The McMurtry Spierling (featured in RET 138, April 2022) was the subject of many of the headlines from that year’s Goodwood Festival of Speed. However, among the fastest vehicles in the hotly contested hillclimb event was a van! But it is no ordinary van – Ford’s Supervan 4 (officially called the Ford Pro Electric Supervan) is a very race-focused vehicle.

The Ford Supervan 4, shown here in ‘4.2’ guise for Pikes Peak, is clearly not a conventional van, and reducing aero drag has naturally been an important aspect of its design and development
(Images courtesy of Ford)

Supervan history

Ford’s previous three Supervans have been based on sportscar chassis. The original was a combination of a production steel body and various elements of the GT40 engine, transmission and running gear. With a high centre of gravity it was supposed to be a very wild ride. The Supervans 2 and 3 were more racecar-like, with lightweight composite bodies mounted to Group C  sportscar  chassis and powered by bespoke race engines. All three vans bore a strong resemblance to the production Transit vans on which they were based, using either a production body in  the case of the original Supervan or lightweight replicas in the Supervans 2 and 3. Very loosely based on a commercially available electrified version of the Transit van, Ford’s extreme prototype Supervan 4 boasts around 1500 kW/2000 bhp and is capable of 0-60 mph times of less than 2 seconds.

 

The body styling is clearly designed to minimise aerodynamic drag while still presenting something approaching a van silhouette from the side. A front or rear three-quarter view reveals a much more teardrop form. While it is not going to be ideal for carrying builders’ materials, the Supervan 4 will have great top speed. Although it might easily be dismissed as a racecar clothed as a van, pictures of its cabin show it is based on a steel production floor pan, albeit one that carries a spaceframe/roll cage. At Goodwood, the incredible performance was key to a fast time, but the Supervan 4 has also recently tackled the ultimate hillclimb challenge at Pikes Peak in Colorado, finishing second overall in the hands of former Le Mans winner and the current Pikes Peak outright record holder Romain Dumas.

Pikes Peak entry

In RET 147 (June/July 2023), we covered the challenges of this event, and multiple winner Robin Shute said that, in selecting his engine, the benchmark to aim for is the linear response of an electric drivetrain. The chief advantage of electric drivetrains, apart from their high performance and linear response, is that their output and driving characteristics do not change with altitude,  since they do not need air in order to produce work. For entrants with an electrified powertrain, the chief powertrain-related challenge with the reduction in air density towards the top of Pikes  Peak is concerned with getting sufficiently high mass flow rates of air through the coolers in order to keep powertrain system component temperatures within limits.

The Supervan 4 has a large cooling duct directly above the front splitter, with coolers mounted directly behind the duct entry. The duct exits into the volume inside the front wheel arches. For  Pikes Peak, the van has seen some aero updates compared to the Goodwood specification and is now called the Supervan 4.2, sporting a large rear wing and a larger splitter. The Supervan 4’s powertrain is based on four electric motors that together are capable of delivering 1470 kW, almost three times the power of a current Le Mans racecar. The battery has a smaller capacity than  the road-going electric Transit, with a capacity of 50 kWh as opposed to the 68 kWh of the production van.

Battery considerations

The battery is mid-mounted for good weight distribution. It is liquid-cooled but also features a cowl exiting to a lowpressure area at the rear of the van above a full-width diffuser. At racing  speeds, the battery is good for around 35  km before needing a recharge. It could therefore have been a fraction of this size for Goodwood, and could have been further optimised for Pikes Peak in terms of weight. However, the rate of discharge is an important consideration, and the energy capacity of the battery might only have been the result of providing sufficient power with a degree of durability. The ratio of discharge power to battery capacity is known as the C-rate, a measure of discharge intensity: 1470 kW ÷ 50 kWh = 29.4 C. This means that, at full discharge rate, the  battery would last 2.04 minutes before being empty. Although it is highly unlikely that the full discharge would be done at such a high rate, a value of 29 C is very high and would result in a short battery life. In this case, ‘battery life’ means before the cells are so degraded that they require replacement.

The Supervan 4 uses extremely high C-rates (as defined by the ratio of charge or discharge power to battery energy capacity). Shown here are the charge cables next to the driver’s seat

Motors and transmissions

There are various options for the mechanical connections of four motors and four wheels. Ford, in cooperation with its technical partner STARD, has chosen to mount two motors to a  transmission and differential for each axle. STARD has been a pioneer in the electrification of rallycross, and we featured its electric rallycross powertrain in RET 131 (May 2021).  Each motor has six high-voltage connections to the inverter, indicating the use of either six phases or dual three-phase windings. The use of dual three-phase is usually done in order to maximise efficiency, performance or both. Dual three-phase can also reduce torque ripple compared to conventional three-phase winding. The paper by Yang et al* deals with this in some detail, and gives an  example of the gains that resulted from a change from conventional three-phase to dual three-phase winding based on the stator and rotor from a Nissan Leaf permanent magnet motor.

In common with the NitroCross car (RET 147, June/July 2023), the Supervan uses different transmissions front to rear. The two sets of wheels are effectively joined together during driving, so  when the two transmissions are driving at different ratios, there is a fixed ratio of front motor speed to rear motor speed (assuming no slip). The transmission on the rear axle is a two-speed unit, while the front axle has only a single drive ratio. Amazingly, the Supervan is roadregistered. An electric drivetrain is fundamentally much quieter than any IC engine and produces no emissions. Probably the noisiest aspect of this van is transmission whine. Clearly Ford doesn’t have ambitions to produce a 200 mph work van, but the Supervan is meant to show off its credentials as a  producer of impressive EVs, following on from the well-received introductions of the Mach E and F150 Lightning. In the end, Dumas in the Supervan 4.2 narrowly failed to beat Shute’s IC-engined car to victory at the first attempt. It would be a shame though if Ford didn’t return again to claim a title that is within reach of this extraordinary race machine.

Reference

* Yang, R., Schofield, N., Zhao, N. and Emadi, A., “Dual three-phase permanent magnet synchronous machine investigation for battery electric vehicle powertrains”, Journal of Engineering,  019, vol 2019, issue 17, Wiley/Institution of Engineering and Technology