Audi ADU Specifications
| Engine Model: Audi ADU |
| Engine Type: 4-cycle 5-cylinder DOHC 20-valve turbocharged liquid-cooled gasoline |
| Total Displacement: 135.9 cu.in (2.22 L) |
| Rated Engine Power: 311 Hp (232 kW) at 6500 rpm |
| Fuel System Type: Sequential multi-point fuel injection (MPFI) |
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The Audi ADU engine is the 2.2-liter,
five-cylinder, turbocharged and intercooled powerplant developed
exclusively for the Audi RS 2 Avant. Created through a landmark
collaboration between Audi and Porsche, this engine represents the
pinnacle of the 20-valve inline-five series and is the direct
predecessor to the legendary 1.8T and 2.7T engines. Based on the Audi
S2's AAN block, the ADU received extensive modifications by Porsche,
including a larger KKK K24/27 7200 turbocharger, a more efficient
intercooler, revised intake and exhaust manifolds, and
Porsche-calibrated Bosch engine management.
The result is an engine delivering 315 PS, with immense mid-range torque
and a surprisingly linear power delivery for a large turbocharged engine
of its time. The ADU established the blueprint for the modern
high-performance Audi estate, combining robust engineering with a unique
character defined by its five-cylinder soundtrack and formidable thrust.
Its over-engineered components and conservative tuning have granted it
exceptional longevity and tunability.
Engine Type: Inline-5 cylinder, liquid-cooled, turbocharged and
intercooled, gasoline fuel injection.
Displacement: 2226 cc (2.226 L) / 135.9 cu.in.
Bore x Stroke: 81.0 mm x 86.4 mm / 3.19 in x 3.40 in.
Compression Ratio: 9.3:1. Firing Order: 1-2-4-5-3.
Direction of Rotation: Clockwise (viewed from the front/flywheel end).
Maximum Power Output: 232 kW (315 PS) at 6500 rpm. Imperial: 311 Hp at
6500 rpm.
Maximum Torque Output: 410 Nm at 3000 rpm. Imperial: 302 lb-ft (lb-ft)
at 3000 rpm.
Fuel Requirement: High-octane unleaded petrol, 98 RON (93 AKI) minimum.
Emission Standards Compliance: Euro 1.
Material: High-strength cast iron with closed-deck design.
Construction: Closed-deck block with six main bearing supports. Features
cross-bolted main bearing caps for maximum rigidity under high cylinder
pressure. The block is shared with the Audi S2/S4/S6 (AAN) but features
selected strength enhancements.
Crankshaft: Forged steel crankshaft. Main bearing journal diameter: 65.0
mm / 2.559 in. Crankpin journal diameter: 54.0 mm / 2.126 in.
Pistons: Cast aluminum alloy pistons (Mahle) with a specific dish
profile for the 9.3:1 compression ratio. Pistons are oil-jet cooled.
Connecting Rods: Forged steel connecting rods.
Material: Aluminum alloy.
Head Construction: Dual overhead camshafts (DOHC), 20-valve design (4
valves per cylinder). Camshafts are driven by a single toothed timing
belt.
Valve Arrangement: Pent-roof combustion chamber. Valves are actuated via
bucket tappets with shims for clearance adjustment. This is an
interference engine. Variable Valve Timing: None.
Valve Diameters: Intake: 34.0 mm / 1.339 in. Exhaust: 30.0 mm / 1.181
in.
Injection Type: Sequential multi-port fuel injection (MPFI).
Engine Management: Bosch Motronic M2.3 (Porsche-specific calibration).
This system integrates fuel injection, ignition timing, and boost
control.
Fuel Delivery: Dual in-tank electric fuel pumps supply the fuel rail.
Fuel Rail and Injectors: Five Bosch EV1 315 cc/min fuel injectors.
Turbocharger: KKK K24/27 7200 turbocharger with an integrated wastegate.
This is a larger hybrid unit compared to the K24 7000 in the S2.
Intercooler: Air-to-air intercooler mounted in the front-left bumper
area, with specific ducting for efficient cooling. Throttle Body: 70mm
diameter throttle body.
Type: Pressure-fed, full-flow filtration with a gear-type oil pump. The
system includes an oil cooler.
Oil Pump: Gear-type pump, driven by the crankshaft.
Oil Filter: Cartridge-type, mounted on the front of the engine block.
Oil Cooler: Engine oil cooler (oil-to-coolant) integrated into the
filter housing.
Oil Capacity (including filter): 5.5 L / 5.8 US qt.
Recommended Oil Grade: Full synthetic engine oil meeting VW standard 501
01 or 502 00. Viscosity: 5W-40 or 10W-60. Operating Oil Pressure: 2.0
bar at hot idle, 4.0 - 5.0 bar at 2000 rpm. Imperial: 29 psi (idle), 58
- 73 psi (2000 rpm).
Type: Pressurized, single-circuit system with an auxiliary electric fan
for the intercooler.
Water Pump: Centrifugal pump, driven by the timing belt.
Thermostat: Wax pellet type, opening temperature 87°C (189°F).
Coolant Capacity: 8.5 L / 9.0 US qt (entire system).
Coolant Type: VW G12 (pink) ethylene glycol-based antifreeze.
Electrical System: 12-volt negative ground. 120-amp alternator.
Ignition System: Distributorless ignition system (DIS) with a dual-spark
ignition coil pack, controlled by the Bosch Motronic ECU.
Engine Management: Bosch Motronic M2.3 as stated, featuring a hot-wire
mass air flow (MAF) sensor and a knock sensor for each cylinder bank.
Exhaust System: Stainless steel exhaust manifold and a low-restriction
catalytic converter and exhaust system.
Overall Length: 650 mm / 25.6 in.
Overall Width: 700 mm / 27.6 in.
Overall Height: 680 mm / 26.8 in.
Dry Weight: 160 kg / 353 lbs.
Engine Oil Change Interval: Every 10,000 km or 12 months. Severe
service: 5,000 km or 6 months. Imperial: 6,200 miles / 3,100 miles. Oil
Filter Change: Every oil change. Fuel Filter Change: Every 60,000 km
(37,300 miles). Air Filter Change: Every 30,000 km (18,600 miles) or as
inspected. Timing Belt Replacement: This is an interference engine.
Replace the timing belt, tensioner, idler rollers, and water pump every
60,000 km (37,300 miles) or 5 years without exception.
Spark Plug Replacement: Use specified copper-core plugs (e.g., Bosch
FR5DPP) every 15,000 km (9,300 miles). Coolant Replacement: Every 2
years. Valve Clearance Adjustment: Check and adjust (via shim
replacement) every 60,000 km (37,300 miles). Clearance (cold): Intake:
0.15-0.25 mm (0.006-0.010 in). Exhaust: 0.25-0.35 mm (0.010-0.014 in).
Cylinder Head Bolts: Torque-to-yield (TTY). Tighten in sequence: Step 1:
40 Nm (30 lb-ft). Step 2: +90° turn. Step 3: Final +90° turn. Bolts are
single-use.
Main Bearing Cap Bolts (Vertical): 65 Nm (48 lb-ft) + 90° turn.
Main Bearing Cap Bolts (Lateral): 20 Nm (15 lb-ft) + 90° turn.
Connecting Rod Cap Bolts: 30 Nm (22 lb-ft) + 90° turn (replace bolts).
Spark Plugs: 30 Nm (22 lb-ft).
Oil Drain Plug: 30 Nm (22 lb-ft).
Turbocharger to Manifold Nuts: 35 Nm (26 lb-ft).
Wheel Bolts: 120 Nm (89 lb-ft).
The Audi ADU engine was developed for and installed in one specific
vehicle: Audi RS 2 Avant (1994-1995): A limited-production (2,891 units)
high-performance estate car, assembled at the Porsche plant in
Zuffenhausen, Germany. The ADU engine, in conjunction with the
Porsche-enhanced chassis and braking system, defined the "fast estate"
segment and remains a highly sought-after collector's item.
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