By the mid-1990s the Rover Group was looking to rationalise its engine ranges and produce new designs that would be able to meet emissions legislation for the foreseeable future. The recently released K-Series petrol engine range would be extended to cover that sector, but Rover had no in-house diesel engines suitable for both its cars and its 4×4s. The 300Tdi could not be fitted to any of the car range and was about to fall foul of the upcoming Euro III emissions standards. The existing L-Series 2-litre diesel was not suitable for use in Land Rover products and could not be developed into such a unit.
It was decided to design a new diesel engine family that could be produced in various capacities and states of tune suitable for all of Rover’s needs. The development was codenamed Project Storm and design responsibility was given to Land Rover who were to build the engines. The result was a range of engines using the L-Series as a base—the bore/stroke dimensions were the same and the Storm engine used the same piston and connecting rod assemblies. The Storm utilised Electronic Unit Injection by Lucas (at the time this technology was rare on small-capacity engine, being used only on large commercial vehicles) and a cross-flow aluminium alloy cylinder head on a cast-iron block. The designers had aimed at increasing servicing intervals so the engine incorporated both conventional and centrifugal oil filters. The electronic systems included an ‘anti-stall’ system to allow heavy loads to be started from rest at idle speed and two programmed operating modes for road and off-road use. The overhead camshaft (operating both valves and the unit injectors) was chain-driven. The Storm design encompassed 4-, 5- and 6-cylinder engines (of 2, 2.5 and 3 litres respectively).
In the event the takeover of the Rover Group by BMW, who brought their own range of diesel engines, made the Storm engine largely redundant. Only the 5-cylinder version made it to production as the powerplant for the Defender and the new Discovery Series II as the ‘Td5’ in 1998. Offering more power and greater refinement than the 300Tdi the Td5 greatly improved the appeal of the Discovery but caused concern amongst many operators of the Defender due to its electronic engine management systems which were considered to be less reliable and more difficult to repair ‘in the field’ than the mechanical injection systems used on previous Land Rover diesel engines. In deference to these concerns (including those voiced by the British Army) Land Rover kept the 300Tdi in production for fitment to special-order vehicles (see above). It transpired that the Td5’s electronics were highly reliable. Early engines suffered two isolated mechanical failures—sudden and complete failure of the oil pump drive and ‘cylinder head shuffle’ caused by weak retaining studs. Both these faults were fixed within 2 years of the engine starting production and the Td5 is now considered highly reliable. In 2002 the engine was improved to reach Euro 3 antipollution stage, and an EGR valve system was introduced. Electronics were also updated to improve the low-speed throttle response which had been prone to producing a jerky power delivery in off-road or towing situations.
The engine has proved itself on numerous expeditions in hostile terrain (including Land Rover’s own G4 Challenge). The engine’s mechanical strength and electronic control systems makes the Td5 much more tuneable than the older engines. Numerous aftermarket companies produced tuning upgrades offering as much as 220 horsepower (164 kW). The Td5 was replaced in the Discovery by the AJD-V6 unit in 2004 and the Ford ZSD-424 in the Defender in 2007. Production of the Td5 at Solihull ceased that year making it the last Land Rover-designed-and-built engine.
- Layout: 5-cylinder, in-line
- Block/head: Cast iron/aluminium alloy
- Valves: OHC, chain-driven camshaft
- Capacity: 2,493 cc (152.1 cu in)
- Bore × stroke: 94 mm × 71.1 mm (3.70 in × 2.80 in)
- Compression ratio: 19.5:1
- Fuel injection: Lucas Electronic Unit Injection
- Induction: Allied Signal GT20 turbocharger
- Power: 122 hp (91 kW) @ 4,850 rpm (Defender version)
- 136 hp (101 kW) @ 5,000 rpm (Discovery version)
- Torque: 221 lbf·ft (300 N·m) @ 1,950 rpm
- Production: 1998–2007
- Used in: Land Rover Defender and Land Rover Discovery.