V engines. The piston with a hole is from a cummins. Similar to that of a semi truck. The big engines are 3,000hp and up. The big motors waiting for fuel are 4,400hp. All of which drive generators that power electric motors.
Here's a link to the cummins engine. Each genset has three of those.
The big motors are single engine.
Here's a promo from GE about the new engines
http://www.youtube.com/watch?v=Q_U3ZsVP1VY