Roadrunner2

I revved up to about 3000 rpm and quickly released the clutch, which caused some clutch slip. Then at about 5700 rpm the engine would shut down, I shifted to 2nd and the engine went all the way to 7000 rpm with no problem. I tried this 3 times the same way and each time the engine would shut down at around 5700 rpm in first gear. After those tries, I went back to just a 2000 rpm launch, and first gear did just normal and the engine went to 7000 rpm. I did have both active handling and traction control turned off on all the above launches. I've never had the engine shut down in any previous corvette with the traction control and active handling turned off. Torque management is the only thought that comes to mind.

DDSLT5

outnumbered

I'm sure Ranger could entertain your question.

Roadrunner2

I forgot to say, I was on the newest, most coarse, stickiest pavement imaginable. The tires weren't spinning much at all, just some clutch slip.

dennis50nj

no tm retards timing shuts trottlebody

Joe0121

The sentance is screaming for a comma.

So Tm retards the timing and as a result shuts the throttle body?

Ranger

In first gear, when traction is very good and the tires are hooked, if you have the throttle on the floor, then your will hit the rev limiter way before the tac says you're at 7000.

On the C5Z we called that phenomenom "tac lag."

Some members are skeptical that the C6Z has tac lag. But mine does in those conditions; I've hit the limiter in 1st gear twice in 16 passes at an indicated 6000-6200 rpm. Once with a 3000 rpm launch in stock tires and the other a 3800 launch on DRs.

This 1st gear tac lag puts a premium on learning to internalize the rhythm of the LS7. That takes making passes and learning to feel with all the senses how close 7000 is while the rpms are eploding upward.

Ranger

outnumbered

So what you are saying is the TM lowers the rev limiter when it engages?I remember your day at MIR you had mentioned the lower rpm
limiter.

musclesbmf

SOunded to me like he was saying you indeed went to 7000RPM, it just didn't indicate on the tach because the Tach couldn't keep up under the conditions you had mentioned. That is why he was explaining the "tach lag."

At least that was my take on the explanation.

Ranger

Sorry I wasn't more clear, outnumbered. TM plays no role in this.

In the conditions Roadrunner2 (and I) described, the motor revs so fast in 1st gear that the tacometer reading lags behind the actual rpm of the motor. That means you hit the limiter (7100 actual) while the tacometer is showing around 6K plus or minus a few hundred.

The C5Z did the same thing in 1st gear in the conditions described.

Ranger

Joe0121

Is it the same tacometer?

outnumbered

Thank you sir.You are a gentleman and a scholar.Many of us appreciate
your participation on the forum.

Ranger

Don't know. But the electronics and engine management in the C6Z are substantially different from the C5Z.

The central point is that best acceleration is had shifting as close to the limiter as possible without kissing it. But because of tac lag, that is a challenge in 1st gear and takes practice.

Ranger

Ranger

Happy to lend a hand.

Ranger

bernrex

I've frequently experienced a tach lag of 200-300 RPM's. But, 1000 seems outrageous.

Is the digital HUD just as limited in its ability to chase the engine electronics ?

Ranger

Dunno, Doc.

I turn off the HUD at the drags and rarely look at the tac in first gear unless I hit the limiter. Then I look and log the approximate rpm that was showing.

Ranger

Roadrunner2

Thanks Ranger for your info. It sure thru me for a loop when it first happened, I even got stuck between 1st and second gear because I was so stunned and trying to figure out why the engine shut down early according to the tach.

greendot

That's the part I like!

robvuk

I've never experienced that much tach lag. My first thought is that the HUD does not have that kind of lag. It would be interesting to see someone verify whether or not this occurs on the HUD. It would then make sense to use the HUD instead of the tach in these conditions.