Formula One EnginesAlthough F1 racing engines have lost some of the attractiveness they used to have when the regulations allowed more freedom, every single design currently in use is still a highly advanced piece of engineering that has required lots of time and thought. An engine is the only power source of a Formula One car - apart from the KERS systems in 2009 which are indirectly charged by the power generated by the engine - and is a structural part of the chassis.
Facts and figures
Because of the regulations and engineering optimisations, all curent engines are of a similar type, and feature the following similarities:
All F1 engines are naturally aspirated V8's of 2400cc
Engines are limited to 18,000rpm
The weight is exactly 95kg (each manufacturer easily reaches this regulated minimum weight)
Engine blocks are constructed of forged aluminium alloy, because of the weight advantages it gives in comparison to steel. Other materials would maybe give some extra advantages, but to limit costs, the FIA has forbidden all non-ferro materials.
Crankshaft and piston rods are Iron based for strength.
At its maximum pace the current V8 engines consume around 60 litres of petrol for 100km of racing.
It's not exactly known how much oil such a top engine contains, but this oil is for 70% in the engine, while the other 30% is in a dry-sump lubrication system that changes oil within the engine three to four times a minute.
Before its first track time and after each race, each engine is tested on an engine dyno to validate its performance and identify problems.
Evolution of engine design
All current engines run by the competing F1 teams are very similar due to the very stringent regulations that have increasingly come into play since 2006. Until that time, all car manufacturers involved in F1 were effectively outracing each other in a spending race. It is not a lie to claim that in the years after 1995, the manufacturer who invested most and could hire most people could produce the best engine.
Back in 1997, Ford Cosworth started a furious battle for weight reduction as their CR1 at the time was at least 25kg lighter than any other. Although they suffered some reliability problems troughout the season, the engine was an example for the others, as it allowed the team to shift ballast in the car to benefit the car's handling.
As a reaction to this weight shedding, the the 1998 Mercedes-benz engine was possibly one of the most revolutionary engines ever built, making performance gains and drastic weight cuts at the same time. It quickly proved good enough to be the basis of Mika Hakkinen's two consecutive world titles with McLaren Mercedes. When in 2000, the FIA decided to limit the use of Berillium alloys - to a maximum of 5 mass percentage - due to being poisonous in high quantities, Mercedes struggled for years to recover from that setback - they could not match anymore the power of the at that time mighty Ferrari and BMW engines.
Difference with road engines - Higher volumetric efficiency. VE is used to describe the amount of fuel/air in the cylinder in relation to regular atmospheric air. If the cylinder is filled with fuel/air at atmospheric pressure, then the engine is said to have 100% volumetric efficiency. Turbo chargers for instance can increase VE to above 100% while normally aspirated engines tipically run anywhere between 80% and 100%. In this region however, a Formula One engine usually can achieve a higher VE than normal road engines because of their highly optimised intake manifolds
- Unfortunately, from the total fuel energy that is put into the cylinders, averagely less than 1/3 ends up as useable horsepower. Ignition timing, thermal coatings, plug location and chamber design all affect the thermal efficiency (TE). Low compression street engines may have a TE of approximately 0.26, a racing engine may reach approximately 0.34. This seemingly small difference results in a difference of about 30% (0.34 - 0.26 / 0.26) more horsepower than before.
- From all that power generated, part of it is used by the engine to run itself. The left over power is what you would measure on a dynamometer. The difference between what you would measure on the dyno and the workable power in the cylinder is the mechanical efficiency (ME). Mechanical efficiency is affected by rocker friction, bearing friction, piston skirt area, and other moving parts, but it is also dependent on the engine's RPM. The greater the RPM, the more power it takes to turn the engine. This means limiting internal engine friction can generate a large surplus in power output, and where in F1 the stress is on power, on the road it is also on fuel consumption.
Engine design phylosophiesConsidering internal combustion engines (thus leaving out oscillating and Wankel rotary combustion engines), there are basically three different ways of building an engine. The difference here is how the cylinders are placed compared to each other.
- Inline engines, where all cylinders are placed next to (or after) each other are not used in Formula One since the 60's. While the engines are small, they are long and therefore require a heavy cranckshaft.
Cranckshaft design Although the V8 with the now compulsory cylinder angle of 90 degrees may look like a sawn-off V10, technically it is an entirely separate concept with its own specific requirements. The V8 has a distinct firing sequence and demands a fundamentally different crankshaft design. Whereas a 72-degree offset crankshaft was used in most V10 Formula One engines, V8 powerplants can feature crankshafts with either four throws spaced at 90 degrees or four throws spaced at 180 degrees. Standard production engines are fitted with 90-degree crankshaft variants due to their better dynamic attributes, but a 180-degree crankshaft is favoured in racing car engine design. The improved performance this allows offsets the disadvantages in terms of dynamics.
Cooling With such a low thermal efficiency, cooling of any internal combustion engine is vital for its correct operation. Basically, an F1 cooling system is the same as in any regular road car, as engine cooland and oil is pumped through a radiator to cool down before completing another cycle through the engine.
However, due to the space restrictions and aerodynamic requirements of a race car, the positioning of these components is completely different. The following shows the internals of a championship winning Renault R25 of 2005, included with its Renault RS25 engine (2). The flat panels located nearly vertically in the front of the side pods are the radiators (4). While in this picture the radiator is covered with a protective hose, it is not during running as air passes through the aluminium fins of the radiator. Their position however varies considerably in different cars as they are influenced by the aerodynamic and weight distribution requirements of a car.
Contrary to popular belief, the air inlet above the driver's head is not part of the cooling system but instead provided the engine's cylinders with air to be mixed with fuel for combustion. It is commonly thought that the purpose of this is to 'ram' air into the engine like a supercharger, but the airbox does the opposite. The carbon fibre duct (1) gradually widens out as it approaches the engine, effectively creating a venturi and a suction effect on the small air inlet. The shape of this ducts and inlet however must be carefullly designed to both fill all cylinders equally and not harm the exterior aerodynaimcs of the engine cover, all to optimize the volumetric efficiency.
Marked with (3) is the engine exhaust system while (5) and (6) identify the rear suspension that is fitted onto the gearbox.
Transmission The transmission of any car is considered to be all intermediate gears and systems to get the engine rotational power to the wheels. In reality this comes down to the gearbox and differential, which are both assembled into the gearbox casing. Just as with the engine, this casing - often made of titanium or carbon fibre - is also a structural part of the chassis and is firmly bolted onto the rear end of the engine.
RegulationsThe current regulations on Formula One engines can be summarised as follows. These specifications have become more strict during recent years in an attempt to limit costs and decrease performance. You can find an evolution of the most important regulations per era in the safety section. As this is only an exerpt of the most important regulations on engines, you would need to see the official FIA technical regulations before you start to design a Formula One engine yourself.
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