997 Turbo: The Last Mezger
Updated: May 6, 2021
So we had the engine out of a lovely 997 Turbo, and decided we’d be remiss if we didn’t point out a few things. The 997.1 Turbo was the last of its kind. The 473-horsepower 3.8 liter flax-six is based on the 911 GT1, and is the last turbocharged Mezger engine. That alone makes it special, but the details make it extra unique.
1. CHILLED FUEL
The 997 Turbo uses the car’s climate control system to provide cooling to the fuel lines so that the twin-turbochargers can perform at the optimum level more of the time.
2. EQUAL DIAMETER INTAKE TUBE
This intake tube is packaged tightly, both around the engine and within the engine bay, but it still maintains an equal diameter throughout, despite the way it squishes and contorts to fit the space.
3. POWER STEERING-ASSISTED CLUTCH
The clutch is assisted by power steering pump to make it easier to engage. The driver enjoys the benefit of a heavy-duty clutch without as much of a leg workout.
4. TRUE DRY SUMP OIL TANK
Many modern Porsche models in this era switched to wet-sump lubrication, but the 911 Turbo uses a true dry-sump setup, allowing for more reliable oil flow, no matter the cornering loads. Helpful for a car that was tested at 0.97g on the skidpad.
5. VTG TURBO & BOOST MANAGEMENT
The 991 Turbo was the first gas (as opposed to diesel) road car to use Variable Geometry Turbos. As Porsche describes it:
The variable turbine geometry makes it possible to simulate the cross sections of the respective optimum charger size via guide vanes positioned in the exhaust stream. At lower speeds, the vanes close in order to form the small air gaps that are found in a small turbocharger. The guide vanes remain in this position until the desired charging pressure is reached. If the exhaust flow continues to rise as the speed increases, the VTG guide vanes increase the throughflow and thereby regulate the charging pressure. In addition, the variable geometry of the charger is calculated to ensure that it is able to handle even the maximum exhaust mass that can occur.
6. LOAD BEARING BRACKET
In testing, Porsche found that the boost pressure was causing a strain on the opposing intake runners. Boost was pushing them apart. This minimalist bracket provided just enough tensile strength to keep things together and make sure the seats and gaskets stayed in check.