[XLR8STEVE]

First real track time on a new build.
70 GTO around 3850 race weight.
TKO600 2.87,1.89,1.28,1.0 gears
3.42 rear 12 bolt
28" tall tire
slow 60' and hard to slip clutch enough out of the hole. will stick the tires and bog. no real traction issues. starting to let clutch out about 3500-4000.
clutch is mcleod RXT twin disc.
engine dyno'd at 575H/597TQ
peaks at 5700H/4500TQ
time slip attached.
shifting at 5800 and going through traps in 3rd at 5950 ish.
seems my first 1/8 is slowing me down. want 11s.

Would a 4.10 rear help? Other advice on stick car launch?

[Stan Weiss]

Do you have a dyno sheet that you can post?

I would try leaving the line at a higher RPM

I would also try shifting around 6200-6400 RPM

Stan

[XLR8STEVE]

dyno attached.

[tom s]

With a stick shift I have found some lower gears help the 60fts.The car catches up to the tire easier.The converter in the auto cars can make the taller gear more useful.I would try a 3.73.Tom

[Scarebird]

What is your OD ratio?

[blueghoast]

I ran a 4:30 rear gear with a 2:78 first gear in my 4-speed at 3650 WT.
Car ran 11:61 at 116 mph with a little less HP. and was still pulling hard
through the traps. I would start there and this was my street car.
It wasn't a highway cruiser but did drive it to other towns for street racing.

GT.

[Lee]

Sounds to me that you need some carb tuning. What was perfect for the engine dyno can be WAY off with the engine in the car.

If you have a Holley, I'd start by playing around with your squirter sizes. Bogging off of the hit makes me think you need a bigger initial shot of gasoline. I've been able to change squirter sizes to tune the car for track conditions.

Some time on a chassis dyno may be beneficial to you as well. I would not be surprised to your power peaks occur at a lower RPM, on a chassis dyno.

Did you dyno with the same headers that are in the car? What sort of exhaust system do you have?

[XLR8STEVE]

Thanks guys, to answer questions below:
-i have a Fitech on it. controls timing also. 31 degrees all in by 3000. that is how it was dyno'd
-i read plugs a couple times after a run. slight brown mostly grey. i leaned it out from Fitech default settings, but with the plugs like they are, scared to go higher AF ratio.
-i totally agree with doing a chassis dyno session
-OD is .64 I am doing Drag Week this Sept with this car. 70 mph will be 2200 RPM in 5th with the 4.10, was 1840 with the 3.42

[Lee]

Add some enrichment fuel. FITech SHOULD have that option. I know where it is on FAST and Holley Sniper systems, but not on FITech. I bet you are lean at the bog (if you can do data logging) and just need some enrichment fuel. You will probably be able to tune that as a sort of "traction control", once you learn how to use it. With a manual and those tires, I bet you can eventually 60' close to 1.50.

If you get it on a chassis dyno, then play around with the timing curve. I bet it will run better coming in a little later. As you have a manual transmission, you'll be able to start your dyno pulls at a really low rpm. If you use a DynoJet, then take a USB drive with you and get a copy of your run files, for future reference. There are different ways of viewing the data, wheel speed or engine speed, different smoothing, etc. - sometimes you can 'see" something in one view that you don't in another.

[Scarebird]

Originally Posted by XLR8STEVE

Thanks guys, to answer questions below:

-OD is .64 I am doing Drag Week this Sept with this car. 70 mph will be 2200 RPM in 5th with the 4.10, was 1840 with the 3.42

My 600 has the 0.82 OD, should have got the 0.65 like you did - sounds like it will work fine with 3.73 to 4.10's

[KGTO]

I ran 4.33s, all timing was initial other than what I pulled out when the nitrous came on (only 150 shot) Jerico tranny shifted around 7. Launched around 6 on a 2 step. Make sure suspension is up to the task so it works better for you too