HMMWV HUMVEE High Output Engine Upgrade An improved and redesigned HMMWV HUMVEE engine based on the OEM HMMWV HUMVEE 6.5L that will drop-in and bolt-up to any HMMWV HUMVEE with no modification to the vehicle. Custom horsepower and torque range tailored to any unique application, terrain and operating environment. Up to 79 increase in horsepower and up to 60 increase in torque over the standard OEM HMMWV HUMVEE.