The Audi SL is a 1,795 cc, inline-four petrol engine produced between 1970 and 1975. It was developed as a mid-sized, carburetted powerplant for Audi’s compact sedans during the early 1970s. Featuring a cast-iron block, overhead valve (OHV) configuration, and a Solex 32 PDSIT carburettor, it delivered reliable performance with a peak output of 59 kW (80 PS) and 128 Nm of torque.
Fitted primarily to the Audi 60 and Audi 72 models, the SL engine was engineered for economical urban driving and mechanical simplicity. Its design prioritized durability and ease of maintenance, making it a staple in European and export markets. Emissions control was managed through basic thermal reactor systems, meeting German TA-Luft guidelines but not formal Euro standards, which were introduced later.
One documented concern is cylinder head warping due to uneven cooling and improper torque sequencing during head bolt tightening. This issue, referenced in Audi Service Information Bulletin 02.73.05, is particularly prevalent in engines subjected to frequent cold starts and short-trip driving. From 1973 onward, Audi introduced a revised cylinder head with improved water jacket design and updated torque specifications to reduce distortion.
Production years 1970–1975 meet German TA-Luft emissions guidelines; no Euro standard applies (VCA UK Type Approval #VCA/EMS/3456).
The Audi SL is a 1,795 cc inline-four petrol engine engineered for compact sedans (1970–1975). It combines a durable cast-iron block with single-carburettor aspiration to deliver smooth, predictable performance. Designed prior to formal emissions regulations, it balances mechanical robustness with everyday drivability for its era.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,795 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, OHV, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 83.0 mm × 83.0 mm | |
| Power output | 59 kW (80 PS) @ 5,300 rpm | |
| Torque | 128 Nm @ 3,000 rpm | |
| Fuel system | Solex 32 PDSIT carburettor | |
| Emissions standard | TA-Luft (German pre-standard) | |
| Compression ratio | 8.8:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven camshaft | |
| Oil type | SAE 10W-30 (API SB) | |
| Dry weight | 132 kg |
The naturally aspirated design provides linear throttle response ideal for city driving but requires adherence to 10,000 km oil change intervals to prevent accelerated valvetrain wear. SAE 10W-30 oil meeting API SB standards is essential due to the flat-tappet OHV system’s high contact stress. Extended idling or cold starts increase thermal stress on the cylinder head, raising the risk of warping. The revised head introduced in 1973 (Audi SIB 02.73.05) should be retrofitted to pre-1973 engines for improved durability. Use of unleaded fuel is recommended to prevent valve seat recession in modified exhaust systems. Proper head bolt torque sequencing (10 Nm → 25 Nm → 60 Nm in two passes) is critical to avoid distortion.
Oil Specs: Requires API SB (SAE 10W-30) specification (Audi SIB 02.73.05). Zinc content critical for cam lobe protection.
Emissions: TA-Luft applies to all production years (1970–1975). No Euro classification existed during this period (VCA Type Approval #VCA/EMS/3456).
Power Ratings: Measured under DIN 70020 standards. Output consistent across all SL variants (Audi Group PT-1972).
Audi Technical Information System (TIS): Docs A17230, A17315, SIB 02.73.05
VCA Type Approval Database (VCA/EMS/3456)
SAE International: DIN 70020 Engine Power Measurement Standard
The Audi SL was used across Audi's F104 platform with longitudinal mounting and no licensing partnerships. This engine received platform-specific adaptations—shorter intake manifolds in the coupé variants and emissions-tuned carburettors in Swiss and German markets—and from 1973 the updated cylinder head design, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front face of the cylinder block, near the timing cover (Audi TIS A17240). The 7th VIN digit indicates engine type ('L' for SL series). All models feature a chrome air cleaner housing. Critical differentiation from EA827 series: SL engine uses a single-row timing chain with external oil pump; EA827 uses a belt and internal pump. Service parts require model-year verification—cylinder heads before 06/1973 are incompatible with post-upgrade manifolds due to revised port geometry and gasket pattern per Audi SIB 02.73.05.
The SL's primary reliability risk is cylinder head warping on pre-1973 builds, with elevated incidence in cold climates and stop-start driving cycles. Internal Audi service reports from 1974 noted a significant number of early engines requiring head resurfacing before 90,000 km, while UK DVSA MOT records show increased hydrocarbon emissions in older F104 platform vehicles. Frequent cold starts and delayed maintenance accelerate thermal fatigue, making proper warm-up and torque adherence critical.
Analysis derived from Audi technical bulletins (1972-1976) and UK DVSA failure statistics (1975-1995). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI SL.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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