Tumble Port

Tumble Port

Efficient mixing of air and fuel is also supported in the new 911 Turbo by the special shape of the intake ports in the cylinder head. The tumble port used here for the first time is characterized by narrowing of the intake ports upstream of the valve seat. This port form accelerates the air flowing into the cylinder and sets it in a tumbling motion, allowing the injected fuel to mix even better with the intake air. The special port geometry of the intake ports creates different inflow speeds via the circumference of the valve. This results in air tumble in the cylinder, thereby providing optimum mixture formation for combustion.







A tumble port is characterized by:

- Narrowing of the intake ports upstream of the valve seat
- Inflowing air is accelerated in the cylinders with a tumbling motion
- Improved mixing of fuel and air

Advantages:

- More uniform combustion
- Smoother engine running
- Higher thermal efficiency of the fuel quantity used (reduced fuel consumption)

Intake System - Deceleration Air Control







In the turbo engine, the intake air is routed from the filter housing via the separate air ducts on the left and right directly to the intake side of the respective turbocharger. Downstream of the compressor, the compressed and heated air is cooled in the charge air coolers on the left and right and then routed together again upstream of the electronic throttle. Cooling of the charge air ensures high cylinder charging and reduced component temperatures. In order to adapt to the higher performance figures, the turbochargers for the new 911 Turbo have improved flow properties and the compressor wheel has been enlarged.

The diverter valves have also been modified. These valves relieve excess boost pressure from the pressure side to the suction side of the turbochargers when the throttle valve is closed quickly. In the predecessor, they were integrated directly in the turbochargers. The diverter valves in the new 911 Turbo DFI are located immediately upstream of the throttle valve. This position allows improved flow behaviour in the exhaust system.







Deceleration air control is activated in deceleration mode. For this purpose, a connection is produced between the pressure side and suction side of the intake air on each turbocharger. Activation takes place when the DME control unit switches the electric switching valve (ES). The vacuum then opens the diaphragm cells (MD) for deceleration air control on the left and right. Deceleration air control ensures better engine response for acceleration after an deceleration phase since the turbocharger speed does not drop to the same extent. In addition, the mechanical loads and noise are reduced.