The 7.3L Ford Powerstroke engine is the largest diesel engine ever installed in a pickup truck straight out of the factory. The 7.3 Powerstroke is sometimes confused with the 7.3L IDI. That engine was used in Ford pickups between 1988 and 1994. The biggest difference between the two is that the 7.3L Powerstroke has direct injection. Inside the engine of the 7.3 Powerstroke, you will find a conventional oil pump but you will also find a second oil pump, the High-Pressure Oil Pump (or HPOP). It pressurizes the oil up to 3000PSI and is fed through an oil rail to all eight injectors.