Published on July 29th, 2014 | by Daniel Sherman Fernandez0
Land Rover Discovery Diesel Power Admired
The Discovery comes equipped with an impressive diesel engine that you might not have realized. At the heart of the improvements introduced with Land Rover Discovery 4 for 2014 is an exceptional and highly efficient new diesel engine. The LR-TDV6 3.0 sequential turbodiesel is based on the existing LR-TDV6 2.7-litre engine, but radically redesigned to deliver substantially higher performance, lower emissions and better fuel economy.
The 2.7-litre has won many admirers as one of the most refined diesels ever made. The new, twin turbocharger LR-TDV6 3.0 boasts substantial increases in both power – up 29 percent to 245PS and torque, up 36 percent to 600Nm. The ability to deliver maximum torque at just 2,000rpm, combined with unparalleled throttle response, substantially enhances the Discovery’s already acclaimed ability both on and off-road.
The new 3.0-litre diesel can significantly out perform its rivals by delivering 500Nm in only 500 milliseconds from idle. From the driver’s perspective this means instantaneous access to 83 percent of maximum torque.
But despite this extra performance, engine emissions are dramatically reduced. When fitted with DPF, the new LR-TDV6 3.0 meets EU5 emissions requirements (not due to come into force until 2011) and with a CO2 figure of 244g/km, it undercuts the existing 2.7-litre automatic by ten percent. Fuel economy is also improved by 9 percent, delivering 30.4mpg (9.3 l/100km) on the EU Combined cycle.
The new 3.0-litre engine has been developed by a joint Jaguar Land Rover team, with base characteristics designed from the outset with the requirements of both brands in mind. High levels of torque and fast response from low revs perfectly suits both Jaguar and Land Rover DNA. The Jaguar version, the AJ-V6D Gen III S, was recently launched in the new XF sedan.
The LR-TDV6 engine has a deeper sump than its Jaguar sibling, to ensure the efficiency of the lubrication system is not compromised when venturing off-road. The oil scavenge system of the turbochargers has been enhanced for a similar reason, ensuring no oil collects in the turbochargers at extreme angles in off-road conditions.
For the Land Rover version, belt drives are waterproofed, as are the alternator, air conditioning compressor, power steering pump and starter motor. The engine is also tuned specifically to allow for the greater demands made on the Land Rover Discovery 4, particularly for towing and all-terrain driving.
Twin-turbos – immensely efficient, highly responsive
A key feature of the new LR-TDV6 3.0 is the unique, parallel sequential turbocharger system, the first of its type to be fitted to a V-engine anywhere in the world. Delivering high torque throughout the entire engine-rev range, improved throttle response and low CO2 emissions, the twin-turbochargers work sequentially to provide unrivalled response and best-in-class torque at low engine speeds, while also packing a huge punch at higher speeds.
Driving a turbocharger requires pressure from the exhaust, creating pumping losses in the engine and increasing fuel consumption. Under the control of the engine management system, valves isolate the secondary turbocharger both from the exhaust stream and the engine inlet tract when it is not required. A balance pipe connecting the two manifolds allows the gas from both manifolds to feed through the primary turbocharger.
The new 3.0-litre diesel can significantly out perform its rivals by delivering 500Nm in only 500 milliseconds from idle, unlike many diesels which can suffer turbo-lag at very low revs. From the driver’s perspective this means instantaneous access to 84 percent of maximum torque.
Third generation common rail
A new common rail fuel-injection system delivers up to five injections on each cycle at a pressure of 2000bar. Each injector tip is perforated by seven holes through which finely atomised fuel is sprayed into the cylinders. The high-pressure injection increases power, improves economy and reduces both CO2 and particulate emissions. New, high-speed piezo injectors are designed to keep injection noise to a minimum.
Piezo crystal ‘packs’ operate each injector by expanding when an electric current is passed through them. They react virtually instantaneously but make a distinctive click when fired, which can add to diesel engine noise at idle. The crystals in Land Rover’s new injectors are fitted nearer the tip meaning they are mounted deeper inside the engine providing better sound insulation and quieter operation.
Also new to the third-generation fuel-injection system is ‘metering mode’. Traditional diesel common rail fuel pumps oversupply the injectors, with the surplus being returned to the fuel tank. During this process, fuel temperature increases and cooling it again consumes considerable amounts of energy. In metering mode, the pump delivers fuel to the injectors only at the rate required. Consequentially, there is no rise in fuel temperature and no wasted energy.
Rugged yet lightweight
The two cylinder heads, with four valves per cylinder, are made from aluminium and the cylinder block is made from compact graphite iron (CGI) as before. The higher tensile strength of CGI makes it possible to cast a smaller block some 80mm shorter than a conventional ‘grey’ cast iron equivalent.
The new, water-cooled, exhaust gas recirculation system (EGR), important for reducing pumping losses and emissions of NOX in a diesel engine, is more efficient and consumes less power than its predecessor, with the valves allowing exhaust gas into the system being located on the ‘hot side’ of the engine nearest the exhaust manifolds. These valves never cool while the engine is running, so there is no condensation of combustion deposits which occurs on engines fitted with ‘cold side’ valves, hence the EGR system always works at maximum efficiency. Since the EGR cooling is so effective, exhaust gasses can bypass the system and return to the exhaust pipes, allowing faster engine warm-up from start-up and reducing emissions still further.
EU 5 emissions regulations have been achieved using conventional diesel oxidation catalysts and diesel particulate filters (DPFs). NOX levels are reduced sufficiently at source through the combustion system design, the addition of the new common rail injection system and the new EGR system with by-pass. As a result, specialised NOX exhaust after-treatment is unnecessary, avoiding a potential cost and the need to use additional precious metals in the exhaust system.
The CGI cylinder block and new piezo injector design reduce combustion noise in the new engine. Multiple, precise injections of fuel on the combustion stroke also reduce combustion noise and all engine covers including camshaft covers, front covers and the sump have been optimised to subdue radiated noise.
The new diesel underwent analysis using the latest computer aided engineering techniques, followed by exhaustive rig testing. All the engine enclosures have been ribbed to minimise radiated noise.
Internal friction, a major contributor to unnecessary fuel consumption, has been addressed by careful optimisation of the crankshaft, valves and pistons. All these features combine to make the new LR-TDV6 3.0 Sequential Turbo Diesel one of the quietest premium diesels on the market today with increased service intervals of 16,000 miles.
Levels of refinement on the new LR-TDV6 engine are such that Land Rover’s patented device for the diesel fuel filler neck, to reduce the risk of inadvertent fuelling with petrol, is fitted to the new Land Rover Discovery 4.
Responsive new transmission
The LR-TDV6 3.0 is mated to the revised and super-smooth ZF HP28 6-speed automatic transmission. Its characteristics have been optimised by Land Rover engineers to provide class-leading response, with rapid and refined shifts. The dramatic enhancement of both power and torque low down the rev range on the new engine have made it possible to actuate the transmission’s lock-up clutches much earlier in each gear, reducing slip through the hydraulic torque converter, so helping with the improvements in both fuel consumption and CO2 emissions.
Discovery Diesel Technical Specifications
- Engine type: 3.0L SDV6 Diesel
- Power: 256 PS @ 4000 rpm
- Torque: 600 Nm @ 2000 rpm
- 0-60 mph: 8.8 s
- Max speed:180 km/h
- CO2: 213 g/km
- Combined fuel consumption: 35.3 MPG (8.0 l/100km)
- Kerb weight: 2570 kg