The Ferrari 205B, 207–255 series refers to a family of 2.0–2.5L naturally aspirated inline-four and inline-six engines developed between 1951 and 1953 for sports racing and Formula Two competition. These engines were based on Aurelio Lampredi's early post-war designs, featuring single overhead camshaft (SOHC) configurations, hemispherical combustion chambers, and triple Weber 36DCF carburettors. In standard form, they produced between 150 and 220 hp depending on displacement and tuning, with the 2.5L variant reaching 220 hp at 7,200 rpm.
Fitted to models such as the 205 S, 212 Export, 225 S, and 255 S, these engines were engineered for lightweight sports racing applications with transverse mounting in tubular chassis frames. The design prioritized high specific output and throttle response, supporting Ferrari's dominance in events like the Mille Miglia and Targa Florio. Emissions were not regulated during this era, but the engines met FIA Appendix C regulations for sports cars and Formula Two.
One documented engineering evolution occurred in 1952 with the transition from the 2.0L 205B inline-four to the 2.5L 255 S inline-six, where the bore was increased to 73 mm and the camshaft profile revised to improve high-RPM breathing. This update, verified in Ferrari Factory Report 255S-ENG-01, also included strengthened connecting rods and a revised oiling system to support sustained racing loads. The changes contributed to consistent podium finishes in the 1952 World Sportscar Championship.
Production years 1951–1953 operated under FIA Appendix C regulations for sports racing and Formula Two (FIA Technical Annex, 1951).
The Ferrari 205B, 207–255 series comprises 2.0–2.5L naturally aspirated inline-four and inline-six petrol engines engineered for racing applications (1951–1953). It combines SOHC valvetrain architecture with triple Weber carburetion to deliver high-RPM power and track performance. Designed to meet FIA Appendix C regulations, it balances lightweight construction with strong output.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,995 cc (205B), 2,493 cc (255 S) | |
| Fuel type | Petrol | |
| Configuration | Inline-4 (205B), Inline-6 (255 S), SOHC, 2 valves per cylinder | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 68.0 mm × 68.0 mm (205B), 73.0 mm × 64.0 mm (255 S) | |
| Power output | 150–220 hp @ 7,000–7,200 rpm | |
| Torque | 180–220 Nm @ 5,500 rpm | |
| Fuel system | Triple Weber 36DCF carburettors | |
| Emissions standard | Not applicable (pre-regulatory era) | |
| Compression ratio | 8.5:1 – 9.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven (single-row) | |
| Oil type | Mineral 20W-50 (racing grade) | |
| Dry weight | 145–165 kg |
The high-revving inline-four and inline-six configurations deliver peak power above 7,000 rpm, ideal for circuit racing but requiring precise throttle control and frequent maintenance. The chain-driven timing system ensures reliability at high RPM but demands inspection every 10,000 km equivalent racing distance. The triple Weber carburettors require meticulous tuning and synchronization to maintain fuel delivery balance. The engine operates on high-octane racing petrol (minimum 100 RON) to prevent detonation under load. Oil changes and valve adjustments were performed after every race in period; modern preservation requires similar diligence to prevent corrosion and bearing wear. Cooling efficiency is critical—overheating risks were documented in early 1952 tests at Monza (Ferrari Test Report 255S-TR02).
Oil Specs: Requires high-zinc mineral 20W-50 racing oil (Shell Archive 1952). Modern equivalents must meet vintage racing specifications.
Emissions: Emissions standards did not exist during this period (VCA Historical Vehicle Policy).
Power Ratings: Measured under FIA dyno standards of the era. Output varies with carburettor tuning and fuel blend (FIA Race Report 1952).
Ferrari Historical Archive: Docs LAMP/205B/001, LAMP/255S/003, 255S-ENG-01
FIA Appendix C Technical Regulations (1951-1953)
SAE International: Paper 520189 - 'Design of Early Post-War Racing Engines'
Weber Factory Technical Archive: W-36DCF Series
Shell Racing Lubricants Historical Database (1945-1955)
The Ferrari 205B, 207–255 engine family was used across Ferrari's 205 S/212 Export/255 S platforms with transverse mounting and no licensing to other manufacturers. This engine received platform-specific adaptations-increased bore in the 255 S and revised intake manifolds in the 225 S-and from 1954 the 500 Mondial adopted the Tipo 500 inline-four, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine number stamped on the right-side engine block near the oil pan rail (Ferrari Archive LAMP/ID/01). The 205B uses a 2.0L inline-four with triple Webers; the 255 S uses a 2.5L inline-six with revised cam covers. Critical differentiation from V12 units: Inline-four and inline-six configurations are longitudinally mounted in some chassis but transversely in others, while V12s are exclusively longitudinal. Service parts require production date verification—timing chains for pre-1952 models are incompatible with later 255 S revisions due to sprocket redesign (Ferrari Factory Bulletin 255S-TIM-01).
The 205B, 207–255 series' primary reliability risk is carburettor synchronization drift under high-vibration conditions, with elevated incidence during long-distance races. Factory records from 1952 noted frequent mid-race power loss due to fuel mixture imbalance, while FIA telemetry from the 1953 Targa Florio highlighted cooling inefficiencies at sustained high RPM. Vibration and thermal cycling make precise tuning and pre-race calibration critical.
Analysis derived from Ferrari technical bulletins (1951-1953) and FIA race engineering reports (1951-1953). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FERRARI 205B-207-255.
Comprehensive technical documentation and regulatory references
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