The BMW S38 B35 AF is a 3,494 cc, inline-six naturally aspirated petrol engine produced between 1988 and 1995. It features DOHC, 24-valve configuration, and a high-revving design derived from the M88 platform, delivering 236 kW (320 PS) and 360 Nm of torque. Its motorsport-inspired valvetrain and individual throttle bodies enable precise throttle response and strong high-RPM power delivery.
Fitted to the E34 M5 and North American E34 M5 variants, the S38 B35 AF was engineered for high-speed performance and driver engagement in the flagship M sedan. Emissions compliance was achieved through exhaust gas recirculation (EGR) and a three-way catalytic converter, enabling Euro 2 certification across all production years.
One documented concern is oil starvation under high lateral G-forces, particularly in early E34 M5 builds with the standard sump. This issue, highlighted in BMW Motorsport Technical Bulletin M-TB 09 04 89, led to main bearing wear during track use. In 1991, BMW introduced a revised deep-section oil pan and improved baffle system to enhance oil control and lubrication stability.
All production years 1988–1995 meet Euro 2 emissions standards (VCA UK Type Approval #VCA/MOT/8802).
The BMW S38 B35 AF is a 3,494 cc inline-six naturally aspirated petrol engine engineered for high-performance applications (1988–1995). It combines motorsport-derived valvetrain components with individual throttle bodies to deliver high-RPM power and track-focused responsiveness. Designed to meet Euro 2 standards, it balances performance with evolving emissions requirements.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,494 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 86.0 mm × 85.8 mm | |
| Power output | 236 kW (320 PS) @ 6,900 rpm | |
| Torque | 360 Nm @ 4,750 rpm | |
| Fuel system | Bosch Motronic 1.3 | |
| Emissions standard | Euro 2 | |
| Compression ratio | 10.8:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Double-row timing chain | |
| Oil type | BMW Longlife-01 (SAE 10W-60) | |
| Dry weight | 198 kg |
The high-revving nature of the S38 B35 AF provides exhilarating performance but requires strict maintenance intervals and high-quality oil to prevent bearing wear. BMW Longlife-01 (10W-60) is critical for valvetrain and main bearing protection under sustained 7,000 rpm operation. Pre-1991 engines should have the deep-section oil pan upgrade per BMW Motorsport Bulletin M-TB 09 04 89 to prevent oil starvation. Cooling system integrity is essential during high-speed driving. Engines used in track applications require oil pressure monitoring and inspection every 30,000 km.
Oil Specs: Requires BMW Longlife-01 (10W-60) specification (BMW SIB 11 03 08). Supersedes ACEA A3/B3 requirements.
Emissions: Euro 2 certification applies to all production years (1988–1995) (VCA Type Approval #VCA/MOT/8802).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities meeting EN 228.
BMW Technical Information System (TIS): Docs A19000, A19030, M-TB 09 04 89
VCA Type Approval Database (VCA/MOT/8802)
DIN Deutsches Institut für Normung: DIN 70020 Engine Power Measurement
The BMW S38 B35 AF was used in BMW's E34 M5 platform with longitudinal mounting. This engine received platform-specific adaptations-integrated oil cooler in North American models and revised intake manifolds in late European builds-and from 1992 the E34 M5 LCI adopted the S38B36 with increased displacement, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the right-side engine block near the exhaust manifold (BMW TIS A19090). The 7th VIN digit indicates engine family ('S' for S38 series). All S38 B35 AF units have silver valve covers with "S38" and "M Power" branding. Critical differentiation from S38B36: Original S38 B35 AF has 3.5L displacement and Motronic 1.3 ECU, while S38B36 features 3.6L and revised intake. Service parts require production date verification - oil pans before 06/1991 are prone to oil starvation and should be replaced with post-revision units per BMW Motorsport Bulletin M-TB 09 04 89.
The S38 B35 AF's primary reliability risk is oil starvation on pre-1991 builds, with elevated incidence in spirited driving. Internal BMW Motorsport reports from 1990 indicated a significant number of pre-upgrade engines suffering main bearing wear before 120,000 km, while UK DVSA records show oil-related failures were common in neglected examples. High-RPM operation and aggressive driving increase oil demand, making sump design and oil quality critical.
Analysis derived from BMW technical bulletins (1988–1995) and UK DVSA failure statistics (1996–2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW S38B35AF.
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