According to Wikipedia...
RobVG — (archived)
B52 Pratt & Whitney TF33s (total thrust 8 × 17,000 lb) = 136,000 lb
Here
A 66,500 lbf (296 kN) thrust version (GEnx-2B67) will be used on the 747-8
Here
Not sure what the difference might be between "lb" and "lbf".