Posted by Fred Coldwell on Friday, March 26, 2004 at 3:27PM :
In Reply to: Re: Fred - posted by AAA on Friday, March 26, 2004 at 12:06PM :
AAA - I figure a 900-16 tire on an axle with 4.88 gears turns about 2,830 rpms at 60 mph in 4th gear (1:1) of a 4 speed transmission. That's awfully high revs for a diesel. With a 0.80% overdrive 5th gear tranny, the rpms would drop to about 2265 at 60 mph, more reasonable but I'd guess above the peak torque of the diesel engine. What is the top maintainable rpm's on an older Cummins diesel? What is the corresponding top speed of a W300 with 4.88 axle gears after spending $3,000 to $6,000 or more to shoehorn in a Cummins diesel and 5 speed OD tranny? Seems to me installing a diesel engine in a 4.88 axled W300 would result in a truck with a very low top end speed. Such a truck would not be practical for long distance Interstate highway crusing, where the better mileage of a diesel would presumably be most beneficial.
I think one would be cruising at the top end of the diesel's rpm range on Interstates in a 4.88 geared W300, even one with 11.00-16 tires. What do your numbers show?
Follow Ups: