The 4.6L engines utilize a different type of power booster than the conventional vacuum-type. The power booster is called a Hydro-Boost booster and is manufactured by Bendix. The Hydro-Boost booster is powered by power steering fluid. Vehicles equipped with 4.6L engines utilize a Hydro-Boost booster because the engine does not produce sufficient vacuum to activate a vacuum booster. The Hydro-Boost booster uses pressurized power steering fluid, provided by the power steering pump, to multiply the effectiveness of brake pedal movement. In the event of disrupted flow of power steering fluid from the pump, the booster has a reserve system (accumulator) which can store enough pressurized power steering fluid to provide at least two power-assisted brake applications. After the reserve fluid pressure has been used, the brake system functions as a conventional manual system. The Hydro-Boost booster is mounted in the same place (between the master cylinder and engine firewall) as the conventional vacuum power booster.