Rover Introduce A New Tax Beating Turbo-Charged 1.8-Litre Engine For The Successful 75
Published: 17th July 2002
The new 1.8T models are available on Rover 75 Saloon and Tourer body styles with a range of trim specifications available from Classic to Connoisseur SE.
This addition to the engine range complements the 1.8, 2.0 V6, 2.5 V6 and the accomplished 2.0-litre common rail turbo-diesel – each offering class-leading refinement.
The Rover 75 1.8-litre turbo-charged 4-cylinder engine holds many advantages over the competition. Weighing in at just 100kg, the K Series’ lightweight construction provides exceptional levels of responsiveness and drive.
Available in showrooms from early August, the new 1.8T Saloon models will be priced from £18,295 for the Classic specification to the Connoisseur SE at £22,120.
Rover 75 1.8T – Power Unit in Detail
Rover engineers have tapped into previously hidden development potential to produce a new 150Ps turbo-charged version of the K Series 1.8-litre engine which makes its debut in new versions of the award winning Rover 75 range. The Rover 75 1.8T models have been developed specifically to meet the growing demand for compact-executive cars that combine tax-efficient CO2 ratings (and the associated good fuel economy) with excellent performance and driveability.
The new 1.8T versions have a tax-beating CO2 rating of 193g/km, thus reducing the 2002/03 UK company car tax liability to 20% of list price plus lower running costs through enhanced fuel economy.
At the same time, the 1.8T performs well with good acceleration. 60mph passes from a standstill in 9.1 seconds and in gear performance in fourth gear between 30-50mph and 50-70mph in fourth gear can be achieved in 7.1 and 7.4 seconds, respectively. This ‘have your cake and eat it’ result follows a very intensive and carefully-judged engineering programme to produce the first ever turbo-charged production version of the lightweight K Series engine.
Background and Programme
For the ultimate in thermodynamic efficiency with low emissions, it was decided to apply the latest turbo-charging technology to the 1.8-litre, 4-cylinder K Series engine, which offered an excellent starting point of high efficiency and very low weight.
Packaging and pre-prototype engineering of the turbo-charger, intercooler and ducting installation was carried out swiftly and accurately via MG Rover Group’s advanced Electronic Product Definition (EPD) facility. The Rover 75 was one of the very first cars in the world to have been entirely designed on this type of dynamic real-time system, as there was already a fully digitalised ‘model’ of the Rover 75 from which to begin work.
The powerful ‘Virtual Engineering’ technology makes it possible
to carry out analysis of the vehicle assembly process (via ‘E-build’)
and dealer servicing operations months before a physical prototype exists.
This reduces the traditional time-consuming development of the first prototypes,
which were therefore close to optimum before physical testing began. Adding
speed and efficiency to the programme were the company’s rapid prototyping
facilities, such as laser-cured resin
modelling machines. Engine performance and economy was also fully simulated
to optimise inlet, exhaust and turbo-charger geometry and performance,
before committing to the manufacture of production tooling.
Once prototypes were built, MG Rover engineers had the pick of the world’s automotive testing facilities to assess the performance and reliability of the new Rover 75 1.8T. Hot climate work was carried out in Australia and USA, with the opposite extremes being covered in Canada. Specific engineering tests were completed using carefully selected chambers and test tracks in several more countries.
Under the Bonnet of the Rover 75 1.8T
For many years, turbo-charged petrol engines have tended to be compromised by the fact that turbo-charger design has inevitably been skewed in favour of the far more common diesel applications. Turbo-chargers designed mainly for the narrower and lower speed bands of diesels were difficult to optimise for petrol engine use, giving less satisfactory results either at low speed or at high speed, according to the size of turbo-charger chosen.
The Rover 75 1.8T, however, takes advantage of Garrett’s latest technology, using their new T100 turbine wheel design in a GT20 turbo-charger. Specifically designed to suit modern petrol engine characteristics, the T100 design contributes to the excellent driveability of the 1.8T under all speed and load conditions.
Associated with the turbo-charger installation are a number of important engineering changes. A special exhaust manifold in cast stainless steel can reliably withstand temperatures in the region of 1000 °C. Uprated pistons and connecting rods are
fitted, with the piston configured to give a 9.2:1 compression ratio. An uprated oil pump provides a 12% higher oil flow rate to meet the turbine bearing lubrication requirements, while the modified main bearing ladder casting has an inlet for oil return from the turbo-charger.
The throttle body is of course sealed to retain turbo-charger boost pressure, with a suitably revised manifold pressure sensor, and the fuel system modified, with a returnless feed controlled by a pressure demand regulator, plus new fuel injectors with higher maximum flow rates. Modifications to meet the extra cooling airflow demands of the engine and intercooler include a revised undertray for the engine compartment.
The philosophy behind the 1.8T was to use moderate boost pressure, so that the compression ratio could be kept fairly high, (at 9.2:1, compared with 10.5:1 on the normal 1.8 engine), for maximum efficiency at lower engine speeds when running off-boost. Emphasis has also been placed on providing strong and even torque throughout the normal driving range - the curve is virtually flat between 2100rpm and 4000rpm with 215Nm(159lbs ft) developed throughout.
Such torque allows the 1.8T to easily pull higher gearing, using the
3.9:1 final drive of the 2.5-litre models in place of the 4.4:1 unit used
for the regular 1.8- and 2.0-litre versions. As a result, the 1.8T has
vigorous in-gear acceleration, achieving
30-50mph in fourth gear in 7.1 seconds.
Through the gears, the 1.8T leads the competition with a 0-60mph dash achieved in 9.1 seconds. Despite the brisk performance, the efficiency and high gearing of the 1.8T allows enhanced economy, with an official Combined figure of 35.3mpg and Extra Urban of 46.3mpg again leading the class.
On the road, the 1.8T engine refinement and response characteristics harmonise well with the Rover 75 chassis, making the car well balanced and enjoyable to drive at any speed.
Model Availability and Specifications
The new 1.8T power unit is available from launch with a 5-speed manual
transmission in both Saloon and Tourer body styles. A 5-speed automatic
transmission will be made available with the 1.8T engine later in 2002.
