LEADING DIESEL ENGINE TECHNOLOGY TRADEMARK OF FORD TRANSIT SINCE THE EARLY DAYS
Since its early years, reliable and economical diesel engines have been a Ford Transit trademark. To this day, the Ford Transit range has delivered leading-edge diesel engine technology for the commercial van customer.The engineering chronology that has led to today's new four-valve DuraTorq turbodiesel engine family began soon after Transit's first introduction. As early as 1968, after experience of buying-in diesel engines, Ford took the decision to design its own small high-speed diesel, code-named York, and to build it at the Dagenham plant in Britain.
Diesel engines increased dramatically in popularity over the Transit's 35-year history. Now, they are cleaner and more user-friendly than ever, and account for over 96 per cent of all Transit sales.
2.4 litre York
Ford of Britain had built big, slow revving diesels for agricultural tractors and trucks since the mid-1950's and had built up a wealth of diesel expertise, but York was different and presented a major challenge. It was to be a brand new, lightweight, high-speed design and to minimise the risk Ford chose the Ricardo Comet indirect injection fuel combustion system.
Following earlier Ford practice, a parent bore block was used to achieve minimum length and maximum rigidity but many of the engine's features were novel at the time. The valve gear and the fuel injection pump, for example, were driven off the crankshaft by a toothed rubber belt rather than a chain and the undersides of the pistons were cooled by oil jets, a system previously only used in much bigger engines.
During an intensive test programme, 150 prototype engines were built and run for a total of over 50,000 hours. Some engines only lasted a very short time - victims of specially devised destruction tests - while others ran for over 1,000 hours on dynamometer test rigs.
Two power ratings of the engine went into production; a low-rated version producing 54bhp (55PS) for use in the short wheelbase models and a high-rated version developing 6lbhp (62PS) which was available across the whole range.
The York was launched in January 1972 and apart from the addition of glowplugs in 1978, served relatively unchanged until it was replaced by a new 2.5-litre direct injection (DI) engine in 1984. By that time, more than 625,000 York engines had been built at the Dagenham Engine Plant in Britain.
The popularity of diesel engines continued to grow, and by the end of the 1970s, with diesel Transit sales already running at over 50 per cent, it was apparent that more production capacity would be needed.
2.5 litre DI
With the objectives of improving durability and economy, the Transit engineering team pioneered new technology in a brand new and largely untried direct injection design. In this system, fuel is injected directly into the cylinder by a high-pressure injection pump rather than into a small pre-chamber using a lower pressure pump, as in the case of an indirect injection engine (IDI) engine. The result was a 15 per cent improvement in fuel consumption
The new engine benefited from the experience gained on York but the two had very little in common. Only two parts were carried over to the new design - the push rods that operate the overhead valves and the camshaft rear cover plate. The all-important combustion system was based on a high-swirl helical inlet port, and high- pressure fuel injection provided by a rotary pump.
Key to the success of the 2.5DI engine was the new high-pressure fuel injection system, which used a high-speed rotary pump developed by Lucas. This new rotary pump gave the required degree of flexibility on both fuel and timing control.
Compared to the original 2.4 litre IDI engine, the maximum rpm increased from 3,600 to 4,000, and peak line pressure doubled from 350 to 700 bar. The injection event had to be completed in 22/23 degrees rotation of the crankshaft versus 28/32 for the IDI.
The 2.5 DI did indeed live up to expectations and when installed in Transit and allied to new transmissions, improved fuel consumption by up to 24 per cent in short wheelbase (SWB) models and at least 20 per cent in long wheelbase (LWB) models. Fuel consumption, based on Ford's European Legislative Average (ELA) tests, improved from 27.7 to 36.2 mpg for the SWB Transit and from 22.2 to 27.7 mpg for a typical LWB model.
The considerable technical achievements of the engine were recognised almost immediately by a German energy conservation award which was soon followed by a British Design Council Award.
Apart from its improved fuel consumption, the 2.5 DI delivered an increased power output from 62 to 68 PS and improved peak torque from 134 to 143 Nm, which noticeably improved Transit's performance.
Second Generation emissions engine
Soon after the successful launch of the 2.5 DI in April 1984, the engineering focus, driven by increasing legislation and concern for the environment, moved from fuel economy to include exhaust emissions. Work started in 1985 on a low emissions engine that went into production in September 1988.
This engine saw a major breakthrough in the understanding of direct injection combustion and introduced a number of changes, including a new combustion system with a re-entrant bowl depression combustion chamber in the piston, new 'slim tip' Stanadyne injectors and the introduction of exhaust gas recirculation (EGR).
This important second-generation version of the 2.5 DI produced a maximum output of 70 PS, four per cent more power than its predecessor, and had an increased torque of 146 Nm. Due to its more complete combustion, fuel consumption also improved by a further three per cent.
First turbocharged 2.5DI
Ford pushed diesel technology even further in 1991 with the introduction of its first turbocharged version of the 2.5 DI. This was the first medium commercial diesel ever to use an electronic engine management system.
By using precise electronic timing and metering of the fuel, rather than a traditional mechanical system, this durable engine, which is still in production, was able to meet the increasingly tough emissions legislation and yet still produce 100 PS at 4,000 rpm. With a peak torque of 224 Nm at 2,100 rpm, and with 80 per cent of this figure being available from just 1,500 rpm, it is truly driver's engine.
The heart of this engine is the Lucas Diesel Systems EPIC (Electronically Programmed Injection Control) fuel injection system. With this drive-by-wire system the accelerator is not directly connected to the engine but simply by a wire which transmits a signal according to the pedal position.
This is just one of 12 readings taken from around the engine to be compared to the ideal condition and thus provide accurate fuel control. At idle, the fuel supply can be calculated and delivered for each cylinder firing, which occurs approximately 140 times a second.
At the same time a new 80 PS naturally aspirated engine was also introduced which featured a ram-type intake manifold, a twin track exhaust manifold and mechanical EGR. This engine improved the Transit 190's ELA fuel consumption to 30.4mpg.
Current diesel engine range
The engine in the current Transit dates from August 1994 when the naturally aspirated diesels were further revised to meet the latest emissions legislation. An oxidising catalyst was developed for the original 70 PS for those markets were it is required and the 80 PS engine was downrated to 76 PS to meet reduced smoke levels.
The 85 PS turbocharged engine was equipped with an EGR cooler to increase its effectiveness and it too is now available with an oxidising catalyst if required. The 100 PS turbo engine benefited from a recalibrated engine management system together with a new feature to eliminate the puff of smoke that often follows a hot start. Now that Transit has a maximum gross vehicle weight of up to 3,995kg, the 100PS engine has also been homologated to the latest 13-mode heavy truck cycle.
DuraTorq Engine Family for new Millennium
The all-new Ford Transit is powered by a family of innovative, all-new diesel engines that bring another first to the commercial van segment with advanced four-valves-per-cylinder technology. The all-turbocharged Ford DuraTorq range offers outstanding levels of performance, fuel economy and emissions capability.
The DuraTorq range is available in three 2.4-litre versions to power the rear-drive Transit - 75PS, 90PS and 120PS. Front-drive Transits, available later in 2000, will be equipped with 2.0-litre DuraTorq variants.
Highlights of the new engine range:
- All versions of DuraTorq are turbocharged with intercoolers fitted to the 90PS and 120PS versions of the 2.4-litre engine.
- Four-valves per cylinder for enhanced economy and emissions performance.
- Up to 15 per cent better fuel economy across the new range than the current
DI diesel.
- Double overhead camshaft design.
- Cast-iron block and aluminium head for strength, durability and lightness.
- Shorter, narrower and lighter than the existing diesel engines in Transit.
- Extended 25,000-kilometre servicing intervals.
- No need to add oil between scheduled services.
- Invisible levels of diesel smoke for life of engine.
DuraTorq 16-valve DI diesel has been designed to be short and compact to meet the demands of both north-south and east-west installation. It is lighter than the existing Transit 2.5-litre engine by 20kg.
DuraTorq has also been engineered to minimise the engine friction that reduces life, increases oil consumption and degrades fuel economy. This has been achieved partly through the use of lightweight, low friction, aluminium silicon pistons. Also, because there is such precise control over the combustion process, the consistently clean-burn DuraTorq prevents oil from becoming contaminated with fuel deposits.
The all-new Ford DuraTorq employs two types of rotary fuel pumps for low and higher power variants that allow fuel to be supplied to the four-nozzle injectors at very high pressure - from 900 to 1250 bar. The high pressure enables fuel to be injected in a very fine spray, which in turn gives extremely precise control over the combustion process in terms of the droplet size, the rate of fuel flow and the spread of fuel inside the cylinder. This results in optimised fuel economy while virtually eliminating cylinder-wall deposits, ensuring that new Transit will run cleaner and leaner throughout its life.
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