My car is going to have about 500-550 horse power, and hopefully similar torque. I am getting a 12 bolt soon and wondering if anyone had any suggesstions on to what type of gear and posi to get. I don't know what holds what and don't want it to break. Your suggestions would be greatly appreciated.

 

Gearing depends on how you intend to use the car. On the dragstrip you want the engine to be at redline at the finish line. Gearing will depend on engine shift rpms and tire size.

On the street you'll want around mid 3.xx gears with a 3 speed auto and 3.73's with an OD. Again it will all depend on tire size and tranny selection. Deeper gears such as 4.10 can be used if the rear tires are very tall 28"+

500+ HP is nice but not for a street car. You'll have lots of problems trying to get that power to the ground.

------------------
Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.447 altitude corrected to 10.99
Best MPH on a time slip: 119.42 altitude corrected to 124.86
Altitude corrected rear wheel HP: 493
Best 60 foot: 1.586

Racing at 3500 feet elevation with a typical race day over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

So would a 3.90 gear be what you are saying would be ideal. I am going to drive it on the street but it is not my everyday car. I will use it as a fair weather driver. Thank you