08
September
2014
|
18:00
Europe/Amsterdam

2014 lexus rc f: lexus' most powerful v8 engine

 

OUTLINE

 

The new RC F coupe has Lexus' most powerful V8 engine, with 12% more power than the IS F engine on which it is based.

 

All-new cylinder heads and lighter moving parts have increased the maximum power of the 5.0-litre 32-valve engine by 54PS (40kW) to 477PS (351kW), with maximum revolutions increased from 6800 to 7300rpm.

The compression ratio has been raised to 12.3:1, to boost torque across the entire revolution range. The engine and transmission cooling systems have been improved, to increase track-day suitability.

The new engine is matched to an evolved 8-speed Sports Direct Shift (SPDS) transmission, with a more linear response to accelerator-pedal operation.

Uniquely for a Lexus performance engine, the new 2UR-GSE engine adopts the Atkinson cycle when operating at cruising speeds, to deliver enhanced fuel economy.

HIGH PERFORMANCE AND FUEL EFFICIENCY

In cruising condition, fuel economy of the RC F is comparable to a 4.2-litre engine at maximum.

 

The use of the Atkinson cycle is just one of a number of strategies to optimise fuel economy and achieve Euro 6/LEV3-ULEV70 emission compliance.

In the Atkinson cycle, the inlet valves are held open longer than normal to allow a reverse flow of intake air into the intake manifold, thereby decreasing pumping loss and increasing thermal efficiency.

The Lexus VVT-iE (Variable Valve Timing-intelligent Electric motor) technology has been redesigned to extend the range of inlet camshaft timing adjustment for the Atkinson cycle. The Otto cycle is used to achieve RC F's impressive performance levels.

The stoichiometric air/fuel ratio range has been expanded to 220km/h, for a substantial increase in practical fuel economy during performance and high speed driving.

The new engine was designed to provide instantaneous torque, as in the Lexus LFA, whereby the driver can feel torque output increasing during acceleration.

Special features of the RC F engine also include titanium valves, forged connecting rods, an optimised exhaust layout to more effectively harness exhaust pulses and an air-cooled oil cooler for optimum durability. Internal engine parts have been redesigned to reduce reciprocating and hence increase engine response and revolutions.

The majority of the engine parts are new, including the intake manifold and throttle body, intake and exhaust valve train, motor-driven VVT, cylinder head and cylinder-head cover, Lexus D-4S dual injection system, spark plugs, piston and piston rings, connecting rod, crankshaft, crank main bearing and cap, exhaust manifold and heat insulator, oil pan and baffle plate, alternator clutch system, and engine and transmission oil coolers.

The 2UR-GSE engine's breathing has been improved thanks to new cylinder heads with improved porting and a high-flow/high tumble ratio. In addition, intake surge-tank capacity has been optimised, as have the intake manifold length and diameter.

The throttle diameter has been increased from 76 to 83mm. New four-into-two exhaust headers reduce interference and hence further improve engine breathing.

A new intake camshaft profile increases valve lift and suits the Atkinson cycle, while improvements to the electronic VVT-i system have expanded its range of operation for increased fuel economy and performance.

The exhaust system features large diameter front pipes to minimise back pressure and ensure high power output. The merged areas of the exhaust pipes have been enlarged to achieve a clearer engine sound.

Additionally the structure of the main muffler has been optimised to achieve both quietness at low rpms and dynamic volume at mid-to-high rpms.

The Lexus D-4S dual-injection system has been redesigned, with higher injection pressure of 18Mpa and improved fuel atomisation shape, to optimise power and fuel economy while minimising emissions. RC F has a lot of fuel-saving measures, from its aerodynamic body and dual VVT-i equipped engine to its highly efficient eight-speed transmission.

The engine design also includes measures to raise engine revolutions, including titanium inlet and exhaust valves, new high-strength forged connecting rods and new main-bearing materials. Crank pin diameter, connecting rods big-end bearing size and crank counter-weight size have all been reduced, to lower reciprocating weight.

A revised oil pan baffle shape has reduced agitation and hence friction, while new air-to-oil coolers for the engine oil and transmission fluid increase circuit driveability. As a final touch, the new 2UR-GSE engine has a one-way clutch on the alternator pulley.

8-SPEED SPDS TRANSMISSION

The RC F coupe has an improved 8-speed Sports Direct Shift (SPDS) transmission. The transmission control program has been refined, to suit the higher engine speeds of RC F's new engine and deliver a more linear response to accelerator pedal action and hence a more dynamic feeling to driving the new sports coupe.

 

The transmission provides a balance of linear acceleration, optimum fuel economy and driveability under all conditions, and smooth shift feel.

It has five driver-selectable modes — ECO, NORMAL, SPORT S, SPORT S+, and M mode, which has full torque-converter lock-up from second to eighth gears for 'clutchless' manual shifting.

Up changes are made in just 0.1 of a second at minimum case in M Mode, with the transmission's throttle blipping control matching the engine speed to the gear.

The transmission SPORT S mode includes G-sensor AI-Shift control, which uses information from the vehicle's G-sensors on driving status to provide the optimal gear ratio for sporty driving. In SPORT S mode, the transmission offers more dynamic acceleration control and hence a more sporting driving experience.

In addition to performing quicker downshifts than SPORT S mode, by holding the engine at a higher speed, SPORT S+ mode helps to achieve dynamic driving under high load conditions such as when driving on the race circuit.

The transmission will automatically downshift during hard braking for a corner, hold a lower gear through the corner for greater control, and then give the driver a greater power response on corner exit by selecting a suitable low gear.

NORMAL mode provides the fuel economy and seamless acceleration traditionally associated with a Lexus electronically-controlled transmission. It uses the eight ratios for optimum fuel economy, while coordinating control with the throttle to provide smooth acceleration with minimum feeling of gear changes.