I had a question about launching techniques. I have a '92 RS Camaro with a TBI 305, 700R4, and 2.73:1 gears. If I stall it up and launch it spins, but it gets out of the hole pretty good. If I don't stall up and just hammer it, it spins a little and then bogs. Is there anything I can do besides gears that can help? I'm in the process of building the car up, but I would like to retain the stock gears until the rearend gives up(if it ain't broke, don't fix it!). Plus, I like to play on the highway and the gears are fun for that. If you have any suggestions, let me know.

 

No help - But I have the same set up, and knwo what ya mean - low RPM's and high speed I find that I dont need to hammer it off the line - just pop the gas, then when 'its time' put it to the floor. Thats the best I can explain it - I play with it all the time, mostly just lauches b/c I dun wanna get my *** pulled over... You'd be suprised how much torque the L03 puts out, 255 ft lbs...wow...

 

do you burnout before you race? because if your tires aren't warm there is less tire grab. and how high is your rpm at take off to you just let it idle the stomb on it or to you give it some gas and hold the brake? i normal tach mine just enough so the the engines doing about 1000 to 1500 rpm but not spining the tires thats how i take off and the results are pretty good. with my 305 carbed enige i got 16.4 not to bad for a all stock engine. but i put her away this winter and have been doing some major work on her i have headers and a 270h comp cam and flows allready plus some crome.

 

Do not burn radial street tires. They just get gooey and slippery. If it's 60* outside then the tires are plenty warm. Let a little air out, not a lot, because raials lose their contact patch if you let too much out. I'd say 15 lbs. is as low as you want to go. Since this is a 2.73 I'm guessing you have a peg legger? Let more out of the right side than the left. Spin the tires a little bit just to clean the rocks and stuff off of them. I'm talking about a couple of rotations. Bring the engine up to 1500 against the converter and then walk it out at about 3/4 throttle. After about 10 or 15 ft. just enough to get it rolling, then drop it all the way. That's how I got my 2.73 lg4 peg legger down into the 15's.

 

Are you nuts? 15 Lbs on a street tire is way to low. I pull 1.98 60' on 25 Lbs on drag radials. Dont let any air out of street tires. If you do no more than 2-5 Lbs just to make you feel better.

Just becuase of the 2.73 doesnt mean peg leg. RPO G80 and GU2 = 2.73 posi. I know I have one. The RS is a better idication of the peg leg.

I stall my posi 2.73 to 1750 and let it fly but I'm on BFG drag radials, I hook well.

 

You can increase the contact patch of a radial tire by letting out pressure until the patch begins to deform because of the radial design. We both agree on this. I'm not saying the LG4 was pulling anything under 2.0 60 ft., but it would definately spin the tires. Changing tire pressure helped eliminate that, by evenly distributing torque to both wheels. Not to rain on your parade or anything, but 1.98 60 ft. isn't exactly setting the world on fire. Maybe if you said 1.60 or 1.70 I'd be impressed. The MAX tire inflation pressure on my street tires is 35#. Most drag radials are designed for low pressure. Maybe you just have the ...inexpensive ones. I could launch evenly with 15# in the right side and 25# in the left side.

 

Your right 1.9's doesnt get the tires off the ground but, a 1.98 out of a LB9 with 2.73's is damn good. Anyone else agree? As for cheap drag radials, BFG 255/50/16 dont think so. As for tire pressure I'll let you in on a little secret. After my cam change last year, I went to the track. I started out running my tires at 18 psi, I had lower 60' times on street tires and before mods. What was happening was my car didnt have the TQ to get the car rolling with 2 flat tires in the back. After the run I went back to the pits very upset that all my mods and I got slower. The guy in the pits next to me, a vet drag racer came over to give me a hand. We checked timing and fuel presure. Next he checked my air in my tires. I had to low in the front and to low in the rear. We took the fronts up to 35psi and the rears to 28psi. I went and made another run big improvement. Next step was to let the air out of the rear tires 2psi at till my times stoped getting better. 25 psi is the magic number. Thats what I suggest you try to get yor best launch.

 

That's it. Street tires are not designed to be let down. The radial tires actually resist flatening out. When you let to much air out then they cup in the center.

 

Blah blah blah
My data says this your data says that so who is write?

Basic facts
1. radials tire patch increase with a with air let out to a certain point.
2. What is that point? Well that depends on your tire. You are just going to have to test it in a nice clean parking lot or driveway or something like that. You want a nice even shade of black all the way across. If it lightens up in the middle then not enough pressure put more back in.
3. You are just going to have to test and see at the track show up early on a wednesday night and be ready with a bottle or air and a really accurate tire pressure gauge.

 

I went from 2.73 pegleg to 3.42 posi, and added Spohn LCA relocation brackets, and homemade sfc's.
I have 255/50R16 Toyo Tires out back on 4th gen T/A wheels, and I hook up very well.

If you aren't changing the entire rear end, go with spohn LCA relocation brackets, LCA's, and a 3.42 or 3.73 Posi unit, and you will be a lot better off. Get some new tires or wheels and tires.