I have seriously considered re gearing my rear axle to raise the mph the peak torque of my m11 occurs.
I understand the wind resistance issue but I bet I can get 9 mpg+ at 70 on flat ground that way.
The interstates are not a problem at 60mph but the secondary roads have the truckers on my tail fairly often
Bob
Regeared 3176 marquis in 1991 to 3.21's if memory serves me. Had only a four speed trans.
Probably 3.42 or similar numbers. Not sure if the regearing pencils versus buy more fuel.
As the marquis were brand new then the gear sets were swappable from the gear guy.
Our 95 U320 with the M11, Allison 6-speed and stock gearing (3.91:1, I believe) seems to be optimum. I can find absolutely no reason to change it.
Unless you want 1350 rpm at 65-70 not 60.
I find if I can go 60 normally I can go slightly faster.
Monaco did it in the early 90's with a two speed rear axle. No six speeds yet.
Allison held back the trans four years as they told me in 89 that the had just rebuilt the production line in Indianapolis as would not release the world class trans they were displaying until the line tooling wore out.
No competition was the reason I was told.
I strongly asked for an earlier introduction in 1989 when I had the Allison guy on the phone.
Not sure how much difference in the mpg is at 1500 rpm versus 1350? Ten percent more rpm equal ten percent less mpg?
Even 65 or 68 mph for my uses might be better.
More hp normally gave better not worse mpg. Fun to turn up the m11 at the same time.
Shop mechanic mentioned Pittsburgh power for modded boxes.
We regeared and reprogrammed the marquis 3176 and got better performance and increased mpg.
Bob
Hmmm. 10,000 miles a year fuel is 25% of annual expense..... Save 10% on fuel, save 2.5% of annual expense.
I just hit the pedal and fill up when below half.....
Maybe I am lazy....