Gomer

I am taking my '15 Z07 to our 1/8th mile strip tonight for the first time. Just received and mounted my Forgeline 18' X 12.5' wheels w/ MT P345/35R18 tires. Tranny is M7, car is stock.

Yesterday I made some practice runs w/ and w/o LC. I am a little baffled as to what I can do to keep the rpm from dropping so low on the leave. Here is the info on both runs. I have PDR video of both.

OAT - 100 degrees
RH - 45%

Run 1
TP - 23.5 psi cold
LC on (Tr / Sport1)
Leave rpm - 4,000 rpm
RPM dropped to 1,200 rpm on leave


Run 2
TP - 23.5 psi cold
No nannies (TC off, Stabilitrac off)
Leave rpm - 4,400 rpm
RPM dropped to 1,400 rpm on leave

So I guess I am just trying to find the sweet spot using tire pressure and leave rpm. If some of you guys who have similar setups or experience trying to determine leave sweet spot on you cars have any advice or comments, I would appreciate it.

Thanks!

lawdogg149

Have you tried slipping the clutch out. Seems with DR's these cars hook pretty well. Try getting a little roll before coming all the way out of the clutch. I nailed a 3.0 sec 0-60 doing that. I liked 3200 rpms better on the street.

Gomer

Thanks, lawdogg. I have done that with other cars but frankly, I just wasn't expecting that the MT's would hook that hard. I'll give it a try tonight.

0Myhardtop

Forget LC homie

Lower tire psi between 18 and 22 COLD! Find which the car likes best...but start with the lower psi setting then go from there.

Launching between 3,500 and 4,000 seeems to have worked best for me. I do slip the stock clutches a little, never just plain dumping.

Try this (my apologies if already know this):
* DR's to 18 psi COLD
* Move seat forward/back upright - leaving room for your knees
* 1/2 tank of gas or less (less is best, but not too low)
* Pump up front stock tires to 50psi (optional)
* NO TC
* Drive around water box
* Back into water box
* Spin tire one good cycle
* Roll forward (roughly 2ft)
* Select 2nd gear (heat tires in second gear)
* Brake torque - Do burn-out (for a good 3 to 5 seconds)
* Now creep forward to Stage - in FIRST Gear - DO NOT dry hop!
* Once staged...
* Release clutch up to when it starts to grab...hold it there
* Bring up R's to around 4,500 rpms
* Launch car when last set of yellow lights go out
* Press gas pedal, while slightly slipping clutch...DON'T allow bogging
* Speed shift into 2nd gear (as fast as you can)
* Powershift into the rest of the necessary gear changes - no lift of throtle - just kick the clutch as you select the next gear as fas as you can
* Collect your time slip and evaluate
* Leave hood open while analyzing runs and between runs

That's it...this should get you going. Repeating runs will get you going faster and faster. Remember, you're there to learn the car and then go from there. Don't try going out to set the world on fire.

Hope this helps

Thanks,
Carlos

PRE-Z06

It being as hot I assume where/when you're running, first gear being as tall as it is with those larger than stock tires and the msrc transferring weight as well as it does, I think you will want to air(pun intended) on the higher side of what myhardtop said (all of which is good advice) as traction should be less of a problem unless prep is horrible. The stock clutch can take quite a bit of abuse, more than the c6z or zr1. The ideal 60' time will come from launching around peak torque. The lt4 having a table top torque curve should help you not have to introduce as much heat into the clutch caused by a higher rpm launch, though a taller tire requires more slippage to match engine and wheel speed without bogging. I recommend starting on the lower end of the spectrum with launch rpm and then increase slowly until you're just starting to spin, at that point you can try lowering psi to help it hook and then try increasing the rpm slightly again. Hopefully time permits you to make one change at a time to find the sweet spot.

Sincerely, Chris