Cosworth DFV: The Engine That Defined an Era

The Ford-Cosworth DFV engine is, without question, one of the most significant pieces of engineering to ever grace the world of motorsport. Its name is synonymous with an era of Formula 1, a period where its distinctive V8 howl echoed around circuits worldwide, propelling legendary drivers to victory. With an astonishing 155 Grand Prix wins to its name, spanning from 1967 to 1985, the DFV didn't just participate; it dominated, becoming the benchmark against which all other engines were measured. But what made this engine so exceptionally successful, and what does it take to keep such a historic powerplant alive and thrumming today?

The Genesis of a Legend

The story of the DFV begins with a collaboration between Ford and Cosworth Engineering, founded by Mike Costin and Keith Duckworth. Following the success of a smaller Ford Formula 2 engine, Lotus Chairman Colin Chapman convinced Ford to finance the development of a three-litre, eight-cylinder Formula 1 engine. The deal granted Lotus exclusive use for the initial year, a strategic move that would see the DFV debut in the iconic Lotus 49 at the 1967 Dutch Grand Prix. The engine, a marvel of lightweight aluminium construction, was designed by Keith Duckworth, with its V8 configuration and four valves per cylinder contributing to its impressive power output and efficiency. The initial investment for this groundbreaking engine was a mere £100,000, a sum that would prove to be one of the most astute investments in motorsport history.

Technical Prowess and Evolution

The early iterations of the DFV, as fitted to Jim Clark's Lotus 49, produced a formidable 405bhp. However, the engine's development was a continuous process. By the end of its F1 career, the DFV was pushing out nearly double that power. Key to its success was its innovative design:

• V8 Configuration: A 90-degree V8 layout provided a good balance of power and compactness.
• Double Overhead Camshafts (DOHC): Operating four valves per cylinder, this allowed for superior breathing and combustion efficiency compared to older two-valve designs.
• Aluminium Construction: This not only kept the weight down to a remarkable 168kg but also provided exceptional rigidity, allowing it to be used as a stressed member of the chassis. This integration was revolutionary at the time, contributing to lighter and more agile car designs.
• Fuel Injection: Initially Lucas mechanical fuel injection, this system was highly advanced for its era, delivering precise fuel metering for optimal performance.
• 'Supersquare' Design: The cylinder bore was wider than its stroke, a configuration that contributed to its high-revving nature and power delivery.

The DFV wasn't just a one-trick pony; it spawned successful derivatives like the 3.9-litre 'DFL' for endurance racing and the turbocharged 'DFX' for IndyCar. Its versatility and inherent strength meant it wasn't confined to F1, finding success in various other racing disciplines, including Le Mans and Indy 500.

The Era of DFV Domination

The DFV's impact on Formula 1 was profound. After its debut win with Jim Clark, Ford made the engine available to other teams in 1968. This democratisation of performance meant that the DFV became the de facto engine for most of the grid, barring Ferrari. For over a decade, a DFV-powered car was almost guaranteed to be a championship contender. Drivers like Jackie Stewart, Niki Lauda, James Hunt, Mario Andretti, Nelson Piquet, and Alan Jones all secured World Championships at the wheel of DFV-powered machines. The engine's reliability and consistent power delivery made it a favourite, even as turbocharging began to emerge as a new technological frontier. While turbo engines eventually surpassed the naturally aspirated DFV in raw power, the V8's legacy was already firmly cemented.

Living with a DFV Today: The Racer's Retreat

Owning and maintaining a DFV in the modern era is a labour of love, as exemplified by Peter Brennan and his 'DFV250', currently residing in an Arrows A1-'06'. Brennan, a multi-talented mechanic, relies on the wisdom of experts like Phil Reilly of Phil Reilly Engineering in California, a veritable guru of Cosworth engines. The process of keeping a DFV race-ready is intricate and demanding, far more so than for simpler engines.

Care and Feeding: The DFV Maintenance Regimen

The meticulous attention to detail required for DFV maintenance is best illustrated by Peter Brennan's practices and advice from specialists like Phil Reilly and Geoff Richardson Engineering:

Routine Checks and Fluid Management

Oil: The lifeblood of the DFV. Kendall 20/50 mineral oil with a high zinc content is favoured for its benefits to cams and followers. The oil filter (Cosworth Part #PP0404) needs changing every 300 miles, and oil levels must be checked religiously, as the engine can consume up to 4 quarts every 100 miles. Crucially, the oil temperature must be maintained between 90-100°C at the pressure pump inlet. The engine should not exceed 7000rpm until the oil reaches at least 50°C. The engine must never be allowed to suck air, as this can lead to catastrophic bearing failure at high revs.

Fuel System

The Lucas fuel injection system requires a constant fuel pressure of 120psi. The fuel filter should be replaced every 500-700 miles. For starting and low-speed operation, an electric fuel pump is used, with a mechanical pump taking over on-circuit. Injector nozzles should seal at 50-65psi. Peter Brennan adds a small amount of light engine oil to the 100 octane avgas (a ratio of 2 ounces per 5 gallons) to extend the life of the metering unit, fuel pumps, and valve guides.

Ignition and Spark

The '250' uses the Lucas 'Opus' ignition system, with timing typically set at 38-40 degrees BTDC. The system requires a negative earth and rev limiters set to 10400rpm. Bosch surface discharge spark plugs are used, with a life expectancy of 3-4 race weekends. Careful attention must be paid to shutdown procedures to avoid voltage spikes that can damage the delicate spark boxes.

Mechanical Installation and Cooling

Engine mounting bolts for the valve cover, made of magnesium, require careful torqueing to 16-18 ft-lbs to prevent damage. The throttle slides feature unique Cosworth over-centre return springs to ensure positive closure. The cooling system must be free of airlocks, using a 50/50 mix of water and glycol. Water outlet temperatures should be monitored at the rear of the heads, ideally between 90-110°C.

Storage and Regular Exercise

When not in use, the DFV needs regular attention. It should be turned over by hand once a week with the fuel pump engaged. This circulates fuel to prevent corrosion and keeps seals from sticking, while also preventing valve springs from remaining fully compressed for extended periods.

Performance and Rebuild Intervals

Running a DFV at its peak, around 11000rpm, is a demanding affair, with rebuilds potentially needed every 3-4 hours of use, costing upwards of £10-15,000 for a complete refresh. However, for vintage racing, operating at around 10000rpm significantly extends the engine's life, offering 15-20 hours between rebuilds. Geoff Richardson Engineering notes that a routine rebuild for an engine limited to 10000rpm typically involves stripping, crack testing, inspection, reassembly, and dyno testing, with valve springs replaced every time. Pistons and valves are assessed on condition, with new rod bolts, bearings, rings, and seals fitted as standard.

The Driver's Perspective

Driving a DFV is an experience unlike any other. Peter Brennan describes its power delivery in three distinct phases: a surge at 5500rpm, another at 7000rpm, and then a ballistic explosion at 9000rpm, demanding constant gear changes and a keen ear for the engine's symphony. While not possessing the low-end torque of an F5000, skillful throttle modulation allows drivers to manage wheelspin and maintain rapid progress. The sound of a DFV at full song, reaching speeds of over 180mph, is described as an unbelievable and relished experience.

The DFV in Modern Racing

Even today, the Ford-Cosworth DFV remains a popular choice in historic racing. Its power, smooth delivery, and relative reliability compared to contemporary engines make it a joy to drive and a competitive proposition. Bruce Allison, who raced Cosworth-powered Marches, attests to the engine's enduring appeal, predicting its popularity for at least another 50 years.

Key Figures and Legacy

The Ford-Cosworth DFV's impact is undeniable:

Frequently Asked Questions

How much power does a Ford Cosworth DFV have?

The original DFV produced around 405bhp, but through development, later versions could produce upwards of 500bhp. In modern historic racing, engines are typically tuned to produce around 470bhp at 10500rpm.

Why is the DFV considered the most successful engine of all time?

Its unparalleled record of 155 Grand Prix wins, numerous World Championships, and its dominance across multiple eras of Formula 1 solidify its status as the most successful racing engine ever built. Its influence extended beyond F1, with successful variants in other motorsport categories.

What is involved in maintaining a DFV engine?

Maintaining a DFV requires meticulous attention to detail, including regular oil and filter changes, precise fuel system management, careful ignition timing, and adherence to specific operating temperatures. Rebuilds are frequent and costly if the engine is pushed to its limits.

Can you still buy Ford Cosworth DFV engines?

Yes, Cosworth Engineering still offers parts and even new engines, though they are highly sought after and expensive. Specialist engineering firms also rebuild and supply these engines for historic racing.

What is the firing order of a Ford Cosworth DFV?

The firing order is 1-8-3-6-4-5-2-7.

Conclusion

The Ford-Cosworth DFV is more than just an engine; it's a legend. Its engineering brilliance, coupled with the skill of the drivers and teams that wielded it, created an era of motorsport history that continues to captivate. The dedication required to keep these magnificent machines alive today is a testament to their enduring appeal and the indelible mark they've left on the world of racing.