Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - 383 build kits?
Thread: 383 build kits?
View Single Post
  #13 (permalink)  
Old 11-13-2012, 12:11 PM
techinspector1's Avatar
techinspector1 techinspector1 is offline
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Zephyrhills, Florida, USA
Age: 75
Posts: 15,341
Wiki Edits: 326

Thanks: 1,504
Thanked 2,024 Times in 1,564 Posts
The problem in choosing a transmission and a rear gear is getting both ends of the equation to where they will be effective for every day use.

I might use a first gear final drive of 10:1 (also called starting line ratio) and a top gear final drive of 2.90 or numerically lower with a ~28" tire. Multiply the rear gear ratio times the first gear ratio to find the first gear number. For instance, a 3.55 rear gear times a 2.87 first gear would yield a 10.18:1 first gear final drive ratio, assuming a ~28" tire. A taller tire might require a numerically lower rear gear. A shorter tire might require a numerically higher rear gear. The same 3.55 rear gear with a 5th gear of
0.82:1 will yield a top gear final drive ratio of 2.91:1, making all gears useable in everyday driving or for drag strip use. You don't want the cruise ratio too low, numerically, if you plan to use any kind of decent cam timing. For instance, if the cam begins making power at 1600, then you might want to cruise at ~2500 to be "up on the cam" at highway cruise speed. A 2.91 final drive ratio with a ~28" tire will cruise at 72 mph at 2500. The Tremec TCET4618 5-speed fits the bill here, with a torque capacity of 600 ft/lbs and the right gear ratios.
TTC: TREMEC Transmissions
I know what you're thinking and the answer is no. You will never get out of 4th gear on a 1/4 mile drag strip unless you're building a 1,000 hp motor and mounting it in a 2,000 lb car. The average "hot" street driver will post a trap speed of ~115-120 mph in the quarter. With the above combination, you'd be at 120 mph at 4,200 rpm's in 4th gear, so like I said, you'd never get to 5th gear in the quarter mile.

Last edited by techinspector1; 11-13-2012 at 12:30 PM.
Reply With Quote
The Following User Says Thank You to techinspector1 For This Useful Post:
Camaro R/S LT (11-13-2012)