a engin will make peak torque @ say 4000 wide open put with less throttel opening mabe 10% throttel the torque curve moves down to say 1800 because theres not enoufgh air fuel to push it much higher. fo example drive in 1st gear at 2000 ad watch your peadel then 4000. it will take at least dubel the throttel to cruise @ 4000 because the rotating mass of the engine is limiting the rpms when you dont give it much fuel. wide open is another story