You're still looking at it backwards, the vehicle is CONSUMING the same amount of torque, both engines have enough torque potential to achieve the unloaded "idle" speed of 2200rpm, but the percentage of each engines maximum torque potential at that throttle position is dramatically different. The cylinder & inlet pressures are going to be much higher in the smaller 110ci engine, & may be at 35-40% of it's max output on the level, when loaded on a grade those pressures increase and the output efficiency goes up until it has reached maximum and the vehicle will settle at whatever mph that is. The larger engine, not to mention supercharged, may only be operating at 8% of it's max potential output, thus it has much more capacity for increased load before reaching maximum efficiency and output.
