Ford 6.7L 1050 ft lbs TQ at 1,600 rpm, 475 HP at 2,800 rpm

blofgren wrote:

Grit dog wrote:
^True statement, but pursuant to ksss post, the Cummins has a smaller rpm range and more cogs would help the option and ability to pick the operating characteristics.
My G56 is a glorified 5 speed with granny gear and I can run 85-90 mph all day but she's screaming. And loaded heavy, I sometimes have to settle on a particular speed that I can pull and keep egts in check vs picking the speed I want and having a gear to accommodate it.
The low rpm range of the C will benefit greatly from more cogs. Moreso than the higher revving V8s in this respect, IMO. More IS better in this case. For everyone.

Agreed. I too have had issues when loaded heavy on steep grades with no ability to get a run at it where I’m caught between 3rd and 4th gear on the G56; lots of power in 3rd but can’t quite hold 4th. Oh well, the old girl is reliable and paid for! :B

That is because of the gear ratios of the G56. Due to having a granny gear, you essentially have a 5 speed with one overdrive and the rest of the gears are spaced out too far apart to accommodate. The 68RFE/Aisin has less of a spread and has two overdrive gears.

G56 spread
1st/2nd:-45%
2nd/3rd:-40%
3rd/4th:-34%
4th/5th:-24%
5th/6th:-26%

68RFE spread
1st/2nd:-43%
2nd/3rd:-23%
3rd/4th:-29%
4th/5th:-18%
5th/6th:-23%

Aisin spread
1st/2nd:-46%
2nd/3rd:-32%
3rd/4th:-25%
4th/5th:-23%
5th/6th:-18%