Low HP car, M6, 4.33 gears, 27" tires launch help
 

I went to the track 2 weeks ago for the first time on my 9" with 4.33 gears, spool, chromoly 3.5" driveshaft, BMR rod ended LCAs and torque arm, UMI torque arm relocation, and 26x10.5 ET street bias plys. Stock replacement clutch, race weight 3245, full bolton M6 LT1 with probably only about 300rwhp. I tried a launch(semi-dump) from 4000 rpm and it had a good initial hit but then bogged and had to pull itself out, no tire spin, 20psi. Cut a 1.78 60' on my way to a 12.8 at 106.5 on the limiter at 6100rpm in 2400 DA not powershifting. I ran out of gear at the traps and was on the limiter in 4th so had to up to a 27" tire which is only going to cause me to get MORE traction at the line. Any advice on a launch or what I should be looking for? The torque arm is in the 2nd hole from the top on the torque arm relocation bracket. Ive read the threads, done a search, and have alot of experience at the track babying it with the 10 bolt, but nothing with a solid 9" that I have no fear of breaking. Should I just say FUCK IT and sidestep the clutch from 6000 and hope for a little tire spin? Or feather the clutch to try to keep it from bogging? Up the tire pressure, less tire pressure, lower the torque arm on the relocation bracket? No idea what to do, and the LTx shootout is in 1 week with no time to get to the track before hand.

HELP

if you ran out of gear with 26" and plan on more mods in the future 27" isnt gonna be THAT much more room to grow, id do 28's and dump it high

I calculated that the 27s will give me to about 111 mph, which is still low, but I needed a quick fix before the shootout. This winter I plan on a gear swap and going back to 26s.

6000 side step sounds like the best option here! back in my 5.0 mustang days i used to run 26 et streets with completely stock drive train and a 100hp nitrous shot. had it wired to come on when the clutch was let out. would leave on the 6250 factory rev limiter and it would dead hook pull the motor down to about 4500 and be gone. ran a best of 13.01 @ 108mph. everything was stock except for shifter and nitrous. you wont break that driveline with your combo
have fun
Beaudacious

What psi did you run in your et streets? Did you get any spinning or just a hard bog and a little clutch slippage?

ran 10-12 psi, left on the rev limiter every time NA or spray. on motor it would dead hook and bog(1.95 60') and on spray dead hook and lose about 2000rpm (1.68-1.72 60'). now keep in mind when running this kind of tire pressure the car is gonna wander around a bit on the big end.
Beaudacious

1.95 60' is worse than I do on street tires...theres got to be a sweet psi on ET streets that gives enough spin to keep the rpms up, I tried 20 psi and cut a 1.78, I want 1.65

Well, with my 26x10.5 et streets on 15x10 race stars and tire psi was at 22psi .I was getting a 1.65 60ft on Strano springs and kyb agx shocks. I do have a bit more power but this was also of a slight clutch slip with the two step at 5500. Definately look into a two step.

Raise the pressure - at some pressure it will spin. Then lower the pressure until you can launch at 6000 rpm without bogging below 4500. You need some wheel spin. You may need to go above 22 psi.

Thanks, Ill try 22psi and 6000.

Just an update on this, went to Cecil at -800 da, first pass, 1st and 2nd pass, 1st gear burnout, spun through the 60' to a 12.41 at 110 1.79 60'. 3rd pass, 2nd gear burnout, hooked so hard it scared the shit out of me and I lifted, 1.67 60', then forgot to power shift 2nd and missed 4th, still did 12,39 at 109. Rest of the day had wheel hop playing with launch rpm. Will post video later.

Some advice, don't lift :)

no lift on the shifts and i hope the clutch holds. if it was me a fast slip at high rpm would be the best to keep the rpm up and wheel speed (spinning or not)

Here is the video, I am in the right lane, you can clearly hear me lift a little on launch when it scared me, and miss 4th gear :(


I normally no lift shift, and did on my 2nd to 3rd and tried on 3rd to 4th but missed 4th. I was startled by the launch thats why I didnt do it for 1st to 2nd.