Emira — the four with more

0 0 July 20, 2023 Edit this post

Normally we wouldn't too excited about a four cylinder version of any car.

But in the case of the Lotus Emira, the turbocharged 2.0-litre power plant produces almost as much power as its supercharged V6 sibling.

How good's that?

Supplied by technical partner Mercedes-AMG, the all-aluminium, turbocharged 2.0-litre unit is based on the world’s most powerful four-cylinder in series production.

Badged for launch as the Emira First Edition, it has been further developed by Lotus with new intake and exhaust systems, plus a bespoke calibration matched to new transmission shift-mapping.

Developing 268kW of power at 6600 rpm and 430Nm of torque from 3000-5500 rpm, Lotus says the engine is a perfect match to the Emira’s lightweight, strong, stiff, bonded and extruded aluminium chassis structure and aligns to the Lotus ethos of delivering higher performance through light weight.

Character is enhanced by the inherent day-to-day usability and comfort of the smooth and rapid shifting dual-clutch transmission.

It also offers the added advantages of lower fuel consumption and a target CO₂ emissions figure of 208g/km (WLTP).

As the final mainstream combustion engine Lotus two-seater, Emira is the most powerful four-cylinder model from Lotus in a rich bloodline that spans the Elise, Esprit, Europa, Elan and Elite.

And, at 134kW/litre, it also has the highest specific power output in the Emira range.

Like the renowned 298kW/420Nm supercharged V6, the four-cylinder car delivers all the performance and responsiveness that drivers expect – 0-100km/h in just 4.4 seconds and a 290km/h top speed – while bringing its own unique character to the Emira range.

The V6 does it in 4.3 seconds and has the same maximum speed.

Designed solely for high-performance applications, the 1991cc engine features a cylinder block produced using the advanced chill-casting process: compared to conventional sand-casting methods used in high volume applications, this results in a uniform, fine-grained structure which delivers the high strength and durability needed to withstand the high loads generated.

Following motorsport practise, the block is also of closed-deck design for maximum stiffness, and instead of conventional cast iron liners, the cylinder bores use a patented low-friction coating to save weight.

For the optimal balance of high strength and low weight, both the steel crankshaft and aluminium pistons are forged.

The cylinder head features four valves per cylinder and a 200bar direct injection system.

Intake and exhaust cams feature variable valve timing, while on the exhaust side, the valves can be varied between high and low duration.

The piezo injectors deliver fuel into the combustion chamber with very high precision, both in terms of the amount of fuel and the spray pattern, resulting in enhanced combustion with reduced emissions.

For maximum power, the piezo injectors are joined by the port fuel injectors, mounted directly on the intake side of the cylinder head to deliver the correct amount of petrol needed at full load.

The turbocharger is a ‘twin-scroll’ design, meaning the turbine housing is split into two separate ducts, matched to corresponding ducts in the exhaust manifold.

This minimises exhaust gas pulsation interference, helping to improve the efficient exchange of gases in the cylinders. It also ensures that boost pressure builds up more rapidly, and to further enhance responsiveness, the shaft joining the compressor and turbine wheel runs in ultra-low-friction roller bearings.

To manage boost pressure most effectively, the wastegate is electronically controlled.

Sending drive to the rear wheels is Mercedes-AMG’s acclaimed eight-speed dual-clutch transmission (DCT) – a first use of the technology by Lotus and fitted exclusively to the Emira.

Compared to the six-speed manual and automatic transmissions offered on the Emira V6, the DCT offers even quicker gearchanges with no torque interruption during shifting, enhancing efficiency and shift comfort.

Drivers also have the choice of smooth, effortless changes if they leave the car in Drive, or ultra-fast dynamic changes if they control the transmission themselves using the shift lever in the centre console or steering wheel paddles.

Launch control enables the driver to set the car up for optimum acceleration from a standing start by maximising the available traction from the rear wheels and torque from the powertrain.

The Emira’s light, stiff, bonded aluminium Lotus Sports Car Architecture gave the vehicle dynamics engineers the perfect platform from which to develop the car’s ride, handling and steering characteristics, all of which set the class benchmark, as every Lotus sports car should.

The Emira features race-derived, lightweight, forged aluminium double-wishbone suspension all round, which delivers the greatest control of the tyre contact patch throughout the suspension’s full range of travel, contributing to the Emira’s exceptional agility and responsiveness.

Eibach springs and Bilstein high-pressure monotube dampers are meticulously tuned to suit the Emira, and offered with different settings depending on whether the customer chooses the Tour or Sport chassis settings.

Tour is optimised for road use, offering softer springs and dampers, while Sport is track-focused with stiffer springs and dampers, together with increased camber and toe angles to maximise grip.

The anti-roll bar stiffnesses are also bespoke to Emira, and the component on the front axle is now lighter too.

A choice of specially-developed tyres is available on the four-cylinder Emira, which are asymmetrically sized to suit the exacting requirements of steering and traction – 245/35/R20 on the front axle and 295/30/R20 at the rear.

Lotus' Gavan Kershaw said the suspension had been meticulously tuned to deliver the superb body and control that’s a Lotus hallmark without the car ever feeling harsh.

"We’ve calibrated engine and transmission mapping, in tandem with the Drive Modes, to create a refined and relaxed character in Tour, and with incredible launch performance, superb driveability, even quicker throttle response and kickdown in Sport and Track" he said.

"We’ve also taken the opportunity to refine how the powertrain is linked to the traction and stability control systems to deliver the high-performance feel and connection that Lotus drivers expect.”