Peugeot 207 RC: In Detail

Press Release

1.6 litre THP 175 bhp engine

Cooperation

The 1.6 litre THP16v 128 kW (5 175 bhp) engine is a new member of the petrol engine family and derives from cooperation between PSA Peugeot Citroën and the BMW Group.

The aim of this association is to develop engines equipped with innovative technologies that offer a high level of performance – and economical fuel consumption – while meeting the cost constraints imposed on the lower and lower to medium segments to which they belong.

To resolve this problem, each partner brought the full weight of its experience and know-how in fields of engine design and the implementation of manufacturing processes. The engines are produced at the PSA Peugeot Citroën plant in Douvrin, France.

Characteristics

This “EP6 DTS� engine is a sporty offshoot of the “EP6 DT�, the dynamic and versatile 1.6 litre THP engine developing 110 kW (5 150 bhp) which appeared in the autumn of 2006 under the bonnet of the 207. They bear a very close resemblance in terms of their mechanical components and hi-tech specification, however engine mapping has been entirely recalibrated for a sportier style, with changes to the turbo housing and its material to allow higher power levels to be obtained.

From the earliest design stages, the engine specification sought to combine a number of objectives:

• to provide power of the highest order, directly comparable to that of the best 2.0 litre engines,
• to obtain high flexibility in use, particularly through a high level of available torque at the very lowest engine speeds,
• to contain fuel consumption and emissions,
• to overcome compactness and weight constraints to facilitate its installation in small vehicles.

The aim is therefore to favour driveability and driving pleasure while optimising running costs.

The technical choice of a 4 cylinder 1.6 litre engine took precedence because small turbo-charged engines with a high fuel rating offer a significant advantage in terms of fuel consumption compared to conventional naturally aspirated engines with a larger capacity. This downsizing strategy is comparable with that applied to the Marque’s HDi diesel engines.

This 1.6 litre THP 4 cylinder engine has a capacity of 1598 cm3 and develops a maximum power of 128 kW (5 175 bhp) at 6000 rpm. It has a sixteen valve cylinder head with dual overhead camshafts.

Particular attention was paid to torque development and response time. As a result, even at 1000 rpm a torque of 153 Nm is available. Its maximum torque of 240 Nm is reached at only 1600 rpm and this value remains unchanged up to 4500 rpm. It is still 204 Nm at 6000 rpm.

However, this maximum torque can be increased further thanks to the overboost function, which temporarily increases the engine’s turbo-charging pressure. It can then attain 260 Nm during intensive use of the accelerator pedal. Overboost is activated in one of the three top gears under full load from low engine speeds up to 5200 rpm.

Several technological innovations made it possible to rise to this technical challenge, in particular:

• direct injection,
• a Twin-Scroll turbocharger,
• a cylinder head timed by two overhead camshafts with continuous variable timing for the intake,
• a piloted oil pump,
• an innovative crankcase.

Direct injection for a high level of performance

Direct injection allows a high fuel rating in tandem with low fuel consumption. It also gives excellent results in terms of emissions.

A high pressure pump with two pistons driven mechanically and mounted at the end of the intake camshaft supplies the injectors via a stainless-steel distribution rail. High pressure injectors spray the fuel directly and laterally into the combustion chamber at a maximum pressure of 120 bar. The blend is distributed evenly in the chamber, meaning combustion is improved and the engine’s overall efficiency is increased. In addition, direct injection helps to reduce the quantity of fuel that has not burned off completely by limiting the proportion of fuel in contact with the walls.

It should be noted that this turbo-charged petrol engine reaches the relatively high rate of compression of 10.5:1.

The Twin-Scroll turbocharger, a first in this category, for maximum responsiveness

As with the 1.6 litre THP developing 110 kW (5 150 bhp), the use of a Twin-Scroll turbocharger is a first at this level of engine capacity and in fact at this level in the range.

As the name “Twin-Scroll� implies, the system groups the cylinder gas ducts in the exhaust manifold and turbocharger in pairs (“twin�). The ducts therefore convey gases from cylinders 1 and 4 as well as 2 and 3. These two columns of pulsing gas are routed through scrolls, and the flows combine in optimal fashion directly in the turbine to give it maximum thrust.

This configuration, which separates exhaust gases as far as the turbine inlet, exploits their dynamic properties to the full.

This gives rise to a remarkable degree of engine responsiveness, since pressure build-up begins from 1000 rpm and attains maximum torque from 1600 rpm. Response time, often criticised on turbo-charged petrol engines, is therefore dramatically reduced. Response time was also carefully analysed in terms of engine mapping to encourage its instantaneous effect.

The flow of exhaust gases accelerates the turbine up to an engine speed of 220,000 rpm. At the same time, it drives the compressor which compresses fresh air. A wastegate operates above a maximum compression load of 0.8 bar.

However, when the overboost is triggered, opening of the wastegate is delayed to attain a pressure of 1 bar momentarily, thereby increasing the maximum torque to 260 Nm.

Due to the increase in power in relation to the 1.6 litre THP 110 kW (5150 bhp) engine, the turbine housing of the KKK turbocharger is made of steel rather than cast iron.

The cylinder head with dual overhead camshafts and variable timing

The cylinder head of this 4-cylinder engine is eq ui pped with two machi ned overhead camshafts, and also hydraulic tappets for automatic take-up of valve clearance. Thanks to the wide angle of these valves, a considerable reduction of friction is possible through the use of roller cam followers for all elements of the manual transmission. Indeed, one of the project’s priorities was to reduce losses through friction in order to reduce fuel consumption.

The weight of the timing was also optimised to facilitate the build up of engine speed. With this in mind, the valve stems have a diameter of only 5 mm.

Continuous variable timing of the intake camshaft (also called VVT, Variable Valve Timing) ensures optimal power and torque, combined with very favourable values for fuel consumption and emissions.

Oil pump with controlled flow to reduce fuel consumption

The pump with toothed pinions, driven by a chain, provides the exact volume of oil necessary under all operating conditions. Thanks to optimised control avoiding unnecessary energy consumption, this controlled-flow pump consumes up to 160 Watts less energy than a conventional pump, while reducing fuel consumption by around 1 % in the European combined cycle. At 6000 rpm, the gain is 1.25 kW.

In addition, because turbocharged engines are subject to high thermal loads, an oil/water heat exchanger incorporated in the oil filter and with the help of a piloted thermostat maintains the oil temperature at a safe level, even under full load.

Furthermore, by heating the oil more quickly, the exchanger shortens the duration of the temperature build-up phase while reducing fuel consumption and, as a result, emissions.

A crankcase with exceptional properties

Construction of the crankcase in aluminium and in two parts – cylinder block and main bearing cap casting – guarantees:

• extreme rigidity thanks to strengthening grooves,
• excellent acoustics, similar to those of a thicker and therefore much heavier cast-iron crankcase.

The crankcase has cast-iron liners inserted at the foundry. The main bearing cap casting is screwed to the cylinder block, enclosing the crankshaft. Due to important physical constraints resulting from torque generated by the presence of the turbocharger, sintered steel inserts are cast in the main bearing cap casting at the level of the crankshaft bearings. In addition, particular attention was paid to reducing friction in the crankshaft.

Lastly, the crankcase is designed to encourage air movements resulting from connecting rod movements in order to minimise pumping losses at high engine speeds.

Easy maintenance

Depending on conditions of use and driving style, the oil change interval will be 30,000 km or 2 years. The spark plugs and the air filter must be changed every 60,000 km. Actuation of the camshafts by means of a chain is not only accurate and reliable, but also maintenance­free for the entire lifetime of the engine, and no servicing operations are required on the valves thanks to their automatic hydraulic take-up.

Gearbox

This version adopts the «BE4/5T» 5-speed manual gearbox. This gearbox is already coupled with a wide range of petrol and diesel engines within the PSA Peugeot Citroën Group.

On this new sporty petrol engine, the gearbox benefits from special gear staging and shorter gear ratios that make the very most of the engine’s superb flexibility. Only first gear is lengthened to obtain «more dynamic» gear changes in corners at reduced speed, such as a hairpin bend, enabling the vehicle to be driven at 66 kph thanks to a maximum engine speed extended to 6800 rpm for the first two gears.

Note also that the clutch has been reinforced to support the temporary torque of 260 Nm when the overboost function is active.

Performance

The sporty temperament of the 207 RC, a direct result of engine technology and the excellence of the chassis, can be seen clearly in the following figures.

For example, with driver only, just 27.8 s are required to cover the 1000 m standing start, while 0 to 100 kph is attained in only 7.1 s, placing it clearly ahead of its forerunner, the 206 RC. Figures for acceleration are equally eloquent: 7.0 s in top gear from 80 to 120 kph (compared to 10.6 s with the 206 RC). Maximum speed, attained in 5th gear, is 220 kph.

Lastly, the technologies used for this engine and their effect on torque availability at low engine speeds limit fuel consumption (7.2 litres in the combined cycle versus 8.6 litres for the 206 RC) and also CO2 emissions (171 g/km versus 204 g/km on the 206).

Adaptations

Here, the rigorous handling of the 207, already widely appreciated by its customers, is at its most dynamic. The RC is based on a chassis that givesall 207s dynamic styling without compromising safety. With this resolutely sporty engine and a number of specific adaptations, the 207 RC offers extremely efficient and stable handling while remaining very easy to drive.

Wheels and suspension

As on all 207s, the wheels and suspension feature a McPherson type front axle. For the RC, the front articulation of the wishbone takes the form of a ball joint, in place of the elastic articulation. The rear articulation, while still elastic, is strengthened. This assembly guarantees perfect road holding by the front wheels for maximum precision under load.

The stiffness of the rear axle deformable crossmember has been increased by nearly 30% compared to the 207 equipped with the 1.6 litre THP 110 kW (5 150 bhp).

Hydraulic dampers with valves set to a pressure of 5 bar are structurally identical to the rest of the range and obey patterns specifically designed for the 207 equipped with this engine. Similarly, the rigidity of the front and rear springs has been increased to make the chassis as efficient as possible in terms of road holding.

Steering

The «brushless» electric power steering, acknowledged since its launch for its versatility, offers good handling at low speed and precision at high speed and is recalibrated on this version to take account of engine performance and to offer maximum feedback of information for maximum precision while driving.

Brakes

Braking is assured at the front by special ventilated discs with a diameter of 302 mm and a thickness of 26 mm. The diameter of the brake calipers on these discs has been increased to 57 mm. 249 x 9 mm non-ventilated discs are used at the rear.

A Teves Mk60 ESP (Electronic Stability Program) system is featured on this version as standard. It includes ABS, electronic brake force distribution (EBFD), emergency brake assist (EBA), traction control (ASR) and stability control (CDS), which detects any incipient understeer or oversteer. Lastly, it allows the integration of an all-new system, the SSP (see section on Safety). The ESP and its functions (AFU, ASR, CDS) are fully disconnectable, to allow demanding and experienced customers to exploit the capacities of the 207 RC to the full.

Tyres

The 207 RC is fitted exclusively with new «Pitlane» 17 inch alloy wheels with 9 spokes, exhibited at the 2006 Paris Motor Show on the 207 concept car. They are clad with Bridgestone Potenza RE050A 205/45 R17 W tyres.