Engine load vs rpm? (Climbing: hold top gear at very high load, or downshift?)

[justme1969]

See lots of differing opinions too.
Looks like one for Myth busters or an rockett scientist.
But I go both directions here and say it depends upon the vehicle, speed, grade, and length.
Ive traveled that same section plenty in the past with two distinctly different cars; first 84 SVO mustang with turbo and 5 speed.
It would climb effortlessly most of the way with no change in the R foot @70but there was a banking LH turn that always sent Turbo boost higher thus more fuel required or I could travel slower and get same reaction before that point and have more loaded engine time, diddnt matter which really never noticed true economy difference.
Second car was 71 Coupe Deville with HIPO built 500 CI and turbo 400 trans. This vehicle could cruise up 1/2 way @65 mph with a feather on the go pedal.
But still chug to top @55 when it dropped a gear still virtually unloaded.
But let someone stick that Caddi behing thier R/v and put it at 45 mph and It would Roar sucking the hood down in second the whole way up.

Unloaded rpms do best IMHO most cases.
Use your pedal to tell ya how much fuel your using I guess.

[Baltothewolf]

Originally Posted by Xist

Seventy and sixty-five? How soon do you plan on investing in an MPGuino?

I meant going from 75 to 70. To answer your other question, I would buy it right now if I had even the slightest idea how to hook the darn thing up. I want one really badly to just give me that last edge but like I said, not the slightest clue where to hook it up to....

[max_frontal_area]

vehicles are usually most efficient @ peak torque. find out which rpm that represents and
drive close to it. while climbing i would prefer going a bit higher especially in a vehicle of older technology. of course you want to keep your engine from melting so higher rpms are favorable to keep your water pump moving. once you get that hill mastered try the "tejon pass" ;~>