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Topic: Economy mode (Read 1073 times) previous topic - next topic

Re: Economy mode

Reply #25
If you want an excellent insight into RPM for best MPG, LISTEN TO THE 18 WHEELERS.  All (certainly all the privately owned ones who pay for their own fuel) climb those grades (yes, with more than twice our weights) JUST ABOVE PEAK TORQUE RPM.  THAT IS THE BEST MPG.

Now, if coolant temperature is rising, MPG takes a distant back seat to temperature.  Higher RPM, slightly less than WOT is much better for cooling.  It is also better for those who are frustrated by looking a few MPH on those grades.
As a former trucker. You are correct. Torque gets work done, HP maintains the work. The hard thing for all the indy 500 drivers in buses is that to climb a hill at max efficiency, You need to be at max torque. Which means slowing/shifting down so torque multiplication (lower gear) lets the bus maintain speed at less than full throttle.

When I owned my Kenworth W900 with a 15 liter Cat engine rated at 500HP-1950LbFt torque, 13 speed tranny. Pulling two FedEx trailers 60,000lbs across Northern Wyoming at 75MPH. I would get 5-5.5 MPG by shifting to stay at max torque.
Jerry & Nona and Kimeru the cat that thinks she's a dog
1998 36' WTFE U320  #5314 Motorcade #17711
USAF 1975-1995
2019 Subaru Crosstrek 'toad'
2003 Subaru Legacy touring car
jerry Fincher | Flickr

Re: Economy mode

Reply #26
Your good then,  mode on for the rolling hills.
 We just retuned from the Texas hill country and I went through the 5th to 6th thing.  Wish this thread would have started before, I think I already new about the mode thing but spaced it.

Yep,
sure missed that memo..............learn something new about these machines just about every time I log on to this forum, a truly great resource.  ^.^d

Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Economy mode

Reply #27
As a former trucker. You are correct. Torque gets work done, HP maintains the work. The hard thing for all the indy 500 drivers in buses is that to climb a hill at max efficiency, You need to be at max torque. Which means slowing/shifting down so torque multiplication (lower gear) lets the bus maintain speed at less than full throttle.

When I owned my Kenworth W900 with a 15 liter Cat engine rated at 500HP-1950LbFt torque, 13 speed tranny. Pulling two FedEx trailers 60,000lbs across Northern Wyoming at 75MPH. I would get 5-5.5 MPG by shifting to stay at max torque.
Torque is what gets us up the hill. Horse Power is what determines how fast we get up the hill.
Tim Dianics
Pam Sapienza
Vader PupZilla Labrador Canine Beast (AKA Pup)
Columbia, MO
1996 U320 4000
2021 Jeep Gladiator, Diesel