PAAG Engines 1.36

For vanilla trucks, Kenworth W990 by Harven, Freightliner FLB by Harven

There's no need to go much beyond 1360/1430 rpm. You won't get more power with high rpm, since horse power does not count in the game, only torque. Kickdown goes to ~1600.
Set automatic shift on adaptive!

PAAG 500 HP:
torque: 2508 @900-1430 rpm
secondary_torque: 2250 @900-1430 rpm
secondary_torque_gear_ratio: 1.5
volume: 12.9
engine brake 1 Step @1.8

rpm_range_low_gear: (750, 1380)
rpm_range_high_gear: (850, 1110)
rpm_range_power_boost: (150, 400)
rpm_range_engine_brake: (1350, 1800)

torque_curve[]: (500, 0.5)
torque_curve[]: (750, 0.8)
torque_curve[]: (900, 1)
torque_curve[]: (1400, 1)
torque_curve[]: (1600, 0.8)
torque_curve[]: (1750, 0.4)
torque_curve[]: (1900, 0)

PAAG 650 HP:
torque: 3000 @1000-1360 rpm
secondary_torque: 2700 @1000-1360 rpm
secondary_torque_gear_ratio: 1.5
volume: 15.7
engine brake 1 Step @1.8

rpm_range_low_gear: (850, 1470)
rpm_range_high_gear: (920, 1200)
rpm_range_power_boost: (80, 300)
rpm_range_engine_brake: (1350, 1800)

torque_curve[]: (500, 0.40)
torque_curve[]: (750, 0.7)
torque_curve[]: (900, 0.9)
torque_curve[]: (1000, 1)
torque_curve[]: (1360, 1)
torque_curve[]: (1400, 0.87)
torque_curve[]: (1600, 0.7)
torque_curve[]: (1750, 0.4)
torque_curve[]: (1900, 0)

This are low rpm "Boat" engines so one can drive at super low rpm. These makes the truck feel more like a tractor with a low-rpm long stroking engine. They don't stall like SCS stock engines.

Engine sound is subject of change