I've been thinking about this cause i know my 3:73's aern;t the greatest for breaking mach 9. Or maybe it just my engine, tranny, gear setup. Cause i'm running a th-350 and when i have the ***** to WOT on the backroads i run out of RPM's in a hurry. Guessamation at about 120. But she'll sure get there in a hurry.

 

So what is the question. Figuring out gearing and tops speeds is independent of engine power. Engine rpm does come into play and lets you go farther per gear as the max rpm increases. Also technically you can be power limited if you have to weak of a motor. But it boils down to tire size, tranny gearing, and rear end ratio.

 

Whats your red line at?
My buddy has a TH350 and 4.10's
he revs to 6500 and thats 127
You probably are going into the 115-120 range

 

You can either upgrade to a built 700R4, so you have a 4th gear, or swap out your rears for 3.23s (big difference) or 3.42s (a mid step), or get smaller wheels. Any of those would raise top speed.

 

He would have to get bigger wheels and tire not smaller. The smaller ones have a shorter circumference meaning less distance per turn. The larger tires will move forward farther per turn dropping rpm. I would say gears in the 3.08 to 3.23 range would be needed otherwise. Or maybe a comination of both.

 

Whoops!

 

with 3.42's and a 700 mine will do 135 in third spinning 6300
and 165+ in 4th it just keeps pulling ls1 m6 cars can't run away on the highway since i put the 3-4 wot upshift valve in

 

Its time for an OD trans my boy....