23-08-2006
The Lotus Exige 265E – the most powerful road version of the Lotus Exige ever – and it
runs on environmentally friendly Bio Fuel!
Lotus Engineering, the engineering consultancy division of Group Lotus Plc has developed a
bio-ethanol E85 version of the Lotus Exige.
The research vehicle is a true Lotus (it weighs just 930 kg unladen) and is called the Lotus
Exige 265E. 265 indicates the approximate horsepower and is consistent with the naming
strategy of other one-off and limited run Lotus variants such as the Lotus Sport Exige 240R; the
E indicates the environmentally favourable bio-ethanol E85 fuel (85% ethanol alcohol and 15%
petrol / gasoline) that powers this extremely high performing sportscar.
Key to this performance is a slightly modified version of the 2ZZ VVTL-i supercharged and
intercooled high revving 4-cylinder engine from the standard Lotus Exige S. This now gives an
estimated set of performance figures that would thrash the majority of “Super-Unleaded”
performance cars: 0-60 mph in 3.88 seconds, 0-100 mph in 9.2 seconds and a top speed of 158
mph! In fact, the Lotus Exige 265E is probably the world’s quickest road-legal E85 bio-ethanol
car.
Key changes have been made to the fuel system, the engine calibration and the four fuel
injectors mounted on the inlet manifold have been enlarged. Two additional fuel injectors have
been fitted at the supercharger inlet to increase the amount of fuel being injected in to the
engine under higher engine loads and to further cool the charge air prior to combustion.
What is Bio Ethanol E85?
Bio-ethanol E85 is a fuel which is a mixture of 85% ethanol (an alcohol) and 15% petrol /
gasoline. The bio-ethanol can be made from bio-mass plant crops such as cereals, sugar beet,
sugar cane and wood. As these plant crops grow, they absorb carbon dioxide from the
atmosphere, which then partly offsets the carbon dioxide (CO2) emissions produced during the
burning of the bio-ethanol fuel in the car’s engine.
Why Bio-Ethanol?
Different bio-fuels were considered for this research project, bio-methanol, bio-ethanol and biobutanol.
E85 bio-ethanol was the finally chosen as the fuel as its characteristics allowed the
engineering project team to enhance the engine performance. The fact that this vehicle uses a
pressure charged engine provided even more opportunity to exploit the performance
characteristics of a high-octane fuel. Ethanol has a high octane rating, which allows an optimum
timing for engine ignition and has a fast flame speed in the cylinder, so the fuel burns faster,
increasing the efficiency of the engine.
The Benefits of Bio-Ethanol
The beauty of ethanol is its ability to produce more power in the engine than with conventional
petrol / gasoline fuel. The Lotus Exige 265E now produces 264 hp (197 kW, 268 PS) at 8000
rpm, and 184 lbft (249 Nm) of torque (at 5500 rpm), up by 46 hp (34 kW, 47 PS) or 21% and 25
lbft (34 Nm) or 16% over the standard petrol / gasoline Exige S. With the total weight of
approximately 930 kg (unladen), the power to weight is approximately 283 hp / tonne (211 kW /
tonne, 287 PS / tonne).
Ethanol has less stored energy per unit volume than gasoline so the fuel economy is less,
however as E85 ethanol is 85% sourced from renewable bio matter, there is a net reduction in
carbon dioxide (CO2)
Geraint Castleton-White, Head of Powertrain for Lotus Engineering explains the rationale
behind the Lotus Exige 265E technical demonstrator: “We wanted to prove the point that green
sportscars can also be very high performing sportscars. The fact that we have produced a
research version of the Exige that is more powerful than the standard road car is a testament to
the benefits of going green. We are also pleased that this vehicle demonstrates our engineering
capabilities, our understanding of flex fuel vehicles and our knowledge of emerging fuel
technologies. It also promotes bio-ethanol as a fuel of choice for the enthusiastic driver as well
as the environmentally conscious driver.
Mike Kimberley, Chief Executive of Group Lotus explains the Lotus ‘Green Strategy’: ”Lotus
Engineering is actively pursuing technologies that will improve the efficiency and environmentally friendliness of engines in the future. Carbon dioxide reduction is a priority, as is
anything that can reduce our reliance on fossil fuels. We are one of the world leaders in
powertrain engineering especially in the internal combustion sector and we are researching into
all areas of alternative and conventional fuels to get greater efficiencies, power, performance
and reduce net emissions and Bio Ethanol research is one area where we are expert. The
problems that are facing the automotive industry at the moment are challenging, and these
solutions fit with the Lotus culture and expertise.”
Mike Kimberley continues: “We have decided to develop a thorough understanding of the
techniques and technologies of what alternative fuels can achieve, to produce vehicles that are
both fun to drive and environmentally friendly. We are also working, globally, on hybrid and
electric vehicles together with governments and universities and as an engineering organisation
we have a duty and a desire to promote these ideas to a worldwide customer base.”
Rapid Project Delivery for a Rapid Car!
The final sign-off test drive was completed just 5 weeks after the project was instigated and has
resulted in a demonstration vehicle that not only excites the driver but also is at the forefront of
environmentally friendly vehicles.
Looking to the Future:
The next phase for the vehicle is to upgrade the calibration to a flex fuel spec to allow use with
initially gasoline, followed by the possibility of a multi fuel flex calibration to use fuels such as
bio-methanol and bio-butanol in addition to the conventional gasoline / petrol and bio-ethanol.
The Lotus Exige 265E is purely a research vehicle for Lotus Engineering and Lotus does not
intend to put the car into production or sell aftermarket kits for Lotus Cars.
The Lotus Exige 265E in more detail.
The Lotus philosophy is all about performance through light weight. The Exige 265E is built to
the lightest specification possible without resorting to expensive and rare materials normally
found in the rarefied environment of Formula One or Aerospace Industries where weight
reduction is often considered more important than cost. The performance improvements of using bio ethanol have been made through increasing the power of the engine without
increasing the weight of the engine and therefore the overall weight of the car.
The Engine
The heart of the Exige 265E is a Roots-type supercharger (with a sealed-for-life internal
mechanism meaning that it does not require the use of the engine’s oil) and air to air intercooler
attached to the tried and tested 4-cylinder, 1.8 litre 2ZZ-GE VVTL-i engine. Using a
development of the supercharger and intercooler package from the Exige S, the Exige 265R
has peak power of 264 hp (197 kW, 268 PS) at 8000 rpm, 184 lbft (249 Nm) of torque (at 5500
rpm) up by 46 hp (34 kW, 47 PS) or 21% and 25 lbft (34 Nm) or 16% over the standard gasoline
Exige S. Maximum engine speed is 8000 rpm (8500 rpm transient for up to 2 seconds).
Ethanol produces more power in the engine than with conventional petrol / gasoline fuel. This is
due, in part, to the additional oxygen atom attached to the ethanol alcohol molecule so helping
the combustion process in the cylinder to burn more effectively, efficiently and with more power.
The roof scoop ensures that the air-to-air intercooler works as efficiently and effectively as
possible in all climates and environments. All charge air ducting has been kept as short as
possible with large diameter pipes making sure that the bends in these ducts are not too tight, to
the benefit of throttle response and efficiency. The Roots-type Eaton M62 supercharger is run
from the crankshaft, and has an integral bypass valve for part load operation.
A “Stage One” sports exhaust exits from the centre of the undertray.
The 2ZZ VVTL-i engine has two cam profiles – a high speed cam and a low speed cam. The
seamless switch point between these two cams is completely variable depending upon driving
conditions and engine load, and the driver will not know which cam is being used at any point.
This gives the Lotus Exige 265E a smooth and linear surge of power from idle speeds all the
way to the maximum 8500 rpm.
An electronic drive-by-wire throttle ensures the quickest engine response possible whilst
keeping the emissions as clean and as low as possible, to meet relevant legislative demands.
Four enlarged fuel injectors have been fitted to increase fuel flow into the engine under normal
operating conditions. Two additional fuel injectors have been fitted at the supercharger inlet to
increase the amount of fuel being injected into the engine under higher engine speeds and
loads. This has also enabled the engineering project team to take advantage of ethanol’s higher cooling effect to further cool the charge air prior to combustion, which in turn reduces the
amount of power required to operate the supercharger. A true Lotus solution where the ethanol does more than just provide energy for combustion!
Extra Functions for the Lotus T4e Engine Management System.
The Lotus T4e Engine Management system is used in the Lotus Exige 265E. This engine
management system has been programmed to optimise the ethanol in the supercharged and
intercooled engine.
The lightweight C64 six-speed gearbox is fitted with the closest ratios and gearset afforded by
the transmission. The gearbox offers a fast, precise and light gearshift, ensuring drivers have
total control and flexibility to apply the power exactly as and when required.
Aerodynamics is the key
The Lotus Exige 265E uses the same aerodynamic package as the production Exige. Like all
Lotus cars, the Lotus Exige 265E isn’t all about straight-line performance.
The Lotus Exige 265E is probably the world’s quickest road-legal E85 bio-ethanol car. Not only
is the engine important to the performance but also so is the aerodynamic package, which
creates 41.2 kg (90.64 lbs) of downforce - 19.3 kg (42.46 lbs) at the front and 21.9 kg (48.18
lbs) at the rear - at 160 km/h (100 mph). This downforce ratio between front (47%) and rear
(53%) is balanced and remains constant at the speeds of which the Exige 265E is capable.
The Legendary Chassis and Body
The Lotus Exige 265E is built around the revolutionary and award winning extruded and bonded
aluminium tub, with a light weight steel rear subframe, as used in the Exige. The chassis tub
itself weighs just 68 kg (150 lbs) and has a torsional stiffness of 10,500 Nm per degree.
The body of the Lotus Exige 265E remains unchanged from the Exige as it is already a winning
formula that is both effective and stunning to look at.
To further differentiate the Lotus Exige 265E from its production cousins, two bold stripes (in
yellow to symbolise the bio-ethanol fuel and green to demonstrate the environmental
considerations of the vehicle).
Exterior
Lightweight Lotus Sport five spoke forged alloy wheels have a slightly wider section, when
compared to the standard Exige wheel, to accommodate the optional extra track use only
specification slick tyres. These wheels, with Lotus Sport etched on one spoke of each wheel,
are painted in “High Power Silver” colour.
The Brakes and the Suspension
The brake system has been upgraded to 4-piston AP Racing calipers with sport brake pads and
increased diameter 310 mm drilled and vented discs at the front. Brembo single-piston sliding
rear calipers with 282 mm diameter discs are fitted at the rear. High grade silicon brake fluid,
metal braided brake hoses are all linked to the proven Lotus track tuned servo-assisted fourchannel
ABS system that enhances braking performance and minimising stopping distance
without taking over from the skill of the driver.
To suit different driving styles and road conditions, the Lotus Exige 265E has been fitted with
Ohlins two-way adjustable dampers and ride height adjustment to reduce the ride height from
130 mm to 120 mm and an adjustable front anti-roll bar.
An oil “Accusump” is included as an oil reservoir backup for extreme track use. Cornering
speeds and the lateral forces generated within the car when driven on the track are far higher
than what can be experienced safely on the road and the “Accusump” ensures that, under these
extreme conditions, the engine oil pressure remains constant.
A “Stage One” sports exhaust is fitted with the bifurcated exhaust pipes exiting from the centre
of the anodised-finish 3-piece rear diffuser. Front driving lamps, twin oil coolers, central door
locking, alarm (with immobiliser) and air conditioning (weighing in at a minimal 15 kg, 33 lbs)
completes the equipment package.
Interior
The unique interior trim takes the black, green and the yellow theme of the exterior paint colours
by using predominantly black trim with green and yellow highlights on certain components
including the padded leather door inserts and the seats.
Text and photos courtesy of Lotuscars
