I have been messing around with gear sets I have tonight and can't find one that will work to pull right......quick scenario roadster pu, with sbc solid lifter, 39 trans and a quickchange, my goal is to launch it from a start in second gear and just have to shift it once, I got as high as a 4:11 and it still doesn't seem like enough to pull it out of the hole hard enough, so basically how low can I go without over reving in the 1/8 maybe a 4:86 or even more?
I had a set of 5:13 in a Camaro years ago with a 4 speed. I could take off in 3rd with no problem and take it down to 10 mph in 4th and still get going
You need to give us what your max RPM and current tire diameter before we can give you the help you need.....................just as a guess I would say you need around 4.56's/4.88's, but without how many R's you want to spin and what you tire size is............it's a guess. OR; http://www.cprparts.com/HPcalculator.html
Is the second gear start to try and not hurt the ******? Also, what kind of quickie do you have? What kind of traction? Are you looking to go as fast as possibe, or go as fast as possible with out messing up hard to find parts? The best case would be ditch the 39 box for something that you could start in low gear with and get some slicks or at least some drag radials. A stout street SB Chevvie would do just fine with a set of 4.11s or 4.56s. You could slip in a set of 6.50s, but it is nice to be able to drive home with out changing the gears. For comparison, my daily driver runs the 1/8 in 7.30@ 96mph with 3.89 gears (29 in tire) and I am just shifting into third at the lights. Good luck, -Abone.
I would try 4.86 to 5.13. I run a quick change in my altered with a Pontiac and put a 4.25 ratio in it for the 1/8 and it was a big difference from the 3.75 I run in the 1/4. my Pontiac only turns 5500 to 5600 r.p.m's and you small block most likely turns all of 6000 r.p.m's if not more. I take it that first gear is a short gear? Jon
Tire size is a 8:20x15 so they are about 30" tall, it's halibrand quickchange and yes launching in second may help save blowing it in a million pieces again, motor revs fine to about 6500.
Anything from a 3.56 gear to a 4.56 gear isn't going to make much difference... your MPH might change, but the times will be about the same. To get a good 60 foot and change your ET, you need the right amount of torque and traction... Sam
I'm not looking to be the fastest and traction doesn't matter since they are just bias street tires, just best ratio so i can launch it in second and still go 85ish mph by the 1/8 mark.
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