So I finally got my Doug Nash overdrive installed along with the new speedo gear etc. The vehicle is a 1988 E250 with a c6 and 3.54 gears.
My first impression is that I really like it and that it makes it much easier (almost too easy) to cruise at higher speeds on the hwy. I put a total of 318 miles on it with about 80% of it being hwy. Mileage was 14.9mpg. This is on the upper end of the mileage I would get for the same route prior to the install (I would range between 14-15mpg). However, instead of having the cruise set at 60-63mph I set the cruise at 73mph. Wind resistance has a big effect on mileage of my van since it has the aero of a barn. With that in mind I think slowing down to about 65mph should show some pretty good gains.....maybe a couple of mpg.
Flatter terrain would help too. I took a road trip into Ohio a few weeks ago (to pick up the DNE2) and was able to get a little over 16mpg with the cruise set at 65mph. Thinking the overdrive I would have been able to hit about 18mpg.....if I can get in that range I will be happy.
All the temp gauges seemed to run a little lower.....EGT, Trans and Coolant.
Acceleration, while noticeably slower, isn't too bad and the O/D can always be turned off with the push of a button. I am also thinking it will help if I am towing anything a little heavier since I will have a 2.5 gear available.
The real test with be in 2 weeks when we head out on a 2000 mile trip.
__________________
My first impression is that I really like it and that it makes it much easier (almost too easy) to cruise at higher speeds on the hwy. I put a total of 318 miles on it with about 80% of it being hwy. Mileage was 14.9mpg. This is on the upper end of the mileage I would get for the same route prior to the install (I would range between 14-15mpg). However, instead of having the cruise set at 60-63mph I set the cruise at 73mph. Wind resistance has a big effect on mileage of my van since it has the aero of a barn. With that in mind I think slowing down to about 65mph should show some pretty good gains.....maybe a couple of mpg.
Flatter terrain would help too. I took a road trip into Ohio a few weeks ago (to pick up the DNE2) and was able to get a little over 16mpg with the cruise set at 65mph. Thinking the overdrive I would have been able to hit about 18mpg.....if I can get in that range I will be happy.
All the temp gauges seemed to run a little lower.....EGT, Trans and Coolant.
Acceleration, while noticeably slower, isn't too bad and the O/D can always be turned off with the push of a button. I am also thinking it will help if I am towing anything a little heavier since I will have a 2.5 gear available.
The real test with be in 2 weeks when we head out on a 2000 mile trip.
__________________
