LT4Sam

All,
I'm planning a trip to the drags in a couple weeks and want to gather some data on what works for other people with these cars/transmissions. I have learned one thing during my short time with this car, and that is the clutch is an all or nothing thing when launching, feathering it or letting it out gradually will only result in spinning it rather than the tires.

So, what rpm to dump the clutch at to achieve the best 60' times without sitting at the staging line smoking the stock rubber?

Thanks,
Sam

Oh yeah, please try to factor in the existing mods (like the rear ratio)


[Modified by LT4Sam, 11:30 AM 9/13/2001]

No Ordinary 91

dumping the clutch really can't get you good 60', you are going to have to ride it a bit. I have been experimenting with my launch many times

If you dump the clutch to low the engine will bog, too high and you WILL roast the tires. If you aren't comfortable riding the clutch what i found work also is to hold the engine between 2500-3000 rpms and then hit the clutch the tires will spin a bit but then they grab pretty hard at that point hit the gas, but again too early and the tires start spinning and too late and the engine bogs.

My advise.......try some different launches and see what works best for you, if its your first time out don't expect real low numbers, getting these cars to hook is quite tricky. I am not sure if the LT4 have as much or more torqu than the L98's down real low, thats what makes the L98s tricky

MaxPower

With stock tires you will probably have to leave around idle and then dip into it. The 4.10's should give you good leverage and prevent alot of the bog normally associated with leaving at a low rpm.

Hutch

Pretty much concur with what Max said. Although I would bring your revs up to around 2000 or so and quickly feather the clutch out from there.

With stock tires, you most likely won't be able to get away with dumping the clutch. You'll just go up in smoke or bog down. Even with drag radials, with 4.10s I find I can't dump it any higher than 2400 RPM or so.

When I was running stock tires, it was a bit depressing when every LT1/L98 automatic got a hole shot on me, although I usually caught up right quickly. ;)

One thing is for sure, ain't no substitute for experience and that only comes with practice and loads of it. I know that I sure need more of it! :D

Mr Mojo

I launch my LT1 at idle with almost no tire spin and with half a tank of gas, I haven't experienced any bog at all.
Of course it helps if someone layed down some rubber before you.
I've seen street tired cars just tear up the starting line and that messes it up for everyone behind them, but they don't care because they made their run.

Polar LT4

With my LT4, my 60 ft. times are in the 2.1 to 2.2 sec. range. I only have the 3.45's & not the 4.10's. I get the same time if I launch off idle & let it bogg or if I launch at 2000 & let it spin. When I launch at 2000 I try not to let it spin but the spin is hard to control. BTW I'm running the run flat tires, which I know does not help me. I'll be getting rid of them later this month, but with the 275 Kuhmo's going on, I don't really expect my 60 ft. time to improve.

ericcer

I took mine out for the first time and was having no trouble getting 2.0 launches. I ride the clutch a bit and ended up at lanching at 3500 rpm and was still not getting any wheel spin. That was my last run before the rain ended it all. I was wanting to try 4k next. I was probably riding the clutch a little longer than you guys. Still getting used to the car. It is much easier to launch than my 98 T/A where I would rarely get a 2.0.

BTW, the car is 100% stock including the tires.