The biggest I messed with was Rolls-Royce RB-211 (42,000 Hp) for the Northern Border Gas Pipeline. At the time, Continental was using the same engine base for 757s.
The “big boys” (heavies) were easier to work on...the “little guys” (fighters) weren’t too bad, but in the jet, they were a royal PITA...
There are days I miss it, and days I don’t...but would go back to working on engines if the conditions were right.
Don’t know if it’s still that way, but when I lived in Alabama in the 1970’s, the Alabama Gas Company’s HQ building in Birmingham got its electricity from a GE J-79 jet engine turning a generator. It was set up in the basement and ran on natural gas. I always wondered if you could hear it howl like a F-4 Phantom.
The 79 was also used in the B-58 Hustler and the F-104 Starfighter. Great engine.