Audi 4.2-liter V8 FSI Engine SSP 921603

Online PDF Audi 4.2-liter V8 FSI Engine SSP 921603

The first member of the current Audi V family of engines was the 3.2-liter V6 FSI engine. Special features of the Audi V-engine family are the 90-degree angle between the cylinder banks and the 90 mm spacing between the cylinders. 

The 4.2-liter V8 FSI engine is also a member of this family. It is available in two versions – a comfort-oriented version (used for the first time in the Audi Q7) and a sporty high-revving version for the new RS4. A 5.2L V10 FSI will also be available in the near future.

The 4.2-liter V8 FSI engine is supplied in the new Audi Q7 and RS4. In the future, the engine will be used in the Audi A6 and A8.
The following main objectives were set for the development of the Audi Q7 engine:

  1. High specific engine power: 
  2. 350 bhp out of 4.2 liters (15 bhp more than MPI 
  3. engines)
  4. High torque: 325 lb. ft. out of 4.2 liters 
  5. Reduction of fuel consumption by approximately 5 % 
  6. (at 2000 rpm and 2 bar)
  7. Short and compact design 
  8. Modular engine concept based on the V6 FSI engine 
  9. for V8 and V10 FSI 
  10. High idling quality 
  11. High standard of comfort with regard to acoustics and 
  12. running quality 
  13. Low engine weight 
  14. Off-road capability of Audi Q7 engine

The cylinder crankcase has a closed-deck design, which is stronger than the open-deck design. In an open-deck cylinder block, the water jacket for cooling the cylinders is open at the top. The cylinder crankcase is made of a low-pressure gravity diecast aluminum-silicon alloy, is hypereutectic* and has a silicon content of 17 % (AlSi17Cu4Mg).

The cylinder crankcase underwent special heat treatment to increase its strength. The cylinder liners are mechanically stripped.
The cylinder crankcase of the high-revving engine was machined to higher specifications due to the higher stresses in this component. To minimize warping of the cylinder manifolds, the crankcase is honed under stress. For this purpose, a honing template is attached to the crankcase before the honing process in order to simulate the warping of the bolted-on cylinder manifold.

Technical Features

  1. Fuel Straight Injection 
  2. Roller cam rocker arms with hydraulic lifters 
  3. Chain drives for camshafts and accessories 
  4. Variable camshaft adjustment for intake and exhaust 
  5. camshafts 
  6. Two-stage magnesium variable inlet manifold with 
  7. integrated tumble flap (not fitted in RS4)
  8. Drive-by-wire throttle control (For compliance with exhaust emission standards LEV II)

The main technical differences between the base engine and the high-revving engine lie in the following:

  1. Crankshaft/connecting rods/pistons Timing gear 
  2. Cylinder head 
  3. Oil supply 
  4. Engine cooling 
  5. Intake path 
  6. Exhaust system 
  7. Engine management

For an exact description of the differences, please refer to the relevant sections in this SSP.

Online PDF Audi 4.2-liter V8 FSI Engine SSP 921603