VT Diff Ratio's

[crew chief]

You are gonna make it use more fuel as it would be under load more often, the trans is where you could make real gains, swap to a t56 or t6060. The six speed offers 2 overdrives getting those rpm's way down at cruising speeds shouldnt cost much more than 3 or 4 grand which you would save in fuel costs in under a decade

 

[vaxx]

This might be an old post, but what he originally asked for is a good idea if you have a decent engine. Reduce the final drive, make fourth the same total ratio the same as fifth, end result is like driving a six speed without using first

I speak from experience having owned an XB Coupe with a overbored worked 460 in it and runnina toploader with a 2.72 ratio nine inch. Wish I still had it, but I always wanted to try 2.6 gears in it, had the torque and long legs, I would be changing into second and the guy next to you would be grabbing third going backwards and would break taction at 120 in third with ease.

I would be interested in seeing if he managed it and his impression

 

[losh1971]

From my understanding the 5L with 4 speed gets optimal economy from the 3.07, or 3.08 depending on the the diff. Where as V6 sweet spot is 3.45s or 3.46 again depending what you have.

 

[vr304]

I highly doubt going to a 2.7 or 2.8 ratio diff in a vt 5 litre would make it better on fuel and that’s even if they made those gears to suit that diff? usually going to a 3.45 ratio improves things all around with fuel economy, acceleration etc