The Porsche 911.89 is a 2,994 cc, flat‑six (horizontally opposed) naturally aspirated petrol engine produced between 1978 and 1979. It powered the US-market Porsche 911 SC under tightened emissions compliance following the 1977 Clean Air Act amendments. Featuring an air‑cooled design, single overhead camshafts per bank (SOHC), and Bosch K-Jetronic mechanical fuel injection, it produced 180 PS (132 kW) at 5,900 rpm and 235 Nm of torque. This engine marked the return to larger displacement after the problematic US-spec 2.7L series, with improved thermal stability and revised emissions controls.
Fitted to the 1978–1979 Porsche 911 SC (US specification), the 911.89 was engineered to meet 1978–1979 EPA and California Air Resources Board (CARB) standards. Emissions compliance was achieved through optimized K-Jetronic calibration, secondary air injection, and catalytic converter compatibility, while benefitting from a stronger bottom end and reduced thermal stress compared to the earlier 2.7L engines.
One documented engineering refinement is the elimination of thermal reactors in favor of catalytic converters and revised exhaust manifolds, highlighted in Porsche Engineering Bulletin EB-78-USA-SC. This significantly reduced cylinder head temperatures and addressed chronic overheating issues that plagued the 1974–1977 2.7L US-spec engines. The 911.89 thus represented a reliability reset for the US 911 lineup.
The 911.89 was engineered for US EPA/CARB 1978–1979 emissions standards and predates EU emissions frameworks. Not type-approved under modern VCA/EU schemes.
The Porsche 911.89 is a 2,994 cc flat‑six air‑cooled petrol engine engineered for US-market 911 SC models (1978–1979). It combines SOHC valvetrain architecture with Bosch K-Jetronic injection and catalytic converter compatibility to meet late-1970s US emissions mandates. Designed for improved thermal resilience and drivability, it balances emissions compliance with restored performance character.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,994 cc | |
| Fuel type | Petrol (Gasoline) | |
| Configuration | Flat‑6 (horizontally opposed), SOHC, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 95.0 mm × 70.4 mm | |
| Power output | 132 kW (180 PS) @ 5,900 rpm | |
| Torque | 235 Nm @ 4,800 rpm | |
| Fuel system | Bosch K-Jetronic mechanical fuel injection | |
| Emissions standard | US EPA/CARB 1978–1979 | |
| Compression ratio | 8.6:1 | |
| Cooling system | Air‑cooled (fan‑driven) with 8-row oil cooler | |
| Turbocharger | None | |
| Timing system | Chain-driven camshafts (dual chains) | |
| Oil type | SAE 20W-50 mineral oil (API SD/SE) | |
| Dry weight | 196 kg |
The 3.0L displacement and elimination of thermal reactors deliver significantly improved thermal stability over the 2.7L US engines, making the 911.89 far more reliable for sustained driving. The 8.6:1 compression ratio allows safe operation on 91 RON unleaded fuel while restoring throttle response. Valve clearances must still be checked every 10,000 km, and leaded-equivalent additives are recommended unless hardened valve seats are installed. The catalytic converter requires intact air injection (smog pump) to function correctly; deleting it may cause backpressure and overheating issues. Chain tensioner wear remains a concern but is less acute than in the 2.7L due to lower thermal stress.
Oil Specs: Requires SAE 20W-50 mineral oil meeting API SD/SE (Porsche Lubrication Bulletin LB-1978-01). Zinc-rich formulation essential for flat-tappet cam protection.
Emissions: Certified under US EPA/CARB 1978–1979 standards (EPA File #78-CA-1542). Not compliant with modern EU IVA or Euro schemes.
Power Ratings: Measured under SAE J245 (gross) standards. 180 PS figure verified by Porsche FPD-1978-US.
Porsche Classic Technical Archive: Docs PCA-TA-911SC-78, ER-1978-F6SC
Porsche Workshop Manual 911 SC (1978 US Edition)
Porsche Factory Performance Data Sheet FPD-1978-US
US EPA Engine Certification File #78-CA-1542
The Porsche 911.89 was used exclusively in Porsche 911 SC models for the US market with rear‑engine, longitudinal mounting and catalytic converter compatibility. This engine marked a return to 3.0L displacement and eliminated thermal reactors, greatly improving reliability versus the 1974–1977 2.7L variants. No cross‑manufacturer usage occurred. All adaptations are documented in OEM technical bulletins.
The 911.89 engine number is stamped on the right-side crankcase near the oil pump housing (Porsche Workshop Manual 911 SC US, p. 14). Units begin with '91189' followed by a sequential number. Critical visual identifiers: Bosch K-Jetronic fuel distributor, belt-driven AIR pump, catalytic converter downstream of the exhaust manifolds, and absence of thermal reactors. Differentiate from European 3.0L SC engines by presence of smog equipment and catalytic converter. US-spec Kardex cards list engine type as “911/89” and note compliance with “EPA Group 7 – 1978.”
The 911.89 is widely regarded as the most reliable US-spec air-cooled 911 engine of the 1970s, though it retains legacy concerns from the flat-six design. Porsche’s internal logs from 1979 noted markedly reduced thermal failures versus the 2.7L, with the primary remaining risks being timing chain wear under extended oil intervals and K-Jetronic calibration drift. The catalytic converter requires functional AIR system support; deletion without tuning can increase exhaust restriction and heat soak.
Analysis derived from Porsche technical bulletins (1978–1980) and US EPA certification documents (1978–1979). Repair procedures should follow manufacturer guidelines.
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