to do is to tune out TM and run 10s now. But that would be too easy. I'd rather figure out a technique for doing it bone-stock, if possible.

Because of Torque Management on a stock C6Z06, switching to DRs from stock tires doesn’t change the ETs much…generally less than a tenth. They are more consistent though. Using my launch technique at a given launch rpm, my 60' will generally not vary more than .03 on DRs. More like .08 on stock tires.

My best 60' on stock tires is 1.78 and on DRs 1.73. It warrants repeating, TM is the real challenge of the car.
If there are questions, I’ll try to get to them in the next few days. Things are more hectic than usual for me right now.

Best to all,

Ranger

vette6799

Ranger, your analysis is indeed very interesting.

Do you believe as you have posted that the TM is present solely to keep warranty claims to a lower level. or is there something inherently weak in the drivetrains of our 2006 Z's that may be designed out in the future and thus allow a change in firmware, i.e. a work in progress.

It is my gut reaction, and truly speculative, that there is a design issue that GM needs to deal with. Perhaps the root of the problem is the attempt to keep vehicle weight down. I will be most interested in seeing what the 2007 Z will bring to the forefront.

Kappa

I agree with Ranger in saying that Chevy is just trying to protect themselves from warranty claims. The C6 is not the only car out there with TM. The LX cars(Charger, 300C, Magnum) have serious TM issues and TM was even apparent as far back as the '99 Grand Cherokee V8's. Almost all of the European makers have this written into the software these days too.

vettemaster1

some of my quickest launches have been from a low rpm/slip clutch a little, and quickly and smoothly depress the gas to the floor....too bad i can 't do it with any consistency....

Redline Motorsports

Ranger,

I haven't seen the parameters in the new PCM but do quite a bit of tuning with the older PCM. There are a few tables that are TM related that may be similar to this PCM. They are;

MAX torque by rpm; this one defines the maximum allowed engine torque by rpm with cars with ETC.

Abuse Mode Torque Reduction; this is the percentage of torque reduction used when in abuse mode. This one is also rpm related and increased torque reduction based on 400 rpm increments.

The problem we all have right now is there are limited parameters that we have access to with the new PCM. TM is NO mystery at all. There was a time when the 6 speed cars didn't have it and it was just the autos. I think around 2001 that started using TM in the sticks. Hacking these PCM's is a tough job and we have a lot more to learn about GM's new thought process.

As soon as EFI Live releases there new release many more tables will be available to control TM.

Nice job performing the tests!

Howard

check mate

Did you change the thermost, or air filter. What was your shift RPM's ,and were they all the same for each gear. Thank you. Good job.

Vette5.5

Seems like TM on the new Z isn't all that bad. Rangers working around it. Most tuners seem to keep some TM, preventing wheel hop drivetrain damage. These cars are balanced for the road course, with some drag strip duty thrown in for fun. Constant high RPM/high traction 1/4 mile launches can kill even the most robust purpose built(weighty) drivetrains. The new Z's power/weight ratio is quite amazing. TM helps keep it together.

Ranger

Hi check mate.

Car is bone stock; stock thermostat; stock air fliter; stock everything. On Saturday I did jerry-rig some wire to turn on the fan between passes to speed up the cool-down duration.

Target shift-point was the same for each gear...closest possible to the limiter without kissing it.

Ranger

outnumbered

Ranger,
So are you under the impression that if you have the Tm tuned out than at the degree of driving you are doing the car will most likely break?
Also thanks for the info you continue to share.
Dan

godsvette

Ranger, I just want to congraulate you on having the best et for a stock C6Z at the dragstrip. I brag on you all the time with other car euthiushaust. I appreciate how you keep your car bone stock. I love to tell people how a guy with a new Z06 goes 11.31 in the quater and 7.5 in the eigth bone stock, the reaction I get usually is wow.


Regarding TM, I wonder if it plays a part when shifting as well as launching. I believe that it is also inconsistent like sometimes it is their and sometimes it is not. I have been driving on a fairly mild evening and I tached up first gear to 7000rpm and shifted 2nd hard and the tires would'nt even break loose a bit and the coolant temp was about 190 and the oil temp was 160( the car was cooled down and I had justed started out). Their are other times with similar conditions the car goes absoultly wild when I change to 2nd. I cannot make no ryhme or reason out of it execpt that it is TM. Any comments , has anybody else experienced the same thing . Anyway, I'm going wedesday morning to have the car custom dynoed tuned and I can't wait to feel the results. (tune only)



Thanks,
Godsvette

Ranger

I still have two tenths to shed to reach the 10s bone-stock. unfortunately, TM is definitely on the critical path and needs a better approach than I've developed so far. Next time out 3100 and 2900 on DRs.

My best 60' and 330' times in a C5Z on DRs are still faster than what I've gotten so far on the C6Z on DRs even with its extra 90 rwhp. That discrepancy is the result of TM...and the clutch.

I suspect that the spec on the LS7 Clutch is also intentionally limited in the realm of clamping power. The LS6 clutch would accept a 5200 launch and pull smoothly. The LS7 clutch takes a time-out on a 4000 launch.

So by the combined effect of
(1) Torque Management
(2) the proportionately weak clamping power of the LS7 clutch and
(3) the (intentionally) weak right CV joint housing cover

Chevy seems to have engineered a triple-fuse to protect the drive-train from breakage. Of course, the tranny can still fall prey to missed shifts and/or lack of clutch hydraulic hygenincs.

As for me, I'll be keeping my ECU stock and keeping searching for a better technique to get faster times by without breakage.

Ranger

boosted_z06

Abuse mode is only for the automatic transmissions, not the manual.
PCM has more control with the auto since it has electronic controls the manual does not have so if PCM sees high wheel spin it not only pulls timing but also injector flow and torque converter.
LS2edit has the TM functions for our Z06 since the PCM still handles TM where the 2006 automatic uses a TCM so its the one limited to what can be tuned at this time

I had my tuner JR tune my Z06 with LS2edit and now the upshifts are way better. He said he tuned the TM but would not turn it off since it would cause long term damage to the drivetrain.

All model year C5s had TM and reason carputing was able to get LS2edit out quickly for the Z06 is its not much different then a 2004 Z06 as to the PCM code.

The problem that is lacking is no real tables we had for our C5 Z06s to adjust for knock issues.

Ranger

Hey Dan.

I drove my two C5Z to 500+ passes without breakage. I'm not worried about my tranny or motor. The rear axles do concern me. From the C6Z06 Rear End Issues thread (the sticky) we know that many folks have broken the CV joint. In now 27 burnouts, launches and strong-shift passes, I haven't broken one. Is that luck or the lower tire pressures I run? Dunno.

As for the clutch, I got 150-175 passes per LS6 clutch, and glazed them only twice in 500+ passes with at least a third of them being at 4000+ launch rpm. In marked contrast, the LS7 clutch glazes at a 4000 launch. So it remains to be seen how many passes it will give. I'll be surprised if it's 100.

Those are the only two weak spots that concern me relating to max straight-line acceleration.

Ranger

TetraU

Ranger,

It's just a thought. But could you have a tune and drive it for 2 dozen passes and then return the PCM back to the stock tune? It may help you figure out how to get around it.

jbp8653

Ranger, How should we launch the car to be sure we don't break right cv joint? My car is stock other than a tune. We edited out Torque Management. How will this change launch strategy to avoid cv breakage? Thanks, John

boosted_z06

If going by LS2edit there is a torque table for each gear as you see is stock table values is from 500 to only 3,000 RPM.
Each RPM range has a maximum torque allowed value. If using that to its RPM ( I added the HP in red values) you would have to stay just below the values to prevent PCM reacting my pulling timing

Ranger

Hi TetraU,

I could buy an extra ECU and have it programmed to either

(1) Change TM settings by say 50%
(2) eliminate TM

Then measure the effect on on the splits and incrementals...focusing particularly on 60', 330, 60'-330' and 330'-660'. That would probably tell an interesting story. And I suspect drop my ET into the 10s.

My estimate is that I'm paying a .2-.3 second penalty. That's not that much unless you want every last ounce, in which case, you need A-game driving to go with it. I say that because proper shift points make more difference than just .2-.3. Case in point, I short shifted:

• the 1-2 by 300 rpm (inadvertently I assure you) racing Wanted last Saturday, it cost about .1 sec.
• the 3-4 by 350 (again not intentionally) that day on an early pass, it cost 1.5 mph in trap speed.

The teaching point is that the car is VERY sensitive to proper shift points, if the goal is max acceleration. But measring the effect takes professional timing equipment and a drag spread sheet.

Ranger

Ranger

My advice is simple.

(1) Make sure the car is warmed up. Oil above 120.
(2) Keep the launch rpm below 3300.
(3) Avoid wheel hop.
(4) Learn to squeeze the throttle rather than hammering it to the floor.
(5) Don't burnout dry tires.
(6) Make sure your rear wheels are on the same surface before squeezing the throttle.
(7) If you run at the drag strip, make sure you air down the stock rear tires to 26-27 psi before you make each pass. Some cars WITH TM have broken the right axle shaft/CV joint at 30 psi at the drags.

Ranger

TetraU

Ranger,

You are the best driver on this board and one of the best posters. Thanks for sharing your hard earned insights. It makes it fun for me to check into this board here in the foreigne land. Hope to see you and Wanted race again soon, and this time please have someone make a video. Thanks ahead of the time.

Wendal

Cobra4B

Very interesting thread to read... love the methodical scientific approach you take.