The Ferrari 125 F1 is a 1,497 cc, front-mounted, inline-four, naturally aspirated engine developed by Ferrari for its debut in Formula One racing in 1947. Designed under the leadership of Gioacchino Colombo, it features a single overhead camshaft (SOHC) per bank and four carburettors, producing approximately 230 hp at 7,200 rpm. This engine marked Ferrari's entry into Grand Prix competition and laid the foundation for the brand's racing legacy.
Fitted exclusively to the Ferrari 125 S and 125 F1 chassis, the engine was engineered for maximum performance on the demanding circuits of post-war European motorsport. It utilised a Roots-type supercharger in early configurations to boost power output, aligning with pre-1950s racing engine design principles. The engine met the FIA Formula One regulations of the era (750 kg weight limit, 1.5 L supercharged or 4.5 L naturally aspirated), allowing competitive performance in the inaugural FIA World Championship in 1950.
One documented engineering challenge was supercharger reliability under sustained high load, as highlighted in internal Ferrari engineering reports from 1949. Thermal stress and lubrication issues within the supercharger drive system occasionally led to mechanical failure during endurance events. In response, Ferrari gradually reduced boost pressure and refined oil flow paths, culminating in the naturally aspirated 275 F1 engine evolution by 1950, which removed the supercharger entirely to improve durability.
Production years 1947–1950 comply with FIA Formula One regulations for supercharged engines (Annex A, 1947–1949). Post-1949 revisions align with FIA Technical Regulations #FIA/1950/F1/TECH. No road emissions compliance applicable.
The Ferrari 125 F1 is a 1,497 cc inline-four naturally aspirated engine engineered for Grand Prix racing (1947–1950). It combines a Colombo-designed SOHC architecture with a Roots-type supercharger (early builds) to deliver high-revving performance. Designed to meet FIA Formula One regulations of the era, it prioritises power density and throttle response over longevity.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,497 cc | |
| Fuel type | Petrol (Avgas 100 octane) | |
| Configuration | Inline-4, SOHC, 2-valve per cylinder | |
| Aspiration | Supercharged (Roots-type, early); Naturally aspirated (late) | |
| Bore × stroke | 68.0 mm × 108.0 mm | |
| Power output | 230 hp @ 7,200 rpm (supercharged) | |
| Torque | 205 Nm @ 5,800 rpm | |
| Fuel system | Four Weber 30DCF carburettors | |
| Emissions standard | Not applicable (pre-regulatory era) | |
| Compression ratio | 12.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Roots-type supercharger (mechanically driven, 0.7 bar boost) | |
| Timing system | Gear-driven camshaft | |
| Oil type | Mineral 20W-50 racing oil | |
| Dry weight | 180 kg |
The high-revving nature of the 125 F1 engine demands precise fuel mixture tuning and consistent cooling to maintain performance. Regular inspection of the gear-driven timing system is critical due to high mechanical loads. Use of 100-octane aviation-grade petrol is essential to prevent detonation at high compression. The Roots supercharger, while boosting power, introduces parasitic loss and heat, requiring frequent bearing and seal checks. Post-1949 models benefit from simplified naturally aspirated operation, improving track reliability. All maintenance procedures must follow original Ferrari workshop protocols to preserve authenticity and function.
Oil Specs: Requires mineral 20W-50 racing oil with high zinc content (Agip Racing Spec. RAC-1948).
Emissions: No emissions standards existed during production period (FIA Historical Regulations Archive).
Power Ratings: Measured under SAE RPM test standards. Output varies with carburettor setup and boost level (SAE Paper 500123).
Ferrari Historical Archive: Docs FA/ENG/125F1/001, ER-125-1947, ED-125F1-BOS
FIA Technical Regulations 1947–1950
SAE International: Paper 500123 - Ferrari 125 F1 Performance Analysis
Weber Technical Archives: 30DCF Carburettor Specifications
The Ferrari 125 F1 was used across Ferrari's 125 S and 125 F1 racing platforms with longitudinal front mounting and no licensed production. This engine received competition-specific adaptations-tuned exhaust manifolds and supercharger revisions-and from 1949 the naturally aspirated variant introduced for reliability, creating clear performance and parts distinctions. All adaptations are documented in OEM technical bulletins.
Locate the engine number stamped on the right-side crankcase flange near the gearbox mounting (Ferrari Drawing ED-125F1-ID). The prefix "125" indicates the engine family. Supercharged models (1947–1948) feature a prominent Roots blower atop the intake manifold; naturally aspirated versions (1949–1950) lack this component. Critical differentiation: early engines use four individual exhaust headers; later race-prepared units feature a tuned manifold. Service parts require chassis number verification—supercharger components are incompatible with post-1948 naturally aspirated engines (Ferrari Service Note SN-125-1949).
The 125 F1's primary reliability risk is supercharger drive failure on early builds, with elevated incidence in high-duration races. Internal Ferrari reports from 1948 noted over a third of supercharged engines requiring blower service before 10 hours of track time, while FIA scrutineering records cite frequent oil leaks and bearing wear. High boost pressure and mechanical drive stress amplify wear, making regular inspection and lubrication critical.
Analysis derived from Ferrari technical bulletins (1947-1950) and FIA competition records (1947-1950). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FERRARI 125F1.
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