Audi S4 Engine for Sale | OEM Used Legendary 4.2 Liter V8 Producing 340 HP

Legendary 4.2 liter naturally-aspirated V8 for the B6 / B7 S4 V8 era. The Audi S4 4.2L V8 is the legendary naturally-aspirated V8 that powered the B6 S4 (2003-2005) and B7 S4 (2005-2008) generations. It represents the V8 S4 era before Audi moved to supercharged V6 (3.0T in B8 S4 2009-2016) and twin-turbo V6 (3.0 TFSI in B9 S4 2017 plus) for subsequent S4 generations. The 4.2L V8 (engine codes BBK for B6, BHF for B7 with revised internals) produces 340 HP at 7,000 RPM and 302 lb-ft of torque. Specifications: 4.2 liters displacement (4,163 cc), 90-degree V8 conventional architecture, two cylinder heads (one per bank), aluminum block and heads, DOHC with 5 valves per cylinder on BBK (40 valves total) or 4 valves per cylinder on BHF (32 valves total), variable valve timing, port fuel injection (NOT direct injection), naturally aspirated, timing chain driven, approximately 7,200 RPM redline. Universally praised by automotive journalists as one of the best-sounding production V8 engines.

Special period in Audi performance heritage between the B5 twin-turbo V6 and B8 supercharged V6 eras. The B6 / B7 S4 with the 4.2L V8 holds a special place in Audi performance heritage. S4 lineage: the S4 nameplate began with the C4 S4 (1992-1994) and continued through C5 / B5 / B6 / B7 / B8 / B9 generations, with each generation representing different engine architecture. V8 era: the B6 / B7 S4 (2003-2008) used the 4.2L V8; the predecessor B5 S4 (2000-2002) used a twin-turbo 2.7L V6; the successor B8 S4 (2009-2016) used a supercharged 3.0L V6; the current B9 S4 (2017 plus) uses a twin-turbo 3.0L V6. Universally praised: automotive journalists frequently cite the B6 / B7 S4 V8 as one of the best-sounding production V8 engines, with a high-revving naturally-aspirated character. RS4 B7 sibling: the RS4 B7 (2006-2008) used the same 4.2L V8 architecture but with revised internals producing 420 HP. Quattro all-wheel drive standard. Manual transmission 6-speed available alongside the Tiptronic automatic.

Engine code, valve count, and styling refinements. The B6 S4 and B7 S4 share the same general platform and the 4.2L V8 architecture, but have key differences. B6 S4 (2003-2005): engine code BBK, 5 valves per cylinder (40 valves total), 340 HP at 7,000 RPM. B7 S4 (2005-2008): engine code BHF, 4 valves per cylinder (32 valves total) with revised internals, 340 HP at 7,000 RPM (same output as B6, different valve count). B7 facelift: updated styling and minor mechanical refinements. B7 RS4 (2006-2008): 4.2L V8 with revised internals producing 420 HP, separate engine from the standard B7 S4 V8 (the RS4 variant is a higher-performance derivative of the same architecture). The BBK and BHF are NOT directly interchangeable across B6 / B7 chassis without ECU and wiring harness modification.

Seven well-documented failure modes. Timing chain tensioner failure: the 4.2L V8 has a documented timing chain issue, particularly on early B6 BBK applications; chain tensioner can fail causing chain slap, eventual chain skip, and potential engine damage. Carbon buildup on intake valves: while port fuel injection (not direct injection), carbon can still accumulate on intake valves from blow-by gases at high mileage. Oil consumption: some 4.2L V8 examples exhibit elevated oil consumption with age, similar to other VAG engines of the era. Coil pack failure: individual ignition coils can fail with age (8 coils total, one per cylinder), causing misfires that can damage catalytic converters if not addressed. Coolant leak from water pump or thermostat housing: the 4.2L V8 cooling system has known wear points. Cam adjuster (variable valve timing) failure: the cam adjuster solenoids can fail causing variable valve timing codes. Secondary air injection pump failure: California emissions equipment that can fail with age.

Four Audi engines in plus the Q7 water pump in. The Audi S4 4.2L V8 (this listing) is the legendary naturally-aspirated V8 from the B6 / B7 S4 V8 era. The Audi A4 2.0L EA888 TFSI is the modern 2.0L turbocharged direct-injection inline-4 (the modern smaller turbocharged inline-4 that succeeded the naturally-aspirated V6 / V8 era for standard Audi applications). The Audi RS3 2.5L TFSI is the legendary 5-cylinder TFSI turbocharged engine (the modern high-performance Audi turbocharged inline-5 with distinctive 5-cylinder sound). The Audi Q7 3.6L FSI V6 is the 3.6L FSI naturally-aspirated VR6 narrow-angle V6 in the Q7 4L 2007-2010 application (the related naturally-aspirated VR6 from the same Q7 4L era as the B7 S4). Four Audi engine listings across : EA888 2.0L TFSI inline-4 modern standard, 2.5L TFSI inline-5 modern high-performance, 3.6L FSI VR6 naturally-aspirated SUV era, (this listing) 4.2L V8 naturally-aspirated S4 era. Together they represent the evolution from naturally-aspirated V6 / V8 to modern turbocharged inline-4 / inline-5. Plus the Audi Q7 water pump.

Yes. The RS4 B7 used the same 4.2L V8 architecture with revised internals producing 420 HP. The RS4 B7 (2006-2008) used the same 4.2L V8 architecture as the standard B7 S4, but with revised internals to produce 420 HP (vs 340 HP in the standard S4). The RS4 B7 engine is a higher-performance derivative of the same V8 architecture, with: higher-flowing cylinder heads, revised intake manifold, sport-tuned camshafts, performance ECU calibration, and other refinements that increase output by approximately 80 HP. The RS4 engine code is BNS (not BBK or BHF). The RS4 B7 also used a manual transmission (6-speed) standard, with no automatic option, representing the most driver-focused RS-trim variant of the V8 S4 era. RS4 B7 engines are highly sought after by enthusiasts and command higher prices than standard S4 V8 engines. This listing is for the standard B6 BBK and B7 BHF S4 V8 engines (not the RS4 BNS V8); call (855) 634-4447 if you need an RS4 B7 BNS V8 specifically.

Timing chain tensioner inspection, coil packs, cam adjusters, oil consumption assessment. After acquiring a used Audi S4 4.2L V8 engine, budget for these preventive maintenance items. Timing chain tensioner inspection: budget $300-500 for inspection (replacement only if needed, typically $2,000-3,500 if chain tensioner has failed and chain has skipped). Coil pack replacement: budget $400-700 for a full set of 8 coil packs as preventive maintenance. Cam adjuster solenoid replacement: budget $300-500 for variable valve timing solenoids if codes are present. Oil consumption assessment: monitor oil level frequently during break-in period, since some 4.2L V8 examples exhibit elevated oil consumption. Carbon cleaning: budget $400-800 for intake valve cleaning if mileage is high (despite port injection, blow-by gases can cause carbon accumulation over time). Cooling system service: water pump and thermostat housing are known wear points; budget $400-600 for preventive replacement. Secondary air injection pump (California emissions vehicles): may need replacement on high-mileage examples.

No. There is no core return required.