The plenum is the piece that goes between the Cayman throttle body and the intake runners. The factory piece is a long black plastic tube with a divider down the middle. There are aftermarket replacements which are designed to allow the air to flow easier/faster into the engine and increase horsepower and torque.

Direct Fuel Injection (DFI), is a new technology that Porsche states can cut fuel consumption by up to 15 percent, while increasing power by up to 13 percent. DFI cuts emissions by warming up the catalytic converter more quickly, and ensures a sharper throttle response. Better for your right foot - and the planet, then.

DFI allows much more precise measurement of fuel supply and injection at pressures up to 120 bar; it has numerous combustion modes, with different cycles for cold-starting, low-speed driving and performance driving.

As the name suggests, DFI injects fuel directly into the individual combustion chambers, instead of the intake manifold. The injector valves have an electromagnetic mechanism that controls each injection with astonishing precision, while a high-pressure pump provides the necessary pressure—up to 1,740 psi—to accompany the rapid fire of the fuel injection.

Precise geometry of the injector’s position and its spray pattern is a key factor in helping to improve power, torque and emissions of the engines. The specific placement of the fuel as it enters each chamber creates a swirl that improves the air/fuel mixture, and therefore the overall combustion process.

At engine speeds up to 3500 rpm, a double-injection process is used. In this mode, the required fuel volume is delivered in two successive injections per working stroke. The resulting benefits include faster catalyst warm-up and increased torque in the upper load range.

By forming the air/fuel mix directly in the combustion chamber, DFI contributes to engine cooling. As a result, it is possible to increase the compression ratio and with it the power and efficiency of the engine.

The direct injection process is continuously adjusted. The engine management system reads changes to throttle inputs and performance requirements and, as you drive, the air/fuel mix is monitored and adapted as required. Oxygen sensor circuits within the exhaust system provide accurate emissions control.

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