General Information About DFI Engines
General Information About DFI Engines
911 Carrera direct fuel injection (DFI)
A totally redesigned generation of 3.6 and 3.8-liter engines with DFI is used for the 911 Carrera models from model year 2009:
Porsche is using direct fuel injection (DFI) for the first time in this new generation of engines for the Porsche sports car models. DFI offers numerous advantages compared to intake manifold injection. The main objective here is to achieve an air/fuel mixture adapted specifically to the respective operating and load states of the engine using an injection system and mixture formation. This provides the perfect solution for meeting the various demands relating to economy, power, vehicle handling and emissions.
With direct fuel injection, the fuel is injected directly into the combustion chamber and mixture formation takes place almost completely in the combustion chamber.
Development objectives for the new DFI flat-six engines:
- Increase in power and torque over the entire rpm range
- Better responsiveness
- Much lower fuel consumption values and CO2 emissions combined with greater performance
The illustration shows the 911 Carrera 3.6-liter DFI engine with intake system and exhaust system.
These objectives have been achieved thanks to the following enhancements and technologies of the new 3.6 and 3.8-liter engines:
- Use of direct fuel injection (DFI)
- Engine control unit Siemens EMS SDI 3.1
- DFI-specific cylinder heads
- DFI-specific recessed pistons
- Higher compression ratio
- Electronic demand-controlled oil pump
- New intake systems (adapted specifically for each engine)
- New exhaust systems (adapted specifically for each engine)
The most important technical components of the direct fuel injection system are:
- The fuel low-pressure system
- The fuel high-pressure system
- The fuel high-pressure pump with flow control valve
- The fuel high-pressure line and the fuel distribution pipes to banks 1 and 2
- The fuel pressure sensor
- The fuel injectors (high-pressure fuel injectors)
911 Carrera DFI engines
The considerably higher performance values of the new engines were achieved mainly through the use of direct fuel injection (DFI), modification of the intake and exhaust systems and improvements within the engines. It was possible to increase the engine power and torque and reduce consumption and emissions without changing the displacement. Depending on the model, it was possible to reduce the fuel consumption and CO2 emissions despite the enhanced performance while retaining the same displacement. The country-specific data records of the new DME control unit EMS SDI 3.1 have been specially adapted to suit direct fuel injection and the modified engine specifications of 3.6- and 3.8-liter engines.
- DFI - direct fuel injection
- Revised intake system
- Enhanced exhaust system
- Improvement measures within the engine
911 Carrera 3.6-liter DFI engine
The power of the new 3.6-liter flat-six engine was increased by 20 bhp to 345 bhp (254 kW) at 6,500 rpm and the torque could be boosted by 20 Nm to 390 Nm at 4,400 to 5,800 rpm. The compression ratio was raised from 11.3 : 1 to 12.5 : 1. The idle speed was set to 680 ± 80 rpm and the maximum engine speed was limited to 7,500 rpm.
Pistons
The piston recess on the piston crown (shown in grey) is specifically designed to suit the characteristics of the 3.6- and 3.8-litre engines during late injection with high-pressure stratified charge ignition and during the catalytic converter heating phase. The higher compression ratio realised as a result of DFI serves to enhance performance and optimize fuel consumption.
911 Carrera S 3.8-liter DFI engine
The power of the new 3.8-liter Carrera S models was increased by 30 bhp to 385 bhp (283 kW) at 6,500 rpm; the torque could also be boosted by 20 Nm to 420 Nm at 4,400 to 5,800 rpm. The compression ratio was raised from 11.8 : 1 to 12.5 : 1. The idle speed was set to 680 ± 80 rpm and the maximum engine speed was limited to 7,500 rpm.