The Dieselmax is powered by two turbocharged diesel engines each pumping out 750bhp, making it twice as powerful and twice as fast as a Formula One race car (despite weighing almost twice as much). The engines are modified versions of the JCB444 production engine found in JCB diggers and will run on standard diesel.

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“This is the most amazing race car to be built in Britain for a decade,” said Green. “It is an extraordinary challenge. What we have is basically a digger engine that has been made into the most powerful car engine in the world.”

During Speed Week the flats are divided into two areas: a 10-mile-long straight for speed trials and an oval or circular track for distance runs, which are typically between 10 and 12 miles. The straight is marked with a broad black line down the centre with measured mile sections after the second mile marked out carefully with cones.

The first run doesn’t go as planned. Although the JCB reaches 159.464mph with a peak speed of 163mph, the turbo boost from the rear engine fails to kick in. The next day they try again but the rear engine stubbornly refuses to fire. And the next.

By Tuesday the team thought they had cracked the problem: they had changed the engine management system to reduce the fuelling of the front engine in first gear, thereby increasing the load to the rear engine, which would hopefully engage the turbo. It worked — up to a point. The rear engine turbo kicked in as planned, but the front engine didn’t.

By Wednesday the team were getting worried. The record attempt is due to take place tomorrow and with just five days to go and the engine misfiring there is little time to get it right.

Sophy Gardner, Green’s girlfriend and a trained pilot, is on hand to lend moral support. “She is used to me doing stupid stuff,” said Green. “She’s only frustrated that she can’t be there for the actual record attempt. It’s very hard to explain the excitement of all this. It’s nothing like driving a fast car on the road. There is a real camaraderie. Everyone is willing to offer tips and help out where they can — it’s a sort of pioneering spirit.”

Just as well, because at time of going to press the team were still finding and fixing gremlins in the works. “We’ve discovered what the problem is with the rear engine and the front engine and we have made the necessary adjustments,” said Green.

“No car ever works first time and you have to remember that we have encountered problems that have never been seen in a car that has never been built before in a place where some of the team have never worked before.

“It is intellectually challenging and emotionally scintillating, but when it all comes together at the right time I know that we can do it.”

To find out if he is right you’ll just have to wait until the first official record-breaking attempt tomorrow.

Team spirit

There’s half a century of experience between the youngest and the oldest members of the JCB team. Annie Berrisford, 24, a mechanical engineering graduate from Derbyshire who has spent a year working at JCB after university, is one of only two women in the team. “My father restores old cars and I was always working with him in the garage as a teenager. I’m not really one for skirts and dresses.”

At the other end of the age scale, 74-year-old Ron Ayers has created the aerodynamic shape of Dieselmax. He was also the man behind the Bristol Siddeley Bloodhound missile, the UK’s main air defence weapon during the cold war. Ayers became a pensioner in 1997 when taking charge of the aerodynamic test programme for Green’s ThrustSSC world record car.

With the kind of determination that inspired grandfatherly Burt Munro to set a world record on the salt flats on his Indian Scout motorcycle — played by Anthony Hopkins in the film The World’s Fastest Indian — Ayers resolves never to put away his slide rule.

“I have no intention of retiring. As long as I have something to contribute I will continue.”

The engine that picked up speed late in life

The diesel engine was invented by Rudolf Diesel in 1892 and the first diesel production car was built in 1936. It wasn’t until the 1970s with the introduction of turbochargers that the performance of diesels improved enough to see speed-record attempts in machines such as the UFO diesel driven by Fredrick Lavell. Even so, the acceleration of this 1970s classic was dismal by modern standards. It would clock just 45mph on a quarter-mile run and took 10 miles for it to reach its maximum speed of 129mph. Then in 1973 came the Thermo King Streamliner (above). Driven by Virgil W Snyder, it smashed the 200mph barrier and later achieved 235.756mph on August 25. Since then no competitors have come close — until the Dieselmax.

JCB Dieselmax

Engine: Twin 5000cc turbocharged JCB444, four cylinders
Power: 2 x 750bhp @ 3800rpm
Torque: 1105 lb ft @ 2000rpm
Transmission: Two six-speed manual gearboxes
Weight: 2,700kg including fuel, water coolant and driver
Fuel capacity: 9 litres
Maximum speed: 300mph+
Brakes: carbon brakes plus driver-activated engine braking and two parachutes
Tyres: 23x15 Goodyear
Drag coefficient: 0.174Cd