S
SkyPup
Guest
THE DEVELOPMENT OF THE VOLKSWAGEN TURBOCHARGED DIRECT INJECTION (TDI) DIESEL ENGINES
This story is about the development of the first diesel engines at VOLKSWAGEN AND AUDI, which led to the first totally electronically controlled turbocharged diesel engine produced by Audi for incorporation in the AUDI 100 passenger car in 1990. This 5-cylinder AUDI TDI is the forerunner of the modern day Volkswagen TDI. The story covers parts of the early development of the first passenger car diesel engines leading up to the AUDI 5-cylinder. This story will be continued and updated as time goes on. Future installments will include the developments made through the production of the A3 TDI engine as well as the A4 TDI in the future, including the technological achievements of direct high pressure fuel injection and electronic vehicle management.
In the fall of 1976, Volkswagen introduced its first 4-cylinder Diesel engine, a swirlchamber design with a stroke of 80mm and a bore of 76.5mm, giving a displacement of 1471cc. The nominal power was 50HP at 5,000 rpm. Two years later, in 1978, the development of a 5 and 6-cylinder Diesel engine was completed. All 4,5,and 6 cylinder Diesels used the same combustion system. Thus, in addition to the powerplants for the Volkswagen Rabbit and Dasher vehicles, Diesel engines became available for the AUDI 5000 and the Volkswagen Truck. Since 1979, the 6-cylinder Diesel engine has been sold to VOLVO for a passenger car application.
In the fall of 1980 the engine displacement of the 4-cylinder was increased by lengthening the engine stroke from 80.0 to 86.4mm. Nominal power was increased to 40Kw or 54HP at 4,800 rpm with the maximum torque of l02Nm at 2,000 rpm. At this time, the longer stroke required a new connecting rod design and the distance between the connecting rod bolts was increased to 61.5mm. The piston pin diameter was also increased from 22 to 24mm. The small end bearing became a common part with the future 5 and 6—cylinder Diesel engines.
The last development of the naturally aspirated Diesel engine was concluded in early 1981 with an application to the Volkswagen Transporter and MicroBus. Engine power had been changed to 37Kw at 4,200 rpm. The demand for this naturally aspirated Diesel engine increased significantly so that in the first six months of 1981, 2,600 naturally aspirated Diesel engines were produced every day which represented 40% of the total production of water cooled engines in the Volkswagen Corporation.
MAIN DESIGN FEATURES:
The 4-cylinder Turbocharged Diesel Engine was designed as the powerplant for 5 vehicle models of VOLKSWAGEN AUDI production. The engine is transversely mounted in the Rabbit and Jetta vehicles. The engine is mounted longitudinally across the front axle in the Dasher, Quantum, and Audi 4000. Because of different space restrictions in the engine compartments, the turbocharger unit is mounted in two different locations. The power and torque are identical in both instances, nominal power is 51Kw or 7OHP at 4,500 rpm with maximum torque of 133Nm at 2,600 rpm. The engine displacement of 1599cc results from a bore of 76.5mm and a stroke of 86.4mm. The compression ratio is 23:1.
The turbocharger unit is adapted to small displacement Diesel engines. Turbochargers from Garrett Air Research and Kuhnle Koop and Kausch (KKK) are used. The turbine housing material has been optimized for the high exhaust temperatures encountered. In the case of excessive boost pressure, the wastegate opens and the turbine receives only a portion of the hot exhaust gases while the remainder flow directly into the exhaust pipe. As a result, turbine and impeller speed are reduced and the designed boost pressure is maintained. Turbocharger boost pressure begins to develop at 1,400 rpm and is regulated with a maximum wastegate movement of 10mm. At 0.6 bar the wastegate actuator remains closed, at 0.8 bar the wastegate actuator is opened one half maximum at 5mm, and at 1.0 bar the wastegate actuator is opened the full 10mm, thereby regulating the boost pressure to about 0.8 bar throughout the turbochargers operational range. Boost pressure development of the turbocharger allows a Pressure Ratio (P2/Pi) of 1.1 at 1,400 rpm, 1.3 at 2,000 rpm, 1.5 at 3,000 rpm, and 1.7 maximum at 4,000 rpm. This corresponds to a full load boost pressure of 0.8 bar from 2,220 rpm to 3,750 rpm. Being as the turbo boost pressures were held to an average max. of 0.8 bar, a charge air cooler (intercooler) was not needed to lower the intake air temperature. Turbine inlet and exhaust temperatures did not exceed 820 degrees C. at maximum load.
The oil circuit had to be adapted to the specific needs of the engine because of the higher thermal loading due to the turbocharger. In addition to conventional pressurized lubrication, oil lines with upwards directed jets are mounted in the crankcase at each cylinder to provide additional cooling of the piston bottoms. Also, the oil cooling and lubricating the turbocharger flows back into the oil pan via a flexible tube. Oil pump capacity has been increased 15% as well. The special oil cooling adapted to the piston bottoms has resulted in lowering the critical piston temperatures by approximately 30 degrees C. Because of the turbocharging also causing higher exhaust valve temperatures about 100-150 degrees C. higher than normal aspirated Diesel, a better exhaust valve material was applied as well as for the valve seats.
An increase in stiffness between the cylinder head and the engine block as well as a change in the tightening procedure were essential modifications for the turbochargered Diesel engine. Cylinder head bolts are increased from 11mm to 12mm along with deck thickness. Extensive testing was done to optimize the cylinder head gasket in conjunction with the cylinder block modifications. The cylinder head gasket has to give reliable sealing for combustion pressures up to 130 bar with a sealing land of only 6mm. The cylinder block and head were also designed to withstand combustion pressures of up to 130 bar. The limiting value for turbocharger boost pressure on a diesel engine is peak compression pressure, which has been limited to 130 bar on this engine.
This four cylinder VW AUDI TURBOCHARGED DIESEL engine was superceded by the AUDI 5-CYLINDER 2.5 LITER TURBO DIESEL in 1990 for introduction in the AUDI 100. This engine is the first engine to be built using electronically controlled turbocharged diesel engine management to include electronic throttle pedal and BOSCH VE VP-34 distributor fuel pump under control of the BOSCH ECU. On the AUDI 5-cylinder Turbo diesel a KKK K-16 turbocharger with integral wastegate ensured the buildup of boost pressures even at low operating rpms. This assisted in the good engine response to the accelerator. A charge air cooler (intercooler) was introduced to lower the intake air temperature due to higher boost pressures. The intercooler reduces intake air temperatures by a maximum of 70 degrees C. and its thermal efficiency has been established at 80% with only 80mbar pressure loss throughout.
------------------
99 JETTA TDI HERR WETTERAUER TORQUEMEISTER
98 KAFER WETT SPEKTAKULARE TURBOKOMPRESSOR
97 KTM 620 ADVENTURE RALLY PARIS-DAKAR SUPER THUMPER
ICH LEBE MEIN TECHORAD VW TDI'S MIT DIREKTEINSPRITZER TURBOKOMPRESSOR
This story is about the development of the first diesel engines at VOLKSWAGEN AND AUDI, which led to the first totally electronically controlled turbocharged diesel engine produced by Audi for incorporation in the AUDI 100 passenger car in 1990. This 5-cylinder AUDI TDI is the forerunner of the modern day Volkswagen TDI. The story covers parts of the early development of the first passenger car diesel engines leading up to the AUDI 5-cylinder. This story will be continued and updated as time goes on. Future installments will include the developments made through the production of the A3 TDI engine as well as the A4 TDI in the future, including the technological achievements of direct high pressure fuel injection and electronic vehicle management.
In the fall of 1976, Volkswagen introduced its first 4-cylinder Diesel engine, a swirlchamber design with a stroke of 80mm and a bore of 76.5mm, giving a displacement of 1471cc. The nominal power was 50HP at 5,000 rpm. Two years later, in 1978, the development of a 5 and 6-cylinder Diesel engine was completed. All 4,5,and 6 cylinder Diesels used the same combustion system. Thus, in addition to the powerplants for the Volkswagen Rabbit and Dasher vehicles, Diesel engines became available for the AUDI 5000 and the Volkswagen Truck. Since 1979, the 6-cylinder Diesel engine has been sold to VOLVO for a passenger car application.
In the fall of 1980 the engine displacement of the 4-cylinder was increased by lengthening the engine stroke from 80.0 to 86.4mm. Nominal power was increased to 40Kw or 54HP at 4,800 rpm with the maximum torque of l02Nm at 2,000 rpm. At this time, the longer stroke required a new connecting rod design and the distance between the connecting rod bolts was increased to 61.5mm. The piston pin diameter was also increased from 22 to 24mm. The small end bearing became a common part with the future 5 and 6—cylinder Diesel engines.
The last development of the naturally aspirated Diesel engine was concluded in early 1981 with an application to the Volkswagen Transporter and MicroBus. Engine power had been changed to 37Kw at 4,200 rpm. The demand for this naturally aspirated Diesel engine increased significantly so that in the first six months of 1981, 2,600 naturally aspirated Diesel engines were produced every day which represented 40% of the total production of water cooled engines in the Volkswagen Corporation.
MAIN DESIGN FEATURES:
The 4-cylinder Turbocharged Diesel Engine was designed as the powerplant for 5 vehicle models of VOLKSWAGEN AUDI production. The engine is transversely mounted in the Rabbit and Jetta vehicles. The engine is mounted longitudinally across the front axle in the Dasher, Quantum, and Audi 4000. Because of different space restrictions in the engine compartments, the turbocharger unit is mounted in two different locations. The power and torque are identical in both instances, nominal power is 51Kw or 7OHP at 4,500 rpm with maximum torque of 133Nm at 2,600 rpm. The engine displacement of 1599cc results from a bore of 76.5mm and a stroke of 86.4mm. The compression ratio is 23:1.
The turbocharger unit is adapted to small displacement Diesel engines. Turbochargers from Garrett Air Research and Kuhnle Koop and Kausch (KKK) are used. The turbine housing material has been optimized for the high exhaust temperatures encountered. In the case of excessive boost pressure, the wastegate opens and the turbine receives only a portion of the hot exhaust gases while the remainder flow directly into the exhaust pipe. As a result, turbine and impeller speed are reduced and the designed boost pressure is maintained. Turbocharger boost pressure begins to develop at 1,400 rpm and is regulated with a maximum wastegate movement of 10mm. At 0.6 bar the wastegate actuator remains closed, at 0.8 bar the wastegate actuator is opened one half maximum at 5mm, and at 1.0 bar the wastegate actuator is opened the full 10mm, thereby regulating the boost pressure to about 0.8 bar throughout the turbochargers operational range. Boost pressure development of the turbocharger allows a Pressure Ratio (P2/Pi) of 1.1 at 1,400 rpm, 1.3 at 2,000 rpm, 1.5 at 3,000 rpm, and 1.7 maximum at 4,000 rpm. This corresponds to a full load boost pressure of 0.8 bar from 2,220 rpm to 3,750 rpm. Being as the turbo boost pressures were held to an average max. of 0.8 bar, a charge air cooler (intercooler) was not needed to lower the intake air temperature. Turbine inlet and exhaust temperatures did not exceed 820 degrees C. at maximum load.
The oil circuit had to be adapted to the specific needs of the engine because of the higher thermal loading due to the turbocharger. In addition to conventional pressurized lubrication, oil lines with upwards directed jets are mounted in the crankcase at each cylinder to provide additional cooling of the piston bottoms. Also, the oil cooling and lubricating the turbocharger flows back into the oil pan via a flexible tube. Oil pump capacity has been increased 15% as well. The special oil cooling adapted to the piston bottoms has resulted in lowering the critical piston temperatures by approximately 30 degrees C. Because of the turbocharging also causing higher exhaust valve temperatures about 100-150 degrees C. higher than normal aspirated Diesel, a better exhaust valve material was applied as well as for the valve seats.
An increase in stiffness between the cylinder head and the engine block as well as a change in the tightening procedure were essential modifications for the turbochargered Diesel engine. Cylinder head bolts are increased from 11mm to 12mm along with deck thickness. Extensive testing was done to optimize the cylinder head gasket in conjunction with the cylinder block modifications. The cylinder head gasket has to give reliable sealing for combustion pressures up to 130 bar with a sealing land of only 6mm. The cylinder block and head were also designed to withstand combustion pressures of up to 130 bar. The limiting value for turbocharger boost pressure on a diesel engine is peak compression pressure, which has been limited to 130 bar on this engine.
This four cylinder VW AUDI TURBOCHARGED DIESEL engine was superceded by the AUDI 5-CYLINDER 2.5 LITER TURBO DIESEL in 1990 for introduction in the AUDI 100. This engine is the first engine to be built using electronically controlled turbocharged diesel engine management to include electronic throttle pedal and BOSCH VE VP-34 distributor fuel pump under control of the BOSCH ECU. On the AUDI 5-cylinder Turbo diesel a KKK K-16 turbocharger with integral wastegate ensured the buildup of boost pressures even at low operating rpms. This assisted in the good engine response to the accelerator. A charge air cooler (intercooler) was introduced to lower the intake air temperature due to higher boost pressures. The intercooler reduces intake air temperatures by a maximum of 70 degrees C. and its thermal efficiency has been established at 80% with only 80mbar pressure loss throughout.
------------------
99 JETTA TDI HERR WETTERAUER TORQUEMEISTER
98 KAFER WETT SPEKTAKULARE TURBOKOMPRESSOR
97 KTM 620 ADVENTURE RALLY PARIS-DAKAR SUPER THUMPER
ICH LEBE MEIN TECHORAD VW TDI'S MIT DIREKTEINSPRITZER TURBOKOMPRESSOR