Vulcaneer wrote:
NC Hauler wrote:
..With the 10-12, cruising at 60, rpm was "right at" 2 grand....the Aisin has me about 200-250 rpm lower, (around 1750-1800), mpg is up (thanks to the DEF? lower rpm?, :)
Jim, I find that interesting. I wonder what your rear axle ratio is. Just curious is all. I'm sure you mentioned it....I just forgot.
One of the things I find interesting about my Ford is that with the 20" wheels and 3.55 RAR, the engine speed at 65 MPH is right at 1600 RPM. Guess what RPM the MAX torque (850 Ft Lbs) is spec'd at? That's right. It's spec'd at 1600 RPM. And I believe it is pretty close to that.
Because when towing my 14,000 pound trailer at 65 MPH, it can hold 6th gear for most of those mild up hills and overpass humps. Does not down shift all that much. Maybe I am giving engineers too much credit. But I think they had this in mind when spec'ing the whole drive train.
However running at 55 MPH at about 1400 RPM, it will downshift on small grades much sooner. But overall MPG stays pretty much the same as at 65 MPH.
I believe this is one of the reasons, for getting between 11.5 to 12 MPG towing at highway speeds.
I raise this as simply a point of interest. And to bring up maybe some real world differences between the two brands. Not to say one is better than the other. Just different, is all.
This 13' came with 4:10 rear end...I've seen a comparison of the Aisin tranny and it's 6 differnt gear ratio's versus the 68 auto I had in the 10 and 12, (both of those also had 4:10 rear end), either on this forum or the Cummins forum and found it interesting, but again, not sure which forum. Haven't towed yet and probably won't for a month or so while figuring out which route to go with adapter to mount hitch, but empty, in cruise at 60-61 mph, truck taching at 1750 or so, I looked at it again this morning when driving to work to make sure I was right.
Don't know the difference between other manufacturers rpm when crusing or towing....Can't remember about the 07.5 Chevy Duramax Dually I had till 10'....it had 3:73..as do all D/A, unless they've changed it now.
