Audi CTUC Specifications
| Engine Model: Audi CTUC |
| Engine Type: 4-cycle 6-cylinder DOHC 24-valve supercharged liquid-cooled gasoline |
| Total Displacement: 183 cu.in (2.99 L) |
| Rated Engine Power: 268 Hp (200 kW) at 6000 rpm |
| Fuel System Type: Direct fuel injection |
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The Audi CTUC is a 3.0-liter, six-cylinder petrol
engine belonging to the EA837 Generation 2 family. It represents a high-output
variant within this engine series, distinguished by its use of a Roots-type
supercharger rather than a turbocharger, despite carrying the "TFSI" (Turbo Fuel
Stratified Injection) nomenclature.
Mechanically identical to the CTUB code, the CTUC was primarily deployed in the
Audi Q5 (8R) and the SQ5 models produced between 2012 and 2017. This engine is a
90-deg V6 configuration, utilizing direct fuel injection and a dual overhead
camshaft setup. Its design focuses on a compact layout, with the supercharger
nestled in the engine’s "V" and the timing drive mechanism located at the rear,
against the transmission bell housing.
Engine Code: CTUC.
Displacement: 2995 cc (183.0 cu.in).
Configuration: 90° V6.
Valvetrain: DOHC (Dual Overhead Camshafts), 4 valves per cylinder, 24 valves
total.
Bore x Stroke: 84.5 mm x 89.0 mm (3.33 in x 3.50 in).
Compression Ratio: 10.3:1.
Induction System: Eaton TVS (Twin Vortices Series) Roots-type supercharger,
intercooled.
Fuel System: FSI (Fuel Stratified Injection) - direct injection.
Camshaft Drive: Timing chain with a rear-mounted primary drive and secondary
chains for each cylinder head.
Max Power Output: 200 kW (272 PS / 268 hp) at 4,780-6,500 rpm.
Max Torque: 400 Nm (295 lb-ft) at 2,150-4,780 rpm.
Emission Standard: Euro 5 / Euro 6 (depending on model year and market).
Fuel Requirement: Premium unleaded, 95 RON minimum (98 RON recommended for
optimal performance).
Engine Oil Capacity (with filter): 6.8 L (7.2 qt).
Oil Specification: VW 502 00 (fixed service intervals) or VW 504 00 (extended
service intervals); 5W-30 or 5W-40 synthetic.
Cooling System Capacity: 11.0 L (11.6 qt) with G13 coolant.
Spark Plugs: NGK PFR8S8EG or equivalent.
Spark Plug Gap: 0.7-0.8 mm (0.028-0.031 in).
Firing Order: 1-4-3-6-2-5.
The cylinder block for the CTUC is constructed from
cast aluminum alloy (Gk-AlSi17Cu4Mg), which contributes to a significant
reduction in overall engine weight. This open-deck design integrates cast-iron
cylinder liners for durability and wear resistance. The block features a 90-deg
bank angle, optimizing the engine’s center of gravity and allowing for a compact
installation within the engine bay.
The main bearing caps are a fracture-split (cracked) design, constructed from
high-strength sintered metal, ensuring precise alignment and robust support for
the forged steel crankshaft. The block also incorporates the integrated oil
passages for piston cooling jets, which are crucial for thermal management under
high load.
Each cylinder head is a cast aluminum component
featuring a DOHC configuration with four valves per cylinder. The valve train
utilizes roller finger followers with hydraulic lash adjusters, which eliminate
the need for manual valve clearance adjustments and reduce valvetrain friction.
The intake and exhaust valves are arranged in a pent-roof combustion chamber
design.
The intake valves have a diameter of 34.0 mm (1.34 in), while the exhaust valves
measure 28.0 mm (1.10 in). The valves are actuated by hollow camshafts that are
lightweight and provide precise control. The exhaust camshaft is equipped with a
variable valve timing (VVT) adjustment range, managed by a vane-type adjuster
located at the rear of the engine. The cylinder heads also house the direct fuel
injectors positioned centrally between the valves.
The CTUC employs a high-pressure direct fuel injection
system, branded as FSI. The system operates with a fuel pressure that varies
between 50 bar (725 psi) at idle to 150 bar (2175 psi) under high-load
conditions.
A high-pressure fuel pump, driven by a cam lobe on the vacuum pump at the rear
of the right cylinder head, pressurizes the fuel rail. Each cylinder is served
by a solenoid-actuated injector that delivers fuel directly into the combustion
chamber. The supercharger, integrated with a water-cooled charge air cooler,
compresses the intake air before it enters the cylinders, allowing for a high
compression ratio (10.3:1) and efficient combustion across the rev range.
The lubrication system is a dry-sump style system,
though it operates on a wet-sump principle with an integrated oil module. The
system capacity is 6.8 L. A variable-displacement vane-type oil pump, driven by
a chain from the crankshaft, adjusts oil pressure based on engine demand to
reduce parasitic losses. Oil pressure is regulated by the engine control unit
(ECU) and can vary between 1.8 bar (26 psi) at idle to over 4.5 bar (65 psi) at
high rpm.
The oil cooler and oil filter are integrated into a single modular unit mounted
to the side of the cylinder block for ease of service. Piston cooling nozzles
are integrated into the block and direct a continuous stream of oil to the
underside of the pistons to manage thermal stress during supercharged operation.
The cooling system is a dual-circuit arrangement with a
total capacity of 11.0 L. A primary circuit manages engine block and cylinder
head temperatures, while a secondary low-temperature circuit is dedicated to the
intercoolers integrated within the supercharger housing. The system uses a
cross-flow aluminum radiator and an electric coolant pump for the supercharger
circuit, which can operate independently after engine shutdown to prevent heat
soak.
A main mechanical coolant pump, driven by the supercharger’s drive belt,
circulates coolant through the engine. A map-controlled thermostat, integrated
into the coolant pump housing, allows the ECU to regulate the engine operating
temperature between 85°C and 105°C (185°F-221°F) to optimize efficiency and
thermal management.
Supercharger: The Eaton TVS Roots-type supercharger is
mounted in the “V” of the engine. It is driven by a poly-V belt via a magnetic
clutch that can decouple the supercharger under light loads to improve fuel
economy. Maximum boost pressure is approximately 0.8 bar (11.6 psi).
Engine Management: The engine is controlled by a Bosch MED 17.1.1 ECU. It
manages ignition timing, fuel injection, supercharger bypass valve operation,
variable valve timing, and the electronic throttle.
Ignition System: The system uses a coil-on-plug (COP) design, with individual
ignition coils mounted directly over each spark plug.
PCV (Positive Crankcase Ventilation): An integrated pressure-regulating valve is
housed within the top of the cylinder block, separating oil mist from blow-by
gases and routing them back into the intake system.
Vacuum System: A mechanical vacuum pump, mounted at the rear of the right
cylinder head, provides vacuum for the brake booster.
Overall Length (including ancillaries): 560 mm (22.0
in)
Overall Width: 710 mm (28.0 in)
Overall Height: 630 mm (24.8 in)
Dry Engine Weight (complete, without fluids): 190 kg (419 lb)
Engine Oil Change: 6.8 L with filter; interval varies
based on oil specification (fixed at 15,000 km / 10,000 mi with VW 502 00,
flexible up to 30,000 km / 20,000 mi with VW 504 00). Coolant Change: 11.0 L;
G13 coolant change interval is every 5 years or at specified mileage.
Spark Plug Replacement: 60,000 km (40,000 mi). Air Filter: Replace at 60,000 km
(40,000 mi) or more frequently in dusty conditions. Supercharger Drive Belt:
Inspect every 90,000 km (60,000 mi); replacement interval is variable.
Cylinder Head Bolts (M10 x 115): Stage 1: 40 Nm (30
lb-ft); Stage 2: 90 degs
Connecting Rod Bolts (M8 x 1.0): Stage 1: 50 Nm (37 lb-ft); Stage 2: 90 degs
Main Bearing Bolts (M10): Stage 1: 65 Nm (48 lb-ft); Stage 2: 90 degs
Supercharger Mounting Bolts (M6): 20 Nm (15 lb-ft)
Camshaft Bearing Caps: 10 Nm (7 lb-ft) + 90° (90 degs)
Timing Chain Tensioner (Central Bolt): 65 Nm (48 lb-ft)
Engine Oil Drain Plug (M14 x 1.5): 30 Nm (22 lb-ft)
Spark Plugs: 25 Nm (18 lb-ft)
Engine Mount Bracket to Block (M10): 40 Nm (30 lb-ft) + 90 degs
Vibration Damper (Crankshaft Pulley Bolt): 150 Nm (111 lb-ft) + 180 degs
The CTUC engine served as
the standard high-output V6 powerplant for the following models:
Audi Q5 (8R): 2012-2017. This includes the 3.0 TFSI quattro variant, where the
engine provided a balance of performance and efficiency in the mid-size SUV
segment.
Audi SQ5 (8R): 2013-2017. In certain markets,
particularly outside of North America, the CTUC was used in the
first-generation SQ5 before the introduction of the diesel variant. It
delivered 200 kW (272 PS) and 400 Nm, offering performance-oriented
characteristics in the compact performance SUV category.
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