TDI (Turbocharged Direct Injection) isVolkswagen Group's term for its current common rail direct injectionturbodiesel engine range that have anintercooler in addition to the turbo compressor.[1][2] TDI engines are used in motor vehicles sold by theAudi,Volkswagen,SEAT, andŠkodamarques, as well as in boat engines sold byVolkswagen Marine,[3][4][5] and industrial engines sold byVolkswagen Industrial Motor.[6][7]
The first TDI engine, a straight-five engine, was produced for the 1989 Audi 100 TDI sedan. In 1999,common rail fuel injection was introduced in the V8 engine used by the Audi A8 3.3 TDI Quattro. From 2006 until 2014, Audi successfully competed in theLMP1 category of motor racing using TDI engine-powered racing cars. TDI engines installed in 2009 to 2015 model year Volkswagen Group cars sold through 18 September 2015 had an emissionsdefeat device,[8][9] which activated emissions controls only during emissions testing. The emissions controls were suppressed otherwise, allowing the TDI engines to exceed legal limits on emissions.[10] Volkswagen has admitted to using the illegal device in its TDI diesel cars.[11]
TDI is the combination of two existing diesel engine technologies:
Most TDI engines also use anintercooler to lower the temperature (and therefore increase the density) of the compressed air before it enters the cylinder.[1][12] Similar technology has been used by other automotive companies, but the "TDI" marketing term is only used by Volkswagen Group andLand Rover. Volkswagen Group uses the termSDI (which stands for "Suction Diesel Injection") for itsnaturally aspirated (i.e. non-turbocharged) direct-injection diesel engines.
Prior to Volkswagen Group's first TDI engine, the first turbocharged diesel engine used in a passenger car was anindirect injection five-cylinder engine fitted to the 1978Mercedes-Benz 300SD (W116)300 SD sedan.[13] The first turbodiesel engine with direct injection was the 1986Fiat Croma 2.0 TD i.d. liftback sedan.[14]
Three years after the Fiat Croma, Volkswagen Group's first TDI engine was introduced in the 1989Audi 100 TDI sedan.[15][16] The Audi 100 was powered by theVolkswagen 2.5 R5 TDI straight-five engine which used an electronic distributorinjection pump (called "VerteilerPumpe" by Volkswagen) and two-stage direct injection. The initial version of this engine generated 88 kW (118 hp) at 3,250 rpm and 275 N⋅m (203 lb⋅ft) at 2,500 rpm.
TDI engines usingcommon rail fuel injection (usingpiezoelectric fuel injectors) were introduced with theVolkswagen Group 32v TDI V8 engine used in the 1999Audi A8 3.3 TDI Quattro, two years after the 1997Alfa Romeo 1562.4-L JTD became the first passenger car to use common rail injection.[17][18] In 1999, theVolkswagen 1.2-litre TDI won theInternational Engine of the Year categories for "1.0 to 1.4 litres" and "Best Fuel Economy".[19]
In 2000, a fuel system usingunit injectors (called "Pumpe Düse" by Volkswagen) began to replace the distributor injection pump systems (except for the V8 engine, which used common rail design).[1] In 2003, upgraded fuel injectors using a piezoelectric design began to replace the previous solenoid-operated unit injectors. Since 2009, most of the Volkswagen Group TDI engines have switched from unit injectors to common rail injection.
On 18 September 2015 theUS EPA andCalifornia Air Resources Board served notice to VW that approximately 480,000 VW and Audi automobiles equipped with 2.0 TDI engines sold in the US between 2009 and 2015 had an emissions compliancedefeat device installed.[8][9] The defeat device, in the form of specially craftedengine management unitfirmware, detects emissions testing conditions, and in such conditions will cause the vehicle to comply with emissions regulations by properly activating all emissions controls. However, under normal driving conditions, the emissions controls are suppressed, allowing the engine to produce more torque and get better fuel economy, at the expense of emitting up to 40 times morenitrogen oxides than allowed by law.[10] Such NOx emission levels are not in compliance with US regulations. VW has since admitted to these allegations, and said that the illegal software was in use in its diesel cars worldwide, affecting some 11 million vehicles.[11]
The first TDI engine used by Volkswagen Group for motor racing was in theAudi R10 TDI, which competed in theLe Mans Prototype (LMP) class of sports car racing. The Audi R10 recorded a victory on its debut at the 200612 Hours of Sebring race[20][21][22] and then at the 200624 Hours of Le Mans race, with both results being the first time that a diesel-powered car had won each race.[23][24][25] In the nine years from 2006 to 2014, the R10 and its successors (R15 andR18) won the 24 Hours of Le Mans eight times (the 2009 race was won by another diesel-powered car, thePeugeot 908 HDi FAP).
In theWorld Touring Car Championship (WTCC) racing series, theSEAT León TDI won the2008 championship and the2009 championship for drivers and manufacturers.[26][27] In 2008, the SEAT Leon TDI also competed in theBritish Touring Car Championship (BTCC) and became the first diesel car to win a round of the championship when it won the round atDonington Park.[28]
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