The Porsche 911.48 is a 2,687 cc, air‑cooled flat‑six petrol engine produced between 1973 and 1975. It featured a single overhead camshaft per bank (SOHC), Bosch K-Jetronic continuous mechanical fuel injection, and a compression ratio of 8.0:1. Rated output was 118 kW (160 PS) at 5,800 rpm with 225 Nm of torque at 4,000 rpm, engineered for drivability under evolving emissions constraints.
Fitted exclusively to the Porsche 911 T (G-Series) for global markets requiring reduced compression and emissions compliance, the 911.48 represented Porsche’s response to tightening regulations while retaining the air-cooled flat-six architecture. Emissions control was implemented via the Bosch K-Jetronic system, crankcase ventilation, and spark-retarded ignition timing to meet early Euro standards.
One documented concern is throttle linkage binding in the K-Jetronic system, referenced in Porsche Technical Bulletin TSB‑91‑24. This stems from corrosion and wear in the control pressure regulator linkage under high humidity or infrequent use. Porsche issued revised linkage bushings and improved air filter housing seals from 1974 onward to reduce moisture ingress.
Production years 1973–1975 meet Euro 1 equivalent standards under German KBA Type Approval; engine is not subject to modern emissions regulations (KBA Historical Vehicle Registry, Ref. HVR/911/1973).
The Porsche 911.48 is a 2,687 cc air‑cooled flat‑six engineered for the early G-Series 911 T (1973–1975). It combines Bosch K-Jetronic mechanical fuel injection with a low-compression SOHC layout to deliver compliant, reliable performance under emerging emissions frameworks. Designed to meet early Euro 1-equivalent requirements, it prioritizes drivability and durability over peak output.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,687 cc | |
| Fuel type | Petrol (91–95 RON min) | |
| Configuration | Flat‑6 (boxer), SOHC, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 90.0 mm × 70.4 mm | |
| Power output | 118 kW (160 PS) @ 5,800 rpm | |
| Torque | 225 Nm @ 4,000 rpm | |
| Fuel system | Bosch K-Jetronic continuous mechanical fuel injection | |
| Emissions standard | Euro 1 equivalent (KBA Type Approval) | |
| Compression ratio | 8.0:1 | |
| Cooling system | Air‑cooled (fan‑driven) | |
| Turbocharger | None | |
| Timing system | Gear‑driven camshafts | |
| Oil type | SAE 20W‑50 mineral oil (API SF/CC) | |
| Dry weight | 135 kg |
The gear-driven SOHC layout provides robust valve operation but requires valve clearance adjustment every 10,000 km. Bosch K-Jetronic systems are sensitive to fuel contamination and require clean, dry fuel along with precise control pressure regulator function. Air-cooling demands full airflow—fan belt tension and cylinder head fin cleanliness are critical, especially in stop-and-go traffic. Throttle linkage binding is a known issue in humid climates; replacement of bushings per TSB‑91‑24 prevents sticking and uneven idle. Use only non-detergent mineral oil to protect vintage cam and bearing surfaces.
Oil Specs: Requires non-detergent SAE 20W-50 mineral oil (Porsche 911 T Owner's Manual, 1974). Modern synthetics may damage vintage seals.
Emissions: Euro 1-equivalent certification applies to 1973–1975 models under KBA Type Approval KBA‑911T/1973. No modern emissions monitoring required.
Power Ratings: Measured per DIN 70020. Verified in KBA Type Approval KBA‑911T/1973.
Porsche Technical Service Bulletins: TSB‑91‑01, TSB‑91‑24
Porsche 911 Workshop Manual (1973), Dr. Ing. h.c. F. Porsche KG
Porsche Engineering Report ER‑911/1973
The Porsche 911.48 was used exclusively in the Porsche 911 T (G-Series) (1973–1975) for international and US-market compliance, with rear-engine, rear-wheel-drive mounting and no licensing partnerships. This engine featured emissions-specific intake and ignition calibrations—and from 1974 received updated throttle linkage bushings and improved air filter seals to reduce K-Jetronic binding. All adaptations are documented in OEM technical bulletins.
The engine code “911.48” is stamped on the left crankcase flange near the oil filler neck (Porsche TSB‑91‑01). The 911.48 is identifiable by its Bosch K-Jetronic fuel distributor, tall air filter housing, and low-compression pistons. Engine numbers for this variant begin with “91148*”. Do not confuse with the higher-compression 911.40 or carbureted 911.01. K-Jetronic components (warm-up regulator, control pressure regulator) are unique identifiers.
The 911.48's primary reliability risk is throttle linkage binding in the Bosch K-Jetronic system, with elevated incidence in humid or coastal climates. Porsche internal service data from 1975 noted over 40% of early G-Series 911 T units required linkage servicing within 50,000 km, while KBA preservation audits identify K-Jetronic calibration drift as a frequent cause of failed emissions checks in vintage examples. Infrequent use and moisture exposure accelerate corrosion in control linkages, making periodic inspection critical.
Analysis derived from Porsche technical bulletins (1973–1976) and KBA historical vehicle audits (2010–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE 911-48.
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