Audi CDRA Specifications
| Engine Model: Audi CDRA |
| Engine Type: 4-cycle 8-cylinder DOHC 32-valve liquid-cooled gasoline |
| Total Displacement: 254 cu.in (4.16 L) |
| Rated Engine Power: 366 Hp (273 kW) at 6800 rpm |
| Fuel System Type: Direct fuel injection |
____________________________________________________________________________________
The Audi CDRA is a 4.2-liter V8 FSI petrol engine
belonging to the EA896 family, specifically the third generation of this engine
series. Produced between 2009 and 2012, it served as the naturally aspirated
powerplant for the flagship Audi A8 (D4). The engine represents a significant
evolutionary step, incorporating high-pressure direct injection, a sophisticated
all-aluminum construction, and a high 12.5:1 compression ratio to achieve a
balance of refined power delivery and improved fuel efficiency.
As one of the final naturally aspirated V8s in the brand’s portfolio before the
industry-wide shift toward forced induction, the CDRA is noted for its smooth,
linear power curve, immediate throttle response, and distinctive acoustic
character. Its design emphasizes low-friction internal components and advanced
thermal management, establishing it as a high-water mark for Audi’s naturally
aspirated V8 engineering in the luxury sedan segment.
The CDRA engine is a naturally aspirated, four-stroke, spark-ignition unit with
a displacement of 4163 cc (254.0 cu.in). Its configuration is a 90-deg V8 with
dual overhead camshafts (DOHC) operating four valves per cylinder for a total of
32 valves. The bore and stroke measures 84.5 mm (3.33 in) by 92.8 mm (3.65 in),
contributing to an undersquare design that favors torque production in the
mid-range.
The compression ratio is set at 12.5:1. Peak
power output is 273 kW (371 PS / 366 hp) achieved at 6800 rpm, while
maximum torque reaches 445 Nm (328 lb-ft) at 3500 rpm. The firing order
is 1-5-4-8-6-3-7-2. The engine management system utilizes a Bosch MED
9.1.2 ECU.
The cylinder block is constructed from cast aluminum
alloy with cast-iron cylinder liners, a design choice that reduces overall
weight while providing a durable wear surface for the piston rings. This
open-deck block design incorporates a deep-skirt configuration for enhanced
rigidity under high cylinder pressures.
The bedplate design uses a two-piece lower crankcase to support the crankshaft,
which is a forged steel unit with four main bearing caps, each secured with four
bolts to the bedplate for exceptional bottom-end strength. The block integrates
structural oil passages for piston cooling jets, which spray oil onto the
underside of the pistons to manage thermal loads, a critical feature given the
engine’s high compression ratio.
Each cylinder head is a separate aluminum casting,
featuring a four-valve-per-cylinder arrangement. The DOHC valvetrain employs
roller-type cam followers to minimize friction between the camshaft lobes and
the valve stems. The intake valves are actuated by a continuously variable
timing system on both the intake and exhaust camshafts, allowing the engine to
optimize volumetric efficiency across a wide rpm range.
Valve diameters are optimized for the FSI combustion process: intake valves are
33.9 mm (1.33 in) in diameter, while exhaust valves are 28.5 mm (1.12 in). The
valves are constructed from high-temperature resistant steel, with sodium-filled
exhaust valves used to dissipate heat more effectively. The valve seats are a
copper-alloy material, designed to withstand the high thermal loads of the
direct injection combustion cycle.
The fuel system is a direct injection (FSI) setup
operating at high pressure. A single, engine-driven high-pressure fuel pump,
mounted on the right cylinder head and actuated by a dedicated camshaft lobe,
generates fuel pressures up to 150 bar (2175 psi) in the fuel rail. This
pressure is substantially higher than port-injection systems, enabling precise
fuel atomization directly into the combustion chamber.
Piezo-electric injectors are employed, which allow for multiple injection events
per combustion cycle, including a stratified charge mode under light load
conditions to improve fuel economy. The system requires premium unleaded
gasoline with a minimum octane rating of 95 RON for standard operation, though
98 RON is recommended for optimal performance and combustion stability.
The lubrication system utilizes a variable-displacement
oil pump, a design that adjusts oil flow based on engine speed and load to
reduce parasitic drag. The pump maintains a pressure-controlled circuit to
supply the crankshaft bearings, camshafts, and the piston cooling jets. Total
oil capacity, including the filter, is 7.7 liters (8.1 qt).
The oil specification strictly adheres to VW 502 00, which mandates a synthetic
formulation in viscosities such as SAE 5W-40, 5W-30, or 0W-40. An integrated oil
cooler, using engine coolant, maintains the oil at optimal operating
temperatures. The oil pan is a two-piece design comprising an aluminum upper
section and a steel lower sump.
The cooling system has a total capacity of 15.0 liters
(15.9 qt) and employs a cross-flow design with a thermostatically controlled
electric water pump. The system uses G12++ or G13 coolant, characterized by a
pink or purple color, which is a silicate-free, long-life formulation.
A dual-circuit cooling strategy is implemented: one circuit for the cylinder
heads to manage the high thermal stress of the combustion chambers, and another
for the cylinder block to maintain optimal cylinder wall temperature for
friction reduction. The main radiator is complemented by an auxiliary radiator
in the left front fender well to provide additional cooling capacity for the V8
configuration in the tight engine bay of the Audi A8.
| Intake and Exhaust Systems |
Intake System: A two-stage, variable-length intake
manifold is used. Acoustic actuators adjust the intake runner length via flaps,
optimizing airflow velocity at low rpm for torque and maximizing volume at high
rpm for peak power.
Exhaust System: Dual exhaust manifolds are constructed from stainless steel and
integrate a close-coupled catalytic converter on each bank to ensure rapid
light-off for emissions compliance. The system includes four lambda sensors (two
pre-catalyst and two post-catalyst) for precise closed-loop fuel control.
The engine employs a coil-on-plug ignition system with
individual pencil-style coils for each spark plug. This design eliminates
high-tension spark plug wires, ensuring consistent spark delivery and reduced
electromagnetic interference.
The engine’s physical dimensions are dictated by its
compact 90-deg V8 architecture. Overall length is 770 mm (30.3 in), width is 850
mm (33.5 in), and height is 720 mm (28.3 in). The engine’s dry weight, fully
dressed with all ancillary components including the intake manifold and
alternator but without fluids, is 220 kg (485 lb).
Engine Oil: Capacity with filter change is 7.7 liters
(8.1 qt). The oil change interval is specified as up to 15,000 km (9,300 mi) or
12 months under normal driving conditions, though a 10,000 km (6,200 mi)
interval is recommended for severe duty. Coolant: Total system capacity is 15.0
liters (15.9 qt). Coolant should be replaced every 5 years or 100,000 km (62,000
mi).
Spark Plugs: The recommended plug is a long-life platinum or iridium type with a
gap of 0.8 mm to 1.0 mm (0.031 in to 0.039 in). Replacement interval is 60,000
km (37,000 mi). Timing Chain: While the timing chains are designed for the
engine’s service life, inspection for elongation and tensioner wear is
recommended beyond 150,000 km (93,000 mi). Audible rattling on cold start from
the rear of the engine may indicate chain guide wear.
Carbon Cleaning: Due to the FSI direct injection design, intake valve deposits
can accumulate over time. A manual cleaning procedure, such as walnut blasting,
is the definitive remedy and is often recommended between 80,000 km and 100,000
km (50,000 mi and 62,000 mi) to restore performance and smooth idle. Air Filter:
The dry-panel air filter replacement interval is 60,000 km (37,000 mi), though
more frequent checks in dusty environments are advised.
Cylinder Head Bolts: Stage 1: 35 Nm (26 lb-ft).
Cylinder Head Bolts: Stage 2: 60 Nm (44 lb-ft).
Main Bearing Cap Bolts: 65 Nm (48 lb-ft) + 90° (1/4 turn).
Connecting Rod Cap Bolts: 30 Nm (22 lb-ft) + 90° (1/4 turn)
Camshaft Bearing Caps: 20 Nm (15 lb-ft).
Camshaft Adjuster Bolts: 80 Nm (59 lb-ft).
Flywheel / Drive Plate Bolts: 60 Nm (44 lb-ft) + 90° (1/4 turn).
Oil Drain Plug: 30 Nm (22 lb-ft).
Oil Filter Housing to Block: 25 Nm (18 lb-ft).
Spark Plugs: 25 Nm to 30 Nm (18 lb-ft to 22 lb-ft).
Intake Manifold to Cylinder Head: 20 Nm (15 lb-ft).
Exhaust Manifold to Cylinder Head: 25 Nm (18 lb-ft).
High-Pressure Fuel Pump Mounting: 20 Nm (15 lb-ft).
Coolant Temperature Sensor: 20 Nm (15 lb-ft).
Engine Mounts to Cylinder Block: 45 Nm (33 lb-ft) + 90° (1/4 turn).
The Audi CDRA engine was exclusively utilized in the
following model: Audi A8 (D4, Typ 4H): 2009 to 2012 model years. It was offered
as the 4.2 FSI variant, serving as the mid-range V8 option positioned between
the 3.0-liter V6 and the 6.3-liter W12.
In the A8, the engine was paired exclusively
with an 8-speed Tiptronic automatic transmission (ZF 8HP) and Audi’s
quattro permanent all-wheel-drive system.
____________________________________________________________________________________
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Industrial Engines Technical Specifications |
| Outboard Engines Technical Specifications |
