Thread: TD5 engine - origins?

Cut and pasted from Web Rover.

Hope it helps.


From January 1999, the Land Rover Defender range was fitted as standard for most markets with the new Td5 diesel engine. The Discovery Series II was fitted with the Td5 from launch, also in January 1999.

The five cylinder direct injection turbo diesel intercooled engine was a brand new design, started by Rover Group in 1993 as part of their development of a range of 4, 5, and 6 cylinder diesel engines to meet all Rover and Land Rover diesel engine requirements. This new range of engines was loosely based upon the L-series 4 cylinder engine, at that time used in the Freelander and various Rover cars.

When BMW bought Rover Group in 1994, the 5-cylinder project's continuation was approved, to replace the Tdi in the Discovery and Defender.

The project was already under way before BMW's takeover, and so contrary to popular belief, the Td5 is in fact a Rover design, not a BMW one. Before starting on project 'Storm', as the Td5 was known during development, Rover's engineers undertook a huge review of competitor's engines, designs and manufacturing practices. The lessons learnt were combined with Rover Group's already extensive experience with the 200 and 300 Tdi and the Rover L-series diesel engines.

In Defender specification, the Td5 develops 122 bhp (120 PS, 90 kW) at 4200 rpm, and in the Discovery this is upped to 136 bhp (134 PS, 101 kW) at 4200 rpm by use of a different fuelling map and an electronic wastegate. Along with 300 Nm (221 lb.ft) of torque at 1950 rpm, these relate to a 9% increase in power and 13% more torque than the outgoing 300 Tdi engine. From 2002 the Discovery automatic was uprated to produce 340 Nm (250 lb.ft) of torque at the same engine speed.

The Td5 uses Electronic Unit Injectors to burn exactly the right amount of fuel, which mean that when first released, the emissions are so clean that was no need for a catalytic converter in order to meet emissions regulations (EU2).

With the introduction of EU3 regulations, the engine gained an Exhaust Gas Regulation (EGR) cooler, as well as a catalytic convertor in the exhaust.

The dual chain-driven overhead camshaft pressurises the fuel in the injectors to 1500 bar (22,000 psi) compared to around 600 bar (9,000 psi) in the Tdi, and this is one of the key advantages of using EUI technology, as it provides good emission control due to the very high pressure of fuel injection. The high pressure in the Td5 is possible because each injector has a camshaft driven pump, so there is no problem with containing high pressure fuel in fuel rails.

Injection of the fuel is controlled by the ECU, which controls the fuel spill valve inside the injector, and this allows fuel to be injected into the cylinder.

The oil filtration method has been greatly improved over the 300 Tdi, with a centrifugal particle filter fitted ahead of the normal filter. This means that oil changes are now only required every 12,000 miles (20,000 km), compared to 6,000 miles (10,000 km) for the 300 Tdi and most other competitors.

The Td5 is the first diesel engine in the Defender to be wholly controlled by an engine management (or control) unit (EMU/ECU) - codenamed 'Thunder' and developed in conjunction with Lucas. The ECU regulates fuel delivery by taking into account a number of factors from the engine and the surroundings - such as inlet air pressure and temperature, intake air flow, coolant temperature and the throttle pedal position from the fly-by-wire accelerator.

The ECU also controls the glow-plug timing and is connected to the alarm to form the main part of the immobiliser system. The ECU improves drivability by taking inputs from the clutch, brake and throttle pedal to smooth out gear changes and reduce driveline shunt. With low range selected on the new LT230Q transfer box, the ECU enables Fast Throttle Control (FTC) which widens pedal travel, giving more control over the engine speed in off road and low speed operation.

The cast iron Td5 cylinder block is closely related in both construction and bore/stroke dimensions to that of the Rover L-series diesel engine, on which the Storm project was loosely based.

The engine uses ‘through-bolt’ fixings for the cylinder head, which ensures that each cylinder bores is subjected to the same compression from the head. This allows close tolerances to be used for piston rings due to the bore-to-head stablility, reducing emissions and minimising oil consumption. This is helped by diamond micro-finishing of the cylinder bores, a proven Rover method.

Other features in common with the L-series include vertical box-section channels cast into each side of the block which both stiffen the block and allowing rapid oil return.

To add further strength to the block assembly, the block is stiffened with an aluminium crankcase ladder frame with oil pump and feed galleries, and a cast aluminium sump.

As on the Tdi and L-series, each piston incorporates a re-entrant shaped combustion chamber in the centre of the top face. The carefully developed shape of the chamber provides an efficient fuel/air mixture at the beginning of combustion, and promotes complete combustion of the combustion mixture. On EU3 engines, the piston bowl is offset, and cannot be interchanged with EU2 pistons.

Two compression rings and one oil control ring are fitted to each piston, and the piston skirt is graphite coated. The upper compression ring sits in a nimonic steel insert to withstand the high combustion forces. Piston cooling is assisted by oil galleries inside the piston, fed by oil jets incorporated in the crankcase walls.

The Td5's con-rods use the modern manufacturing technique of forging the rod in one piece, and then fracture-splitting the big end cap from the main part of the rod (a practice used for many years by BMW). This technique produces a strong and accurate fixing between cap and rod.

The small end of the con-rod is tapered, to provide a large bearing area but minimum intrusion into the piston head, to optimise its strength. The con-rods are common with those of the L-series engine, and are thoroughly proven in numerous vehicle programmes as well as recording perfect reliability.

The camshaft, manufactured for Land Rover by BMW, is ground from a forged steel billet and is then case hardened. It has three cam lobes per cylinder, two to operate the valves, one to pressurised the fuel in the EUI. A duplex chain drive from the crankshaft is used for reliability, rather than a toothed belt drive, which gave problems in the 300 Tdi engine.

Following established manufacturing and design practice, the crankshaft is cast in spheroidal graphite (sg) iron, with cold-rolled fillets for high strength and excellent fatigue resistance.

The Td5 (with manual transmission) has a new design dual-mass flywheel, working in a similar manner to a crankshaft damper. The flywheel consists of two individal masses, connected by spring and damper elements. This helps smooth out individual combustion pulses from each cylinder, especially at low engine speeds. Where automatic transmission is fitted (in the Discovery), the flywheel is unnecessary since the torque converter provides this damping effect.

There is loads of info on Web Rover

oil system

Web Rover

cooling

Web Rover

air induction

Web Rover

fuel system

Web Rover

injectors

Web Rover

ancillaries

Web Rover

Cheers
Pete

Perfect, EXACTLY what I was after, ta much!

The ECU was developed in conjunction with Lucas!!!!

Does this explain the multiple and ongoing electrical/electronic problems and failures suffered by writers to this forum?

My experience with British cars and trucks has firmly convinced me that the Poms have absolutely no idea when it comes to designing auto electrics and gearboxes.

of which I think none were related directly to the ECU.....

Just to add that statement is pretty inacurate at best, and thats me being polite.

there are a number of auto electrics companies and gearbox manufacturers in the UK.

Quaife being one, Hewland being another, both at the absoloute top of their game

With regard to auto electrics companies. There are plenty of those aswell.

Motec (part Australian as far as I recall), DTA, etc etc...

Rgds
Peter.

well said psimpson 7 it took me over a year to read this, and it still right. its keeping maintenance , and good operation seems to keep it reliable. (and good luck)