I'm looking at upgrading the gears in my 1996 F150 2WD truck and would like to know what the ideal cruise RPM should be for this engine for the best balance between power and MPG.

Right now the truck has 2.73 gears in it and 5th gear is basically useless below 75MPH, especially when going up a moderate grade on the freeway.

I've been told by a local shop to select gearing for a cruise RPM of when peak torque occurs, which they calm is the point maxium efficiency. According to the original sales the engine is rated at 265ft-lbs of torque @ 2000 RPM and would this also be the ideal RPM I should cruise at?



Any advice would be greatly appreciated and thanks in advance.
Mark from San Diego

 

I believe it's at 2200 rpms.

 

Technically, choose a cruising range, and select a gear that puts you in the middle of that range for peak torque. If you typically cruise in the 50-75 mph range, select a gear that puts 2,000 (or 2,200, depending on year) at about 62 mph (60-65). This allows you to be on point within a window of cruising speeds you are likely to use. However, keep in mind that this might not be the best way to gear for heavy hauling, if you do that alot, because good gearing for unloaded use can kill your mileage under load, when an agressive gear might give you better economy. If you are loaded less than 50% of the time, the suggested method will perform best.

 

When my truck was using a tranny AOD it gaves me about 18-20 MPG cruissing at 70 MPH@1850.

Now I had an E4OD and it gives me just 16 - 18MPG, same configuration and cruissing at 70 MPH@2100

Both driving unloaded in a flat highway