Some Audi inline 5 20VT history:
In the beginning there was the inline 10V 5 cylinder used in the early Audi 100s (before 1980). Then there was the 10V turbo 5 cylinder engine used in Audi 100 sedans and then the first Audi quattros. By 1984, the first twin-cam 20 valve turbo engine, the "KW", showed up in the Sport quattro.
The KW engine was, to quote George Achorn, "..a double overhead cam 20-valve cross-flow version of Audi's stalwart 5-cylinder engine design, though with an alloy block - a 51-lb. savings over the cast iron version. This was the first Audi 5-cylinder to employ 4-valves per cylinder or a cross-flow design. Mated to this updated engine is a sizable KKK-K27 turbo, Bosch LH Jetronic injection and Langerrer & Reich intercooler, as was found in earlier Quattro race cars. Running a compression ratio of 8:1, the engine pumped out 306-bhp at 6700 rpm in the road going versions of the car like our test vehicle, though full rally-spec cars were known for more like 600-bhp. Torque was a healthy 258 lb-ft, and peaked at 3700 rpm. All told, the Sport quattro rates in at nearly 143-bhp per liter, a very exclusive club by today's standards, much less that of 1985."
The Sport Q was built for homogulation purposes with a total of 214 cars built (officially). Here is the Sport Q engine, showing the intake manifold on the left side of the engine (with the throttle body at the front of the intake manifold) and the exhaust manifold on the right side.
Here it is again, showing more detail, including the "DOHC, 4V" designation (no idea what the indent in the cam cover between 1 and 2 is all about). The intake cam is gear driven off the exhaust cam.
Here is the "same" engine in Group B Rallye car dressing (Note: now the indent in the cam cover is gone (??)):
Photo courtesy of Fourtitude
While the Type 44 200 TransAm cars were campaigned in 1988 with 10V turbo engines, when the TransAm rule changes lead Audi to switch to the IMSA circuit for 1989, the new Audi 90 GTO IMSA engine was a twin-cam turbo 20V engine, at least somewhat related to the Sport Q engine (but note the timing belt cover is lower than both cams so both were gear driven - good for relability but noisy for a civilian engine):
The first mass production Audi 20V turbo engine was the 3B for the 1990 200 20VT cars. The 3B was probably based mostly on the Sport Q KW engine and maybe partially on the IMSA GTO engine but obviously detuned and with chain-driven cams for use in the 200 20vt and the last years of the quattro (as the "RR"). The RR and the 3B are very similar. The RR shares some parts with the Sport Q KW so the RR-3B-KW lineage is there.
The 3B and the RR both had a distributor (with Hall Sender inside) driven off the intake cam, a single coil and spark plug wires. The intake manifold had the throttle body at the rear of the engine. The first 3Bs were built in March 1989 for installation in the 200 20VT (Type 44) sedans (and presumably the much rarer 200 20vt avants). The first RRs were built in August 1989 for the late run 1990 and 1991 quattro coupes. The first 3Bs for the S2 (Type 89/B3) coupes were built in Sept 1990. In North America, there were no RR quattros or S2 coupes. The US got the 200 20vt sedans and avants as 1991 model year vehicles. The first 3Bs engines used in the US-bound 200 20vts were built in May 1990 (just ahead of the 1991 model year start).
Here is an very nice 3B outside its engine bay (the spark plug wires are under the "20V turbo" cover) Note the intake piping:
While the Audi quattro coupes were no longer imported into North America after 1986 (87?), they were still made in the rest of the world. When Audi tried to kill the Audi quattro by bringing in the S2 coupe as a 1990 model with the 3B engine, there was a hue and cry to keep the Audi quattro in production. Audi relented and continued to build the quattro coupe with the RR 20vt engine until 1991, i.e. the 3B S2 and the RR quattro were available at the same time for awhile.
Here is a good example of an RR in a late run UrQ:
Photo Courtesy of Steve from Doncaster on the quattroforum.
The distributor and the single coil ignition on the 3B (and RR) was a limitation to more power. Use of a wide tip rotor might have also lead to "spark-hop" in the distributor which caused rod bending. For these reasons, the next progression was the AAN with five individual coil-on-plug coils and a cam sensor that was located behind the exhaust cam drive gear). This brought the horsepower up from 220 DIN hp to 230 DIN hp (227 SAE hp). The AAN was used in the C4 UrS4 and UrS6 sedans and avants from 1992 to 1997. The first AANs were built in August 1991 (for the 1992 model year UrS4s). Up to mid-February 1992, the early AANs had the G40 Cam sensor in vestigial "Tuna can" distributor, located where the 3B distributor was located.
Here is an AAN in a RHD 92 UrS4 avant in the UK (note: this one is missing the OE airbox/MAF cover and has the early AAN style cam cover and the single hump rad support/lock carrier):
Photo courtesy of Gary Bray (UnicomUrS4).
Here is an UrS6 engine bay showing an AAN with the ABY style cam cover and the OE airbox/MAF cover (note also the double humped rad support):
Photo courtesy of lliejk (Ed)
When it was time to update the S2 and expand to avants and sedans for the late 1993 model year, the sedans and avants got the B4 chassis but the S2 coupes stayed as B3/Type 89s. However, all of the S2s got a derivative of the AAN, the ABY, with the same five coil set-up as the AAN but with an same intake system very similar to the 3B. In contrast to the 3B having all v-belts for the accessory drives, the ABY has a poly-v belt for the alternator, (not really a serpentine belt since it only goes to one accessory) and separate v-belts for the hydraulic pump and A/C compressor. The ABY was used in the S2 coupes, avants and sedans, from mid-1993 on. The first ABYs were built in March 1993.
Here are a couple of ABY cut-aways, showing the 3B-style intake system but the AAN-style coil-on-plug "20V Turbo" coil pack cover:
Here is a photo of an early S2 ABY with the smooth top intake manifold:
Here is a later RHD ABY S2 with the later intake manifold with the outline of where a ADU-style logo could go on the top of the intake manifold. Note also the cam cover shape - same shape as the later UrS6 AAN cam covers)
The final derivative of the Inline 5 20vt was the ADU used in the RS2s (which were based on the B4 S2 avants). The ADU engine is based on the ABY (in turn based on the AAN) with an intake similar to the 3B but with a larger K24-7200 turbo, larger injectors, different MAF, different exhaust cam (and cam gear) and different exhaust manifold, all specified by Porsche (but added by Audi). With software changes, the ADU made 315 DIN hp.
Here is a photo of an ADU - note the intake manifold with the "Powered by Porsche" OE inscription:
ALL of the external ADU parts (with the exception of the intake manifold*) bolt on to the AAN, allowing tuners to take AANs (and ABYs) to about 380 hp without any internal changes.
The ADU and the ABY both use the same accessory drive belt configuration: a poly-v belt for the alternator and separate plain ole v-belts for the hydraulic pump and A/C compressor. The first ADUs were built in April 1994 (which is weird because the first RS2 VINs were assigned in March 1994 - might have to do with the way the engines and bodies were made in different locations and then assembled by Porsche at their Zuffenhausen factory).
* - the ADU intake will bolt onto an AAN but it doesn't make sense because the more effficient air flow is with the throttle body nearer the front of the engine, closer to the intercooler.
One reference:
http:\\12v.org\urs\AudiMagWinter9020vtengine.pdf
In the beginning there was the inline 10V 5 cylinder used in the early Audi 100s (before 1980). Then there was the 10V turbo 5 cylinder engine used in Audi 100 sedans and then the first Audi quattros. By 1984, the first twin-cam 20 valve turbo engine, the "KW", showed up in the Sport quattro.
The KW engine was, to quote George Achorn, "..a double overhead cam 20-valve cross-flow version of Audi's stalwart 5-cylinder engine design, though with an alloy block - a 51-lb. savings over the cast iron version. This was the first Audi 5-cylinder to employ 4-valves per cylinder or a cross-flow design. Mated to this updated engine is a sizable KKK-K27 turbo, Bosch LH Jetronic injection and Langerrer & Reich intercooler, as was found in earlier Quattro race cars. Running a compression ratio of 8:1, the engine pumped out 306-bhp at 6700 rpm in the road going versions of the car like our test vehicle, though full rally-spec cars were known for more like 600-bhp. Torque was a healthy 258 lb-ft, and peaked at 3700 rpm. All told, the Sport quattro rates in at nearly 143-bhp per liter, a very exclusive club by today's standards, much less that of 1985."
The Sport Q was built for homogulation purposes with a total of 214 cars built (officially). Here is the Sport Q engine, showing the intake manifold on the left side of the engine (with the throttle body at the front of the intake manifold) and the exhaust manifold on the right side.
Here it is again, showing more detail, including the "DOHC, 4V" designation (no idea what the indent in the cam cover between 1 and 2 is all about). The intake cam is gear driven off the exhaust cam.
Here is the "same" engine in Group B Rallye car dressing (Note: now the indent in the cam cover is gone (??)):
Photo courtesy of Fourtitude
While the Type 44 200 TransAm cars were campaigned in 1988 with 10V turbo engines, when the TransAm rule changes lead Audi to switch to the IMSA circuit for 1989, the new Audi 90 GTO IMSA engine was a twin-cam turbo 20V engine, at least somewhat related to the Sport Q engine (but note the timing belt cover is lower than both cams so both were gear driven - good for relability but noisy for a civilian engine):
The first mass production Audi 20V turbo engine was the 3B for the 1990 200 20VT cars. The 3B was probably based mostly on the Sport Q KW engine and maybe partially on the IMSA GTO engine but obviously detuned and with chain-driven cams for use in the 200 20vt and the last years of the quattro (as the "RR"). The RR and the 3B are very similar. The RR shares some parts with the Sport Q KW so the RR-3B-KW lineage is there.
The 3B and the RR both had a distributor (with Hall Sender inside) driven off the intake cam, a single coil and spark plug wires. The intake manifold had the throttle body at the rear of the engine. The first 3Bs were built in March 1989 for installation in the 200 20VT (Type 44) sedans (and presumably the much rarer 200 20vt avants). The first RRs were built in August 1989 for the late run 1990 and 1991 quattro coupes. The first 3Bs for the S2 (Type 89/B3) coupes were built in Sept 1990. In North America, there were no RR quattros or S2 coupes. The US got the 200 20vt sedans and avants as 1991 model year vehicles. The first 3Bs engines used in the US-bound 200 20vts were built in May 1990 (just ahead of the 1991 model year start).
Here is an very nice 3B outside its engine bay (the spark plug wires are under the "20V turbo" cover) Note the intake piping:
While the Audi quattro coupes were no longer imported into North America after 1986 (87?), they were still made in the rest of the world. When Audi tried to kill the Audi quattro by bringing in the S2 coupe as a 1990 model with the 3B engine, there was a hue and cry to keep the Audi quattro in production. Audi relented and continued to build the quattro coupe with the RR 20vt engine until 1991, i.e. the 3B S2 and the RR quattro were available at the same time for awhile.
Here is a good example of an RR in a late run UrQ:
Photo Courtesy of Steve from Doncaster on the quattroforum.
The distributor and the single coil ignition on the 3B (and RR) was a limitation to more power. Use of a wide tip rotor might have also lead to "spark-hop" in the distributor which caused rod bending. For these reasons, the next progression was the AAN with five individual coil-on-plug coils and a cam sensor that was located behind the exhaust cam drive gear). This brought the horsepower up from 220 DIN hp to 230 DIN hp (227 SAE hp). The AAN was used in the C4 UrS4 and UrS6 sedans and avants from 1992 to 1997. The first AANs were built in August 1991 (for the 1992 model year UrS4s). Up to mid-February 1992, the early AANs had the G40 Cam sensor in vestigial "Tuna can" distributor, located where the 3B distributor was located.
Here is an AAN in a RHD 92 UrS4 avant in the UK (note: this one is missing the OE airbox/MAF cover and has the early AAN style cam cover and the single hump rad support/lock carrier):
Photo courtesy of Gary Bray (UnicomUrS4).
Here is an UrS6 engine bay showing an AAN with the ABY style cam cover and the OE airbox/MAF cover (note also the double humped rad support):
Photo courtesy of lliejk (Ed)
When it was time to update the S2 and expand to avants and sedans for the late 1993 model year, the sedans and avants got the B4 chassis but the S2 coupes stayed as B3/Type 89s. However, all of the S2s got a derivative of the AAN, the ABY, with the same five coil set-up as the AAN but with an same intake system very similar to the 3B. In contrast to the 3B having all v-belts for the accessory drives, the ABY has a poly-v belt for the alternator, (not really a serpentine belt since it only goes to one accessory) and separate v-belts for the hydraulic pump and A/C compressor. The ABY was used in the S2 coupes, avants and sedans, from mid-1993 on. The first ABYs were built in March 1993.
Here are a couple of ABY cut-aways, showing the 3B-style intake system but the AAN-style coil-on-plug "20V Turbo" coil pack cover:
Here is a photo of an early S2 ABY with the smooth top intake manifold:
Here is a later RHD ABY S2 with the later intake manifold with the outline of where a ADU-style logo could go on the top of the intake manifold. Note also the cam cover shape - same shape as the later UrS6 AAN cam covers)
The final derivative of the Inline 5 20vt was the ADU used in the RS2s (which were based on the B4 S2 avants). The ADU engine is based on the ABY (in turn based on the AAN) with an intake similar to the 3B but with a larger K24-7200 turbo, larger injectors, different MAF, different exhaust cam (and cam gear) and different exhaust manifold, all specified by Porsche (but added by Audi). With software changes, the ADU made 315 DIN hp.
Here is a photo of an ADU - note the intake manifold with the "Powered by Porsche" OE inscription:
ALL of the external ADU parts (with the exception of the intake manifold*) bolt on to the AAN, allowing tuners to take AANs (and ABYs) to about 380 hp without any internal changes.
The ADU and the ABY both use the same accessory drive belt configuration: a poly-v belt for the alternator and separate plain ole v-belts for the hydraulic pump and A/C compressor. The first ADUs were built in April 1994 (which is weird because the first RS2 VINs were assigned in March 1994 - might have to do with the way the engines and bodies were made in different locations and then assembled by Porsche at their Zuffenhausen factory).
* - the ADU intake will bolt onto an AAN but it doesn't make sense because the more effficient air flow is with the throttle body nearer the front of the engine, closer to the intercooler.
One reference:
http:\\12v.org\urs\AudiMagWinter9020vtengine.pdf
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