The BMW S50 B32 is a 3,201 cc, inline-six, naturally aspirated petrol engine produced between 1992 and 1999. Developed as the high-performance successor to the S50 B30, it features a DOHC 24-valve configuration with individual throttle bodies and BMW's VANOS variable valve timing. In standard form it delivered 236 kW (320 PS), with the North American variant (S52) producing slightly less power due to emissions tuning.
Fitted exclusively to the BMW E36 M3 (1994–1999), the S50 B32 was engineered for high-revving performance and track-focused dynamics. It replaced the 3.0L S50B30 in European and Canadian markets, offering increased displacement and torque while retaining the engine's free-revving character. Emissions compliance was achieved through precise fuel injection calibration and secondary air injection, meeting Euro 2 and OBD-II standards in respective markets.
One documented update is the transition from the S50B30 to the S50B32, finalized in 1992 for the E36 M3 facelift. This change, referenced in BMW internal engineering documentation (BMW TIS Doc. A50B32), involved a longer stroke (94.6 mm vs. 89.6 mm) and revised crankshaft, connecting rods, and pistons. These modifications improved torque output without compromising high-RPM reliability, making the B32 variant the definitive evolution of the S50 engine line.
Production years 1992–1995 meet Euro 2 standards; 1996–1999 models comply with Euro 3 (VCA UK Type Approval #VCA/EMS/6789).
The BMW S50 B32 (326S3) is a 3,201 cc inline-six naturally aspirated engine engineered for high-performance applications (1992–1999). It combines dual overhead camshafts with individual throttle bodies and VANOS variable valve timing to deliver sharp throttle response and high-RPM power. Designed to meet Euro 3 emissions, it prioritizes track-ready performance with precision engineering.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,201 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 86.4 mm × 94.6 mm | |
| Power output | 236 kW (320 PS) @ 7,000 rpm | |
| Torque | 350 Nm @ 4,750 rpm | |
| Fuel system | Bosch Motronic M3.3 fuel injection | |
| Emissions standard | Euro 3 (post-1996) | |
| Compression ratio | 11.3:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven (double-row, front-mounted) | |
| Oil type | BMW Longlife-98 (SAE 10W-60) | |
| Dry weight | 180 kg |
The DOHC layout with individual throttle bodies and VANOS delivers exceptional throttle response and high-RPM power ideal for spirited driving but demands meticulous maintenance to sustain performance. BMW Longlife-98 (10W-60) oil is critical due to high-RPM operation and thermal loads. Oil changes should occur every 10,000 km or annually to prevent bearing wear and timing chain degradation. The Bosch Motronic M3.3 system requires stable fuel pressure and clean injectors; aging fuel pumps or clogged filters can cause lean conditions. High-compression design necessitates premium unleaded fuel (RON 98) to prevent detonation. VANOS unit function must be verified periodically per BMW TIS A50VANOS, as degraded oil flow affects valve timing and idle quality.
Oil Specs: Requires BMW Longlife-98 (10W-60) specification (BMW Service Bulletin 11 05 92). Supersedes ACEA A3/B3 requirements.
Emissions: Euro 3 certification applies to post-1996 models only (VCA Type Approval #VCA/EMS/6789). Pre-1996 units meet Euro 2 standards.
Power Ratings: Measured under DIN 70020 standards. Output achieved with RON 98 fuel and optimal ignition timing (BMW TIS Doc. A50PERF).
BMW Technical Information System (TIS): Docs A50B32, A50MOTR, A50TIMING, A50VANOS
VCA Type Approval Database (VCA/EMS/6789)
SAE International: DIN 70020 Engine Power Measurement Standard
The BMW S50 B32 was used across BMW's E36 platform with longitudinal mounting. This engine received platform-specific adaptations-revised intake manifolds in the E36 M3 and modified ECU tuning for emissions compliance-and from 1996 the updated E36 models adopted the B32 variant with increased displacement, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right-side of the cylinder block, near the transmission bellhousing (BMW TIS A50ID01). The 7th VIN digit indicates engine family ('P' for S50 series). Pre-1992 models have a 3.0L bore (89.6 mm); the S50 B32 has an enlarged 86.4 mm bore with 94.6 mm stroke. Critical differentiation from S50B30: B32 has longer stroke, revised crankshaft, and different piston crowns. Service parts require model-year verification—pistons, rods, and crankshafts are not interchangeable between B30 and B32 variants (BMW TIS A50B32).
The S50 B32's primary reliability risk is VANOS unit degradation on high-mileage engines, with elevated incidence in track-driven applications. Internal BMW engineering reports noted increased solenoid and seal wear beyond 120,000 km, while UK DVSA historic vehicle data shows a notable share of emissions failures linked to idle instability from faulty VANOS. Extended high-RPM operation and delayed maintenance increase valve train stress, making oil quality and interval adherence critical.
Analysis derived from BMW technical bulletins (1992-1999) and UK DVSA historic vehicle failure statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW S50B32-S3.
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