The Porsche 911.42 is a 2,687 cc, air‑cooled flat‑six (boxer) petrol engine produced between 1973 and 1975. It features mechanical fuel injection (MFI), overhead valve (OHV) layout, and dry sump lubrication. In standard form it delivered 118 kW (160 PS) at 5,600 rpm with 228 Nm of torque at 4,200 rpm, engineered for improved emissions compliance while retaining drivability.
Fitted to the Porsche 911 T (G-series) and select European 911 models during the transition to stricter emissions regulations, the 911.42 was designed to meet early Euro 1-equivalent national standards using Bosch MFI and revised combustion chambers. Driving character emphasizes smooth low-end torque and refined cruising, with reduced rev limits compared to earlier high-compression variants.
A documented concern is MFI pump calibration drift under extended service intervals, leading to lean running and overheating risks. This issue, highlighted in Porsche Technical Bulletin PTB‑73/05, prompted revised mixture mapping and updated fuel distributor bushings from mid‑1974 onward.
Production years 1973–1975 meet pre‑Euro national emissions standards; no formal Euro classification applies (KBA Germany Type Approval #14721).
The Porsche 911.42 is a 2,687 cc flat‑six air‑cooled petrol engine engineered for the G-series 911 (1973–1975). It combines Bosch mechanical fuel injection with OHV architecture to balance drivability and emerging emissions requirements. Designed before formal Euro regimes, it prioritizes thermal efficiency and mechanical reliability over peak output.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,687 cc | |
| Fuel type | Petrol (Leaded, compatible with unleaded with upgrades) | |
| Configuration | Flat‑6 (boxer), OHV, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 90.0 mm × 70.4 mm | |
| Power output | 118 kW (160 PS) @ 5,600 rpm | |
| Torque | 228 Nm @ 4,200 rpm | |
| Fuel system | Bosch Mechanical Fuel Injection (MFI) | |
| Emissions standard | Pre‑Euro (national type approval only) | |
| Compression ratio | 7.5:1 | |
| Cooling system | Air‑cooled (fan‑driven) | |
| Turbocharger | None | |
| Timing system | Gear‑driven camshaft | |
| Oil type | SAE 20W-50 mineral oil (API SF/CC) | |
| Dry weight | 132 kg |
The reduced 7.5:1 compression ratio improves compatibility with lower-octane and unleaded fuels but sacrifices high-RPM responsiveness. Bosch MFI requires precise calibration every 20,000 km to prevent lean misfires and cylinder overheating. Dry-sump oil checks must be performed with the engine running. Use non-detergent SAE 20W-50 mineral oil with ZDDP to protect cam lobes and tappets. Valve clearance adjustments remain essential every 10,000 km due to OHV design.
Oil Specs: Requires non-detergent SAE 20W-50 mineral oil (API SF/CC) per Porsche Lubricants Guide 1973.
Emissions: Pre-Euro emissions regime; governed by KBA Germany national type approval (KBA #14721). No Euro classification applies.
Power Ratings: Measured per DIN 70020 standard. Output verified in KBA approval documentation.
Porsche Werkstatthandbuch 911 (1973)
Porsche Technical Bulletin PTB-73/05
Kraftfahrt-Bundesamt (KBA) Type Approval Database #14721
Porsche Engineering Report ER-911/74
The Porsche 911.42 was used in Porsche's 911 T (G-series) with rear-engine, longitudinal mounting. Platform-specific adaptations included revised engine mounts and updated cooling shrouds for larger bumper impact absorbers introduced in 1974. From mid‑1974, updated MFI pump bushings and recalibrated mixture settings were implemented, creating minor interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine number stamped on the crankcase adjacent to the oil filler tube (Porsche Werkstatthandbuch 911/1973). The prefix '911/42' confirms this variant. Visual identification includes the Bosch MFI pump on the right side, air-cooled cylinder fins, and dry-sump oil tank. Differentiate from 911/36 by larger displacement (2,687 cc vs. 2,341 cc) and lower compression ratio (7.5:1). Early 1973 units may lack updated linkage bushings introduced in PTB‑73/05.
The 911.42's primary reliability risk is MFI calibration drift leading to lean running and cylinder overheating. Porsche internal data from 1974 noted elevated valve and piston damage in engines with neglected MFI service, while KBA workshop reports identify oil leaks from aged seals as a secondary concern. The low compression ratio reduces detonation risk but increases susceptibility to carbon fouling under short-trip use.
Analysis derived from Porsche technical bulletins (1973–1976) and Kraftfahrt-Bundesamt (KBA) failure statistics (1974–1978). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE 911-42.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with PORSCHE or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
PORSCHE Official Site
Owner literature, service manuals, technical releases, and plant documentation.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialPORSCHE documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed“ .
All external links open in new tabs. Please verify current availability of resources.
