Diesel engine is readied for record attempt

When JCB originally approached Ricardo in 1998 with a brief to design a totally new engine to power JCB products, there were four design targets.

As the finishing touches were being put to the JCB Dieselmax speed record contender - which Andy Green soon will begin testing in the UK - the JCB444-LSR (land speed record) engines that will aim to propel him to speeds in excess of 500km/h were signed off at Ricardo's Shoreham-by-Sea premises last week after reaching their target power output of 750bhp each.

Six LSR engines, which are direct descendants of the JCB444 diesel engine that powers the company's famous backhoes and Loadall telescopic handlers, have been prepared for the record attempt that is scheduled to happen at the world famous Bonneville Salt Flats in August.

When JCB originally approached Ricardo in 1998 with a brief to design a totally new engine to power JCB products, the design targets called for robust construction; a long stroke to facilitate high torque at low engine speeds; reduced noise levels; and future proofing for the next steps in emissions legislation.

"These were worthy aims for an engine intended, among other things, to use its weight to balance a backhoe, but on the face of it some of them were contradictory to development of the unit as a racing engine", said Ian Penny, Ricardo's Global Director of Diesel Engines.

Therein lies the technological fascination and validation inherent in the JCB Dieselmax programme, which was built around the racing engine using the standard block, cylinder head and bedplate (albeit with some lightening) in order to showcase the extraordinary versatility of the standard engine.

"Our intention all along was to use a standard block, cylinder head and bedplate", explains Dr Tim Leverton, JCB Group Engineering Director with board responsibility for JCB Power Systems.

"I wanted it to have exactly the same fundamental architecture as the JCB444 engine".

The standard engine - the only one of its kind in the world designed specifically for its industrial application - has already set new marks for power output and reliability in service.

During the course of development of the LSR version, the standard engine demonstrated the ability to cope with the very high cylinder pressures generated by the two-stage turbo-charging necessary to boost the normal 120bhp power to the 750bhp that will be needed to push the twin-engined JCB Dieselmax streamliner beyond 500km/h.

"The whole project has been a fantastic engineering challenge", Penny continues.

"Once we had defined the engine concept in January 2005, our effort then focused on validating and refining that concept".

"Initially we tried single and then two-stage turbo-charging, having taken the view to avoid more esoteric methods of boosting power".

"As a result we have advanced technology in the engine, particularly in the combustion chamber design where Ricardo has deep experience, that will filter through to JCB products, and to proprietary production cars, within the next five to 10 years".

Matt Beasley, Ricardo's Project Director with specific responsibility for the JCB444-LSR engine's development, summarises the challenge thus: "The greatest challenge was how to get sufficient air and fuel into the engine to increase its power, and to manage that air and fuel flow and the associated heat generated by two-stage turbo-charging at 6bar".

Besides the block, head and bedplate, the JCB444-LSR engine also uses the standard valve train, albeit with stronger springs and different exhaust valves.

The crankshaft and camshaft are lightened, while the pistons and connecting rods are bespoke.

"One of the major areas of development has been the piston design", Beasley adds.

"The engine places very high mechanical and thermal loadings on the aluminium pistons, and we spent a lot of time refining the design".

"Aluminium normally degrades rapidly with such high temperatures".

"We experimented with a number of profiles".

"Since then we have focused on refining the other key areas - the lubrication and fuel systems".

"The former is totally new as the engine is inclined at 10 degrees from the horizontal for optimum installation in the car".

"There is a lot of oil flow, up to six times what you would expect in a normal diesel engine and the oil circulates around the engine every five seconds".

"The fuel system is also remarkable".

"We have achieved 750bhp after going to gold fuel pumps in place of the previous red pumps, and by very careful attention to the injection system".

"We are putting a tremendous amount of fuel through very small orifices in the injectors, and are doing so at massive pressure - 1600bar - hence the magnitude of the engineering challenge in that area".

"Test 'mule' engines ran for as long as 12 hours during the development phase, and some were stressed to destruction in order to see where the limits of individual components were".

"They were impressively high", Penny says".

"The definitive JCB444-LSR engine displaces 5 litres, weighs 382kg (dry), and produces 750bhp at 3800rev/min on a relatively low 10.5:1 compression ratio and in excess of 1500Nm of torque at 2200rev/min.

"I am confident that the JCB Dieselmax will easily be the cleanest and most efficient land speed record car ever built", Ian Penny adds.

"The car has twice the power and more than four times the weight of an F1 car, yet half the fuel consumption".

"There is perfect synergy between Sir Anthony Bamford's avowed aim of showcasing British engineering and Ricardo's corporate ambition to promote the fuel efficiency and emissions cleanliness of diesel technology, particularly in the United States".

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