Turbo fuel stratified injection

Turbo fuel stratified injection (TFSI) is a trademark of the Volkswagen Group for a type of forced-aspiration ("turbo") engine where the fuel is pressure-injected straight into the combustion chamber in such a way as to create a stratified charge. FSI direct injection technology increases the torque and power of spark-ignition engines, makes them as much as 15 percent more economical and reduces exhaust emissions.[1]

Advantages

Some advantages of TFSI engines:

  1. Better fuel distribution and better fuel charge inside the combustion chamber
  2. During the injection process the fuel gets evaporated, cooling the cylinder chamber
  3. Cooling effect of the pressurized fuel allows for use of a lower octane fuel leading to a cost savings for the end user
  4. Higher compression ratios, which translates into more power
  5. Increased fuel combustion efficiency
  6. Higher power during pick-up of vehicle.

Disadvantages

  1. Huge rise of number of emitted exhaust particles
  2. Carbon build up behind the intake valves. Since fuel is directly injected inside the combustion chamber, it never gets a chance to wash any contaminants behind the valves. This results in excessive carbon build up over time, hindering performance. Some cars (like the Toyota 2GR-FSE engine in the Lexus IS) combine direct injection with traditional multi port fuel injection to ameliorate this problem.
  3. More expensive - much higher pressure fuel pumps are required to inject the fuel directly into the cylinder. This requires fuel pressures of up to 200 bar, much greater than a traditional multiport injection setup.[2] See direct injection.

References

  1. ↑ "Archived copy". Archived from the original on April 28, 2009. Retrieved July 24, 2009.
  2. ↑ http://products.bosch-mobility-solutions.com/en/de/powertrain/powertrain_systems_for_passenger_cars_1/direct_gasoline_injection/direct_gasoline_injection_23.html
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