Formula 1 and IndyCar are probably the two biggest and best-known single-seater championships in the world. But although the cars may look broadly similar, the two series are very different, so we thought we’d take a look at some of the key differences in the machinery.
The Formula 1 World Championship has been running uninterrupted since 1950. In 2021, 20 drivers from 10 teams will compete in 23 races around the world, the majority of which are purpose-built road courses, with a few street tracks thrown in for good measure.
F1 is now well into the engine formula first introduced for the 2014 season which features 1.6-litre V6 turbo engines assisted by a hybrid system which combined means a total power output of around 1000bhp. The hybrid system recovers energy in two main ways - the MGU-K, and the MGU-H. The ‘K’ part stands for kinetic and recovers energy that would otherwise be lost through braking, while the MGU-H (heat) draws thermal energy from the exhaust system. Along with the energy store (ES) and control electronics (CE), these make up the Energy Recovery System (ERS); add in the internal combustion engine (ICE) and the turbocharger (TC) and you have a complete F1 power unit. Theoretically they’re allowed to rev as high as 15,000rpm, but restrictions on fuel flow, reliability concessions, and the general power curve of the unit mean that drivers usually change gear below 12k.
Across the 23-race 2021 season, each car may use a maximum of two energy stores or control electronics, and three each of the ICE, TC, MGU-K, or MGU-H elements. Any more than this and drivers will have to take grid penalties.
At the moment the 10 F1 teams are supplied by four different power unit manufacturers: Mercedes, Honda, Renault, and Ferrari - although Honda is leaving at the end of the 2021 season, with Red Bull set to take over the project. Development of the power units is being frozen for 2022 ahead of a yet-to-be-revealed new formula for 2025.
The gearbox comprises eight forward gears (with a fixed ratio across the whole season) and a mandatory reverse. They are of course semi-automatic and seamless shift, and must last for six consecutive events - if any are changed before that then yup, you’ve guessed it, grid penalty.
Aerodynamic regulations across the different areas of the car are tightly restricted by height, width and location boundaries. But within these small boxes of possibilities, teams are more or less free to do what they like. The quest for downforce is the source of much of the R&D work for teams and even when the regulators attempt to reduce the amount of downforce produced and slow the cars down, it’s usually not long before the teams manage to recover it.
In an effort to level the playing field and prevent money from being such a key factor in how successful a team is, for 2021 the sport has also introduced a cost cap of $145 million per year, which will be further reduced over the coming seasons (although it’s worth noting that certain things such as driver salaries or marketing aren’t subject to the restrictions). There are also other development restrictions - the higher a team finishes in the championship, the less time they’re allowed to spend testing aerodynamics in the wind tunnel or through CFD simulations.
All that complex aero creates a lot of aerodynamic wash, or dirty air, which makes it difficult for the cars to follow one another closely at high speed. To combat this, F1 has an overtaking aid called the Drag Reduction System (DRS). When a driver is within one second of the car in front, they can press a button that opens a slot in the rear wing, allowing it to travel faster in a straight line and making it easier to overtake.
The total weight of the cars is mandated to be a minimum of 752kg, a hefty increase from the 605kg cars of little more than a decade ago. Part of this is down to the increased mass of the hybrid systems, but also improvements in safety, such as the Halo device which extends over the cockpit and protects the driver’s head from foreign objects in a crash.
The steering wheels are very complicated with a considerable number of buttons, dials, thumb wheels, paddles and combinations which are used to adjust things such as brake balance, differential settings, and engine modes, as well as a screen display for viewing information and data. Carbonfibre composite brake discs squeezed by a conventional hydraulic caliper are used with the rear ones assisted by the ERS. Tyres are supplied by Pirelli, with five dry-weather compounds available across the season, three of which are available to use at any given race, depending on the circuit characteristics. There’s also an intermediate tyre for when the track surface gets a bit wet, and a wet weather compound in case it’s really chucking it down.
Pit stops are mandatory during races thanks to the need to use two different dry compounds of tyre in a race. There’s no mid-race refuelling and as a result the pit stops have become blink-and-you’ll-miss-it fast - during the 2019 Brazilian GP, Red Bull managed to change all four tyres on Max Verstappen’s car in just 1.82 seconds.
Unlike F1, the IndyCar grid runs the same chassis and aerodynamic kit, with power coming from one of two engine manufacturers - Honda or Chevrolet. In 2021, IndyCar is running 17 races at 15 rounds in the USA, with double-headers at Texas and Detroit. Grid sizes are a bit more fluid than in F1, with most races featuring 24 or 25 drivers, which balloons up to a field of 33 for the blue riband event that is the Indianapolis 500. Teams run anything from one to six cars and teammates usually don’t share the same livery. Some drivers even have a different colour scheme for each race.
The carbonfibre Dallara DW12 chassis is used by the entire field. The cars run 2.2-litre twin-turbocharged V6 engines from Honda and Chevrolet and produce between 550bhp-700bhp depending on the amount of boost used and the type of circuit being raced on (generally speaking it’ll the lower power figure on ovals for reasons of durability and safety). In 2023, this will all change - engine size will go up to 2.4-litres, while the addition of KERS will add a hybrid element as power goes up to 900bhp.
The gearboxes are six-speed, semi-automatic paddle shifts with a reverse gear. Tyres are supplied by Firestone and, like F1, feature different dry weather compounds. There are also wet tyres available for road and street courses, with no wet running at all allowed on oval circuits. On road and street courses each driver must use both compounds at least once. Brembo brakes are used across the field, with different numbers of pistons depending on the type of track.
However, just because the cars all have the same chassis and aero kits it doesn’t mean the cars are all identical. Teams are allowed to build and develop their own parts such as the brake ducts and certain suspension components, with the dampers being a particularly key area of potential improvement.
This is critical when you see the type of circuits that IndyCar races on a wide range of circuits, with drivers having to master undulating road courses, bumpy rough-and-ready street courses, and high-speed ovals across the course of a season. For each of these, the specification of car is different - so the amount of power, the brakes, the aero kits and weight all change. This is to react to the unique characteristics and demands placed on the cars. So in terms of the latter, on small ovals, street and permanent tracks the weight is 730kg, while on speedways it is 716kg (excluding the driver). The aerodynamic kits also change drastically for superspeedways, with the multi-element front and rear wings being replaced by thin aerofoils to minimise drag and maximise top speed.
Like F1, IndyCar has an overtaking aid - the push-to-pass system (again, only on road and street courses), where drivers can press a button on the steering wheel to get a 60bhp boost of power. However, unlike F1, its usage is much less restricted. Drivers can use it to attack or defend, on any part of the circuit they want to, and for as little or as long as they want to (up to a maximum of 15 seconds in one push). The only limitation is the number of seconds they’re allowed to use it in a race, which changes from circuit to circuit but is normally around the 200 mark.
Drivers also have to be wary of how much fuel they’re using because refuelling is a key strategy element in IndyCar. Drivers will usually have to make two or three stops for fuel during a race and, depending on the freqeuncy and timing of a caution period, fuel-saving is a key weapon in the driver’s armoury. Because of the need to refuel and a limit on the number of people allowed to be involved in a stop, a normal pit stop in IndyCar can range anywhere from six to 10 seconds.
As in F1, IndyCar also recently introduced cockpit safety measures, with its Red Bull developed aeroscreen designed to deflect debris away from the drivers head at speed.
Although an IndyCar is around 70cm shorter than an F1 car and 20kg lighter, the simpler aero means they’re much slower around a typical track. For comparison, at the Circuit of the Americas in Texas in 2019, the pole position time for Formula 1 was a 1:32.029, while earlier in the year the quickest IndyCar lap was a 1:46.018. F1 cars top speeds are limited by the circuits and draggy aero, meaning the highest speed you’ll see in a season these days is generally around 220mph with the assistance of slipstream and DRS, while an IndyCar in superspeedway setup will nudge 240mph in clean air, despite just having a smidge over half the horsepower.
Another key difference between the two is that F1 cars have power steering, whereas IndyCar’s don’t, making for a more physical driving experience. Romain Grosjean recently made the switch from F1 and just two races into his IndyCar career declared that a race around the bumpy streets of St Petersburg, Florida was the hardest he’s ever done.
Although they may look similar, IndyCars and F1 cars are very different beasts, designed with differing priorities in mind. IndyCar races on a wider range of tracks and the cars can change significantly depending on the circuit. F1 is much more standardised race-by-race, but the innovation and development of the cars create more diversity among the teams and, around a typical race track, makes them the fastest racing cars in the world. Both series produce phenomenal racing and at the end of the day, that’s what matters the most.
This article was updated by Dan Thorn on 06/05/2021