The engines are installed in the Dieselmax’s chrome-moly tubular chassis at 20 degrees from horizontal, to reduce frontal area and cross section. (Jeff Bloxham photo)
The dyno tests were soon followed by the first test runs of the JCB Dieselmax streamliner, powered by two of the highly-modified 5.0L diesels. In the initial tests, conducted at the RAF Wittering airbase in the U.K. , the car exceeded 100 mph, an important milestone towards JCB’s record attempt scheduled for August at the Bonneville Salt Flats .  

The LSR engines are based on JCB’s 444-series (4.4L, four-valve) production diesel, which powers half of the company’s excavator machines. Each is fitted with two-stage turbocharging, purpose-built common-rail injection and dry-sump lubrication. JCB’s goal is to raise the FIA international speed record for diesel-powered vehicles, currently 235mph, to over 300mph.

Rear engine installation showing Garrett first-stage turbocharger, dry-sump crankcase and air inlet scoop. (Jeff Bloxham photo)

The multi-million-dollar Dieselmax project is the brainchild of JCB Chairman Sir Anthony Bamford, who believes capturing the diesel-powered LSR will help project his company’s image as a technology and innovation leader. JCB is the world’s fourth-largest manufacturer (by volume) of construction machines and the largest backhoe maker.

Putting the company into the speed-record books is “a notion that’s certainly unconventional, to say the least,” Bamford told reporters at JCB’s U.K. headquarters. To inspire his development team, Bamford gave each engineer, technician and fitter a DVD copy of  “The World’s Fastest Indian” movie. The recent film starred Anthony Hopkins as Burt Munro, a determined New Zealander who against all odds takes his home-built Indian motorcycle to Bonneville in the early 1960s.     

At JCB’s Derbyshire , U.K. , engine plant, crankshaft installation reveals large main bearings, crank journals, and overall robust construction. (Patrick Gosling photo) 

Because the Dieselmax LSR engines utilize standard 444-series grey-iron cylinder blocks, heads and bedplates, Bamford and company chief engineer Tim Leverton also reckon setting a new record will enhance the 444’s already proven reputation for robustness. That could be a useful marketing tool, as JCB hopes to enter new markets and increase sales of engines to other equipment makers.

“Land speed records are all about extreme performance, and that’s what JCB products are about, too,” Leverton said.

JCB offers three variants – naturally aspirated, turbo-intercooled with mechanical injection, and turbo-intercooled with common-rail injection. (Patrick Gosling photo)

To showcase JCB’s technology expertise and as a nod to current European trends, the  Dieselmax’s engines will be running at the Salt Flats with exhaust particulate filters – uncommon on previous diesel speed record vehicles.

To develop the LSR engines, JCB contracted Ricardo, the British powertrain R&D consultancy, which also helped design the 444 production version. Launched in 2004, the 444 series is JCB’s first in-house diesel engine. It is built in naturally-aspirated and intercooled-turbocharged versions, ranging from 70-140hp. When 444 development began in 1998, JCB and Ricardo ensured the original architecture had plenty of design headroom for the future, said Leverton.

The 444 diesel powers JCB backhoes, shown during assembly at the Rocester, U.K. , plant. (Patrick Gosling photo)

But squeezing six times the standard horsepower – 150hp/L specific output – and three times the torque out of an excavator engine proves that properly engineered diesels are capable of delivering high performance as well as high duty cycles.

“Having done the production 444, we were pretty confident of achieving the high outputs that JCB’s team calculated they’d need to push the streamliner to at least  300mph,” said Matt Beasley, Ricardo’s chief engineer on the LSR engine program. “Aerodynamics calculations mandated 1,500 hp for this car, which meant twin engines. We knew we’d need to raise cylinder pressures and injection pressure significantly, and that the 444 would be able to withstand it.”

And as JCB aims to meet Euro4 emissions (2012) with an evolution of the 444, the team decided the engines would run on a standard European low-sulfur, EN590-reference pump diesel fuel, rather than using an exotic oxygenated racing fuel as Audi uses in its LeMans-winning R10 endurance cars.

Soon after LSR engine development began in early 2005, Ricardo determined that the route to record-breaking horsepower was by significantly increased air and fuel flow, with attention paid to heat management. That meant additional displacement, higher peak cylinder pressures, vastly increased fuel delivery and a novel cooling system.

The stock 4.4L engines were bored out to 5.0L; the production block was machined where possible to remove excess weight. Two-stage turbocharging with an intercooler/aftercooler setup was employed, the water-injected aftercooler providing an additional 40-deg. Centigrade reduction in charge-air cooling.

According to Beasley, maximum boost pressure is 6 bar, compared with 2.2 bar on a stock JCB 444. “We’re flowing 3.3 tons of air per hour,” he noted. Because of the high boost, compression ratio is a mere 10.5:1. The LSR engine’s custom-made common-rail fuel system uses unique high-flow injectors, a big-bore fuel rail and dual fuel pumps. Injection pressure is 1,600-bar.

Maximum operating speed was raised to 3,800 rpm, from the 444’s standard 2,200 rpm rating -- a 170% increase over stock.

Aside from high-performance camshaft and valve springs, the LSR diesel’s iron cylinder head is stock, aside from some combustion chamber tweaks and new exhaust valves with a tougher, more heat-resistant alloy. The ultra-high pressures place commensurately extreme mechanical and thermal loadings on the aluminium pistons and connecting rods, and Ricardo has fitted special ones to cope. The pistons’ combustion-bowl geometry was refined through many hours of computer modeling and finite-element analysis, and validated in over 100 hours of dynamometer testing.

A special lightweight crankshaft spins in stock bearings within a production 444 iron bedplate. Even with some mass reduction, these are truly heavy-metal race engines. According to JCB’s Leverton, just one of Dieselmax’s engines weigh more than an entire Formula 1 racecar.

The arrow-shaped record car’s ultra-low frontal area, and the vehicle’s narrow overall cross section, meant the diesels had to be tilted 80-degrees from vertical in the chrome-moly-tubed chassis. One diesel is fitted ahead of the driver and powers the car’s front wheels; one is behind the driver and powers the rear. Their crankshafts are oriented on opposite sides of the car to help cancel the combined reciprocating forces.

Running the engines almost horizonally, and a few inches off the ground, required dry-sump lubrication. The oiling system has front and rear tanks, four scavenge sections and a single pressure section.

Dieselmax’s designers eliminated conventional heat exchangers in the cooling system, to minimize the car’s frontal area. Instead, the engines are cooled by ice water, a technique that has been employed on LSR cars since before World War II. Prior to each run a three-section, 200-liter carbon-fiber tank in the nose will be filled with 100-kg (220 lb.) of ice cubes and water, the latter to be circulated through the turbodiesels’ cooling systems and oil coolers.

With over 1,500 Nm of torque propelling the aerodynamically-slick, nearly 30-ft.-long Dieselmax, driver Andy Green should have the muscle he’ll need to break 300 mph next month at Bonneville. A veteran Royal Air Force Wing Commander, Green is no stranger to speed records, and is perhaps the best candidate for the job. He is officially the fastest man on earth, having piloted Richard Noble’s gas-turbine-powered Thrust SSC to the ultimate vehicle Land Speed Record of 763mph at Australia ’s Black Rock desert in 1997.

RAF Harrier jump-jets shared the Wittering runways with the JCB Dieselmax team during the car’s first shakedown runs last week in the U.K. (Jeff Bloxham photo)

About Dieselmax, Green said he is looking forward to piloting the British-built, backhoe-engined streamliner on the Utah salt – and raising the wheel-driven speed record for diesel vehicles.

Watch Diesel Forecast for updates on the JCB Dieselmax LSR attempt.

(Lindsay Brooke is Senior Editor of the SAE’s Automotive Engineering International magazine)