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Bulls' Guide To: Formula One FuelIt’s often said F1 uses ordinary pump petrol. It isn’t ordinary, and it doesn’t come out of a pump – but, otherwise, that statement is spot-on. Read on if you want to know how F1 fuel really works.

Heading Out On Track For Testing© Getty Images

The Nürburgring is a wonderful place to talk about fuel, because, on most days, there’s a queue of high performance road cars lined up outside the petrol station on the road opposite the Nordschleife, with first time patrons slightly puzzled that they’ve burned through a tank of petrol that is usually good for 600km in around three-and-a-half laps of the 20km circuit.

Such is the cost (in both the metaphorical and literal sense) of driving flat-out on Europe’s best-known closed toll road. Down the hill a little bit, at the GP Circuit, an F1 car has a tank probably twice the size – but it’s good for a 308km race at considerably higher speeds. Yes, the F1 car is lighter, but it’s also a marvel of thermal efficiency. Nothing comes close to matching it.

The impressive hybrid technology of the Energy Recovery System (ERS) is rightly praised for this level of economy but it’s worth remembering, that all of the energy delivered to the wheels of an F1 car ultimately comes from the fuel in the tank: the car is just incredibly parsimonious in the way it uses it.

However, the fuel itself is also clever. The Team relies on ExxonMobil and their Esso fuels brand to constantly redefine the level of performance it’s possible to achieve with the petrol that feeds our Honda RA620H power units, relentlessly developing new blends that provide more bang for our buck.

HowMuch?

When hybrid power units were introduced to F1 in 2014, the sporting regulations stipulated a maximum fuel use from lights to flag of 100kg, roughly one-third less fuel than had been used with their V8 predecessors.

The vague notion was that, as the technology matured, so the maximum would reduce, to underline the green credentials of the hybrid powertrains. The fuels and the engines have made excellent efficiency gains over the last seven years – but the fuel limit has gone the other way, first to 105kg to take account of bigger, heavier tyres and additional safety equipment (extra tethers, the Halo and its mountings etc.), and latterly to 110kg following a poor reaction to drivers employing the ‘lift-and-coast’ technique.

But, just because the car is allowed to consume 110kg of fuel doesn’t mean that is how much goes into the tank. In reality, it’s really quite rare to have the tank filled to the maximum because, quite simply, that’s not usually the fastest way to the flag.

At many races the accepted strategy will be to short-fuel – perhaps anything from 5-15kg – and take the lap time and tyre life benefits of a lighter car and accept a little bit of strategic lift-and-coast later in the race if required. Often it isn’t required as laps behind the safety car or during a VSC, or simply laps with a good tow on the straights will reduce fuel consumption.

Watch the cars in the pit lane during a red flag. If the flag follows an earlier safety car period, they’ll often be left running to burn off a few excess kilos.

New Fuel For 2021© Getty Images

DownintheCells

We talk about a fuel tank because that’s what it’s called in the Technical Regulations – but ‘tank’ gives entirely the wrong impression. In reality, what F1 cars have is a fuel sack, or fuel bladder similar to those used in military vehicles.

The regulations insist it be mounted close to the centre-line of the car and behind the cockpit and, for performance reasons it will be as low to the floor as possible. Developed by a company called ATL, it features a deformable Kevlar-and-rubber construction, it is designed to maintain its structural integrity in impacts and be highly resistant to punctures.

The way in which the fuel tank is scrunched up and pushed into the chassis makes it look like quite a basic piece of kit – but, in reality, there’s a lot going on within the bladder.

F1 cars are famed for their fast changes of direction and impressive G-forces while cornering: stability and weight distribution are critical – and wouldn’t be helped with a large mass of fuel in a half-filled tank sloshing and slopping from side to side. The tank, therefore, has a series of internal baffles fitted with one-way valves that compartmentalise the fuel and channel it down to the lowest rearward compartment. This ensures not only that the car remains stable but also, when it’s running with low fuel – i.e. in qualifying or towards the end of the race – that the fuel is placed where scavenger pumps can transfer it effectively to the collector.

KilosNotLitres

When discussing F1 fuel, litres are used for shipping, but once the fuel arrives in the garage, mass rather than volume is the measurement of choice. The simple reason is that the volume of fuel will change according to temperature, whereas the mass will not.

Chilled fuel is denser and thus, more calorific, which could provide a significant advantage back when refuelling was allowed and fuel hoses pumped fuel at a set rate of 12 litres per second (think ‘fire hose’). To this day F1’s technical regulations insist that fuel not be stored in the garage at less than 10°C below the ambient temperature, published by race control an hour before each session, and the rules also ban teams from installing chillers in the car.

Fuel for the Team is shipped in 200l drums, and DHL handle the logistics. It’s either shipped by road or via sea freight and stored at the circuit in a fuel dump, with the amount needed for the next day delivered to the garages in the evening. Before being decanted into a bowser (from which it will be pumped into the car) the fuel is tested by our ExxonMobil fuel technician for contaminants and to ensure it hasn’t suffered evaporation in transit (and thus, while still race legal, lost some of its potency). It will be checked again once it’s decanted into the bowser (to ensure there are no contaminants in the bowser). It will also be sampled by the FIA to ensure it matches the homologated fuel samples on file.

TheLab

In the back of every team garage there will be a portable laboratory, filled with equipment to study fuel and lubricant samples, ours is the ExxonMobil TrackLab. For the lubricants, the lab fulfils a useful early warning system. Excessive contaminants in an oil sample – metal shavings for example – are often a useful indicator of imminent mechanical failure, prompting teams to take action. For fuel, the primary purpose of the lab is to ensure legality, and the most useful tool for doing this is a gas chromatograph.

F1 engines run on petrol, or, in the words of the technical regulations ‘petrol as this term is generally understood’. The regulations are designed to ensure the fuel used in F1 is not entirely dissimilar to that used on road cars. It has to be formulated from compounds found in commercial fuels, has very strict regulation of impurities, and can’t contain exotic power-boosting chemical compounds.

Indeed, ExxonMobil are constantly working with Honda to test and develop new blends to deliver a little more power, or slightly better economy. Before a new fuel can be used, two separate 5l samples must be submitted to the FIA for analysis and approval. Each competitor can have up to five formulations approved for use during the season and can have a maximum of two of those available at each event.

The gas chromatograph analyses the fuel and produces a ‘fingerprint’, with each peak on the graph representing the presence and concentration of a particular compound. Our garage lab and the FIA GC will test the fuel to ensure its chemical fingerprint matches the one on file.

Max And Sean From ExxonMobil Chat© Getty Images

Upgrades

Why do we need different grades of fuel? There might be a case to match a specific fuel to the particular, but often a new fuel is homologated to match the characteristics of an engine upgrade. However, in 2020 and 2021 in-season upgrades are not possible. The essential difference between the fuel used by the RB16 and the stuff that’s sold on the Esso forecourt is a matter of tailoring.

The RB16 would run perfectly well on the stuff sold on the high street (and a road car would probably be fine with F1 fuel) but that last measure of performance comes from fitting a bespoke fuel to the specific demands of the engine. In the words of David Tsurusaki, ExxonMobil’s global motorsports technology manager, it’s the difference between wearing a suit bought off-the-peg and having one made bespoke.

“When you’re on the forecourt, you’re making a choice between two – perhaps three – fuels that will work for every road car that stops there – and that’s about it. It’s standardised by country, or sometimes by industry and you get to choose between what’s on offer.

In F1 we’re formulating a fuel to work with that specific engine, optimising the performance to the last degree.David Tsurusaki

“In the case of an elite-level motorsport like F1, we’re formulating a fuel to work with that specific engine, optimising the performance to the last degree. When the engine supplier alters the spec even slightly – perhaps a small change to the compression ratio or something of that order, it’s going to make the engine run differently and we’re going to adjust the fuel to maximise the performance.”

OutofGas

While the team are only allowed five types of fuel during the season, ExxonMobil will be sending a constant stream of formulations to Honda for testing on the dynamometer. The most promising of which will be further studied and tweaked to create a race-ready blend, mixing hundreds of compounds in just the right percentages to provide that tiny performance enhancement.

It’s one of those subsets of F1 that is an industry in itself – but front of house in the garage one drum of fuel looks pretty much like any other, and the primary concern of the race engineers and fuel technicians is usually: have we put the right amount in?

One of the things that surprises first-time guests looking at the car is that it doesn’t feature a fuel gauge. In modern F1 it would simply add unnecessary weight and, given the forces at work on the moving car, not offer any useful sort of accuracy. Instead, the bowser sits on load cells that measure the weight of fuel very accurately. The tank is drained down at regular intervals and a very precise weight of fuel is pumped into the tank as requested. Rather than weighing the fuel in the car (although we sometimes do that too) we weight what’s left in the bowser. The team will know exactly how much fuel the car consumes for any given mode at each of the circuits and fill it accordingly.

Ready To Roll Out For 2021© Getty Images

Or not. It isn't entirely unknown for a car to lose fuel pressure in qualifying because it’s been short-fuelled, or get excluded from the qualifying result because, on returning to the pit lane, there isn’t the required 1l left in the tank to be sampled by the FIA. From time to time it happens to everyone, us included. When it does it’s quite embarrassing – but this is the nature of a fast-moving qualifying session.

Sometimes there’s a problem with the bowser – Mark Webber had one of these at the 2013 Chinese Grand Prix – sometimes it’s a human error, usually caused when the Team is caught out by a last-second change in plans: engineer and driver switching back and forth between a three-lap and a one-lap plan and, with the fuel technician pumping fuel in and out and in again, with the clock ticking critical seconds away, something in the chain going awry, with the result of the driver coasting to a halt on fumes.

It doesn’t happen in race spec (anymore) because there’s a much larger margin for error; the driver has a dash delta to drive to, calibrated to the number of laps left in the race, telling him if he needs to save fuel or has no concerns. This was more of a factor when drivers had multiple engine modes to choose from.

Today, it's a simpler equation – though from time to time our race engineers might still be sweating on that final lap as much as the guy who’s fuel light comes on just as he’s cresting Schwedenkreuz.