F350 Super Duty vs 3500 Denali vs The Ike Pulling 30k lbs

Cummins12V98 wrote:
Thanks for the reply!

Just looked at a video I did right after getting current 15 DRW and 16 DRV heading South I-5 coming up the last 4 miles to Ashland pass. The RV and truck were I would guess 32,500# or so. The whole time I was in 4th at 49-51mph. In that situation I bet a gear in-between 3 n 4 may have made a couple mile per our difference. Not sure what RPM I was going but it sounded like it was not very high.

It was probably running about 2150 rpm in 4th. Even if downshifting at 50 mph into third with the Aisin would have put you at an rpm where the Cummins makes more power it wouldn't provide any gain in speed because the engine would be revving some where around 2900 rpm which is already beyond the rpm of its peak power level. The other thing with the Cummins is that at 2800 rpm it makes 400 HP and at 1800 rpm it makes 343 HP, so it's likely making about 367 HP at 2150 rpm. If it had a gear half way between 3rd and 4th, the engine would run at 2475 rpm in that new gear. 2475 rpm might gain you about 16 additional HP. 16 more ponies isn't really going to buy you a whole lot of speed anyway ... probably would be about 2 mph.

Edit : Oops I was thinking about the 2019 Cummins. Your 2015 would gain quite a bit with an in between gear .... probably 6 or 7 mph.