Most of my reading online recently has been about the Detroit Diesel engine and the feeling I get from all of this is that one should lower their differential to 3.73 for the best fuel mileage with some scarifice as to top speed and initial movement...

any comments?

I would save the money for fuel, the 2 cycle DD's
are an engineering marvel designed for POWER from a bygone era of cheap fuel, again I doubt you would save enough to notice.

Although the 8.2L and 6.2/6.5L V8s were briefly called "Detroit Diesels", they are 4-stroke engines, whose designs are unrelated to the 2-stroke -53s, -71s, and -92s.

But mostly, to harvest beneficial comments, you should reveal what coach you have...

Now your avatar shows what you have!

MCC knew what it was doing, so its choice of differential is most likely optimum.

First I have no idea which engine you have.

Our Newell has an 8V92TA and has a rear end ratio of 3.33. This gives about 6.5mpg many thousand mile average at about 1700 RPM. This milage is about .5mpg less than the series 60 when equiped with the same tranmission (740 4 speed). Later units had 4000 series 6 speed and pumped milage to about 7.5. Newell built 2 units with 8V92 and 4000 series allison. RPMs dropped and MPG went up. I believe they also went to 3.73RE at that time.

The best HP per pound of fuel is 1600 to 1700 rpm for the 71&92 series. The 53 series is another animal.

quote:

Originally posted by Rusty:
MCC knew what it was doing, so its choice of differential is most likely optimum.

Here are a few specs for these coaches

Rear Axle Ratio 4.63-1
8.2l Detroit Diesel - 4 stroke V8 205 hp.
4 Speed Allison Automatic
9R x 22.5 Tires
Mileage ... 11 mpg approx
0-60 ... 36 seconds
40-60 ... 18 seconds
225" wheelbase
Approx Weight 19,000 lbs

MCR suggests 3.73 is better in several ways...