Diesel goes for record

Diesel goes for record

Tom Shelley reports on a land speed record attempt with a direct payback for users of commercial diesel engines

Tom Shelley reports on a land speed record attempt with a direct payback for users of commercial diesel engines

The JCB DieselMax diesel land speed record attempt car is powered by only two slightly modified versions of the company's conventional JCB444 engines.

With 50% more rpm and five times the power output of the power plants used in the CX, 2CX and 3CX backhoe loaders, twin JCB 444 LSR variants are expected to propel Wing Commander Andy Green to 300mph at Bonneville Salt Flats some time this August.

But much more importantly for JCB, Group Engineering Director Dr Tim Leverton revealed that the stretching exercise has resulted in technologies that are expected to result in a revolutionary four cylinder engine to eventually replace six cylinder engines currently powering some of the larger JCB products, significantly reducing both weight and fuel consumption.

Dr Leverton explained that the company went into making its own engines because with 10 ten per cent of the world market share it made sense to do so, especially when original supplier Perkins Engines was bought by competitor Caterpillar. At the same time, vertical integration is part of the JCB philosophy. "65 per cent of JCB products we make ourselves which is where our profitability comes from."

The stretching of the engine was conducted in conjunction with Ricardo, who were the original 444 engine development partners. Dr Leverton said that for the LSR variant, "We are pulling everything in we can, but in doing so we are learning things about the engine that we can apply to our standard engine. Ricardo Project Director Matt Beasley showed us the much larger piston combustion bowl, which increases engine capacity from 4.4 litres to 5 litres and is optimised for increased fuel flow. He said, "Ricardo has done a lot of work on diesels for performance applications. Most of the technologies are the kinds of things we need to do for high efficiency, low emission engines." The LSR has twin stage turbo charging to 5.2bar with inter stage and after cooling instead of the 2 bar single turbo charging in the production engine. The large, quiescent combustion chamber has an overall reduced compression ratio and "specific features" to reduce the risk of thermal damage to the combustion chamber components. Piston cooling is improved by doubling the size of the oil cooling jets and adding supplementary cooling jets which together increase cooling oil flow by about 600 per cent. A new, fully machined connecting rod includes a significantly enlarged small end bearing. Mr Beasley told us the rods were, "Lighter, made of better materials and of stronger design." The camshaft has been lightened by drilling a larger hole down its centre and applying a "Super finish" to the outside. A new cam profile allows running at up to 3800 rpm instead of 2200 rpm. The common fuel rail runs at 1600 bar, not unusually high for passenger cars, but unlike theirs, is 50mm in diameter.

Although diesel engines are about 30 per cent more fuel efficient than spark ignition engines, they need 50 per cent more air, which means that the DieselMax car has an intake airflow of nearly five tonnes per hour. Radiators would cause too much drag so Ricardo has designed a cooling system based round a 200 litre water and ice tank in the nose, the same cooling technology used by the Mobil Railton Special driven through the flying mile by John Cobb at a speed of 394mph in 1947. The supercharged diesel record, incidentally stands at 235.756 mph and was set over a measured mile on August 25th 1973 by Vergil W Snyder in his Thermo King Streamliner also at Bonneville. JCB Chairman Sir Anthony Bamford said he got the idea of attempting the diesel land speed record watching one of the first prototype engines on a test stand at Ricardo, as a way of promoting the engine.

The company produced some 10,000 machines last year powered with the own engines and intends to increase this to 25,000 this year as well as sell 20 per cent externally for use in work boats, fire retarded applications on oil rigs, pump sets and 50 to 100kVA generators. The engine is optimised for construction equipment with a high, low end torque and a very stiff bottom structure that enables low noise emissions. The LSR engine has a standard engine block, cylinder head and bedplate, although Dr Leverton admitted to "Some thinning" to improve heat transfer to the coolant.

Two six speed gearboxes are employed, one for each engine. The engines are placed on their sides, inclined at 10 degrees to reduce the effective cross section of the car and use dry sumps. Each gearbox is mated to its engine using a JCB designed stepper gearbox arrangement with oil immersed multi-plate clutch packs from 3CX backhoe loaders. A torque tube encloses the gearbox and connects the final drive to the rest of the driveline. Gear shifting in both boxes is synchronised and controlled electronically with shift actuation via steering wheel mounted paddle switches. The only other connection between the two engines and transmissions, one of which is in front of the driver and one behind, is through the ground under the wheels.

JCB products are not normally noted for their high road speeds, and it is said that Gary Major, head of JCB Industrial Design and JCB Designer Mike Turner spent a day at the home of Richard Noble, who led the Thrust SSC project, before they put their first line on a CAD screen. Ron Ayers, who did the CFD modelling for the Thrust SSC did all the CFD modelling using Fluent. The car has never been in a wind tunnel either full size or half scale. Being 9091mm long, somewhat larger than the average F1, and intended to go somewhat faster, there is no wind tunnel in existence with a fast enough moving road. Dr Leverton said that the company, "Uses CFD a lot in our machines to model our standard engines." Design of the rest of the car was with UG NX2 CAD as is used in the rest of the company backed by UG Teamcenter for project management and collaboration. May 2006 will see lifing runs, with UK runway tests in July. There is no spare car. When asked, Dr Leverton said that, "Plan B would be to mend it." A 160 HP son of the LSR 444 engine is targeted to make its commercial debut in the bottom end of the Fastrac range, replacing the present Cummins 6 cylinder engine.

JCB
UGS
Fluent

"Ricardo has done a lot of work on diesels for performance applications. Most of the technologies are the kinds of things we need to do for high efficiency, low emission engines"

Eureka says:

Pointers

* The standard JCB engine has been stretched for the record attempt to run 50 per cent faster and deliver a five-fold enhancement in power

* The technologies developed for the record attempt engine are to be used in a four cylinder engine that will replace a present six cylinder engine with consequent savings in weight and improvements in fuel economy

Author
Tom Shelley

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