Neo/Russ (66.83.53.142)
Rating: N/A
Votes: 0 | | Posted on Wednesday, March 26, 2003 - 12:16 pm: | |
Peter,
I've tried to use that Eaton calculator, but it's too limited in its choice of tire diameters. For example I use 3.15-80 R 22.5's. So I use the calculator Daris's site. It lets me plug in my true tire diameter and get exact speeds.
As to the speed to run a Series 60, Valley Detroit diesel says; "For maximum fuel economy, Detroit Diesel recommends gearing the vehicle so the engine is running 1450-1500 rpm at cruise speed or top road speed. This RPM range is also within the maximum rated torque range" This motor has way more than 200 ft.lbs. torque at the speeds I'll be running than the old 8V.
Last week I was at the Mid-America truck show and talked to engineers at the Detroit Diesel booth. "If you're running 80k in the mountains then gear it to turn about 1800+ on the flat, but if you're running LTL in Florida, slow it way down to get the mpg, it'll pull!" I'm going to be under 50k and don't plan to run the Grapevine every week, so I'm targeting 1450 rpm at 65/70. Here in Tennessee, at 75 everyone is passing you, so I need the speed.
Also, to turn those R's I need a .64 O.D. (Allison World B-500 = $$$$expensive) and my 4.03 (net 2.579) ratio. With all I've got to spend for the trans, I'm doing a lot of research from technical people who really know.
Just passing on what I've gathered so Larry and others have an idea that no matter what, they're facing a rearend swap or a tall O.D. |