Chassis and suspension systems
The Lotus Sport Exige is directly developed from the road-going Lotus Exige that was unveiled at the Geneva
Motorshow in 2004. The heart of the Sport Exige is the bonded and extruded Aluminium Chassis, the technology for
which was first introduced in the Lotus Elise in 1995.
The Exige chassis, which is also used in the Lotus Elise 111R, is the latest development of this award winning
structure and weighs 68kg and has a torsional stiffness of 10500 Nm/degree. Made up of 25 separate extrusions,
and bonded with an epoxy adhesive, the chassis in the Lotus Sport Exige is an exceptionally stiff, strong and
lightweight structure. This Lotus technology is so world-leading that it has been used on other non- Lotus
products including high performance production front-engined V12 and V8 GT cars.
An FIA approved 8-point roll cage has been bolted to the chassis, prior to the bodywork being fitted.
Double wishbone front suspension is mounted to the same suspension hard points as the road-going Lotus Exige,
whilst the rear suspension picks up to a revised rear subframe. However, being a full racecar, there is adjustment
for ride height, camber and castor, as well as adjustable front and rear anti-roll bars. Coil springs are mounted
over Ohlins ST44 3-way adjustable dampers front and rear.
The Body
Lightweight "Z-Preg." carbon fibre bodywork was specially manufactured for Lotus by RTN, the team responsible
for the Le Mans winning Bentley. These panels (front clam, "A" panel, body side and sill, roof, engine cover and
rear clam) have been made using an innovative low temperature curing process. The moulds were taken directly from
the Sport Exige styling "clay" and the resulting carbon fibre panels are race-ready without having to rely on the
costly tooling process used in current carbon fibre technology. This is thought to be the first time that this
technology has been used on such large carbon fibre panels.
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An aerodynamically developed front splitter, carbon fibre rear diffuser and an adjustable carbon rear wing
provide increased levels of downforce. The interior of the Lotus Sport Exige is similar to the standard Exige, but
the standard roadcar wiring harness is replaced with a full Raychem 25 system incorporating Mil-spec connectors
from Beru Formula 1 Harnesses. Conventional fuses are replaced with circuit breakers, and a Stack display with
integrated data recording is fitted as standard.
A racing bucket seat (driver side only) is mounted as right hand drive to optimise weight balance through right
hand corners (most circuits run clockwise). A six-point seat belt, prepared for using HANS Safety System, and a
removable steering wheel (with quick-connect coupling) is included in the interior package.
The composite energy absorbing crash structure used on the standard road cars is also carried over to the
Lotus Sport Exige. This glass fibre composite structure, around five times more energy absorbing than the
equivalent steel component, also houses the larger water radiator and provides efficient cooling and air ducting
over the carbon front clamshell. A 100 litre FT3 safety fuel cell (with quick refuelling system) is mounted
behind the driver and in front of the engine (as with the road-going Exige). A fully plumbed in electrical fire
extinguishing system completes the body package.
Brakes
AP Racing provides the non-ABS braking system, which includes the pedal box (with brake balance bar and
cylinders). AP Racing also provides the powerful six piston brake calipers at the front and four piston brake
calipers at the rear. These calipers are mated to vented discs (344 mm diameter at the front and 330 mm diameter
at the rear).
Rims and Tyres
Ultra lightweight OZ Racing Chrono single-piece cast magnesium rims (8.8J x 17 ET40 at the front and 11.25J x
18 ET50 at the rear) are shod with Yokohama tyres (250/610-17 at the front and 280/650-18 at the rear).
Powertrain: Engine and Transmission
A narrow angle V6, 2,998 cc Swindon Racing Engines tuned GM racing engine is mounted longitudinally in the
Lotus Sport Exige. The naturally aspirated 32-valve engine produces 400 hp (296 kW or 405 PS) at 7,750 rpm and
294 lb.ft (398 Nm or 40.6 kgm) of torque at 6,500 rpm and has a maximum engine speed of 8,250 rpm. When the
light weight of the Lotus Sport Exige is taken into consideration, the power to weight ratio is a phenomenal
470 hp / tonne (0.351 kW/kg or 476 PS/tonne). The engine itself weighs 157 kg.
Breathing is via an F1-style airbox and air snorkel from the roof panel of the Sport Exige directly into the
six carbon fibre air trumpets. The dry-sump engine, with a bore of 89.0 mm and stroke of 93.7 mm is water cooled
and also uses an oil-water heat exchanger to efficiently cool the oil. The whole engine is controlled by a Motec
M600 electronic engine management system fitted inside the cockpit. The power is transferred from the engine to
the rear wheels via a single mass stepped flywheel, AP Racing twin-disc cerametallic race clutch and Hewland
NLT sequential six-speed dog type transmission (with in-line shift mechanism). The gearbox itself is cooled
through an oil-water heat exchanger. A limited slip differential (separate power and brake ramp angles) completes
the powertrain package.
Design
The one-off racecar has been designed by Barney Hatt (Principal Designer for Lotus Design), under the
direction of Russell Carr (Chief of Design). Taking the already aerodynamic road going Exige, Hatt designed the
Lotus Sport Exige with the requirements to carry the design of the Exige and the brand attributes of Lotus into
a competitive racecar. Russell Carr explains the work needed to design the Lotus Sport Exige: "The objective was
to create a dramatic design and to take into account aerodynamic criteria to produce a race car that was not only
competitive but also stunningly good looking. General motorsport regulations also had to be adhered to so the
fact that the resulting racecar looks like a natural competition evolution of the road going Exige is a testament
to the purity and effectiveness of the original design."
Dimensions
The Lotus Sport Exige is slightly longer (350 mm) and wider (100 mm) than the road-going Exige to accommodate
the larger engine, wider track, longer wheelbase and to optimise the aerodynamics. The length is mainly from the
cockpit rearwards but the short rear overhang design of the road-going Exige is maintained.
Lotus Sport Exige Technical Specifications
Engine
- Narrow (56°) angle V6 engine, water-cooled
- 2,998 cc, stroke 93.7 mm, bore 89.0 mm.
- Max. power: 400 hp (296 kW or 405 PS) at 7,750 rpm
- Max. torque: 294 lb.ft (398 Nm or 40.6 kgm) at 6,500 rpm
- Max. rpm: 8,250 rpm
- Four valve technology
- Oil-cooler (oil-water heat exchanger)
- Dry-sump lubrication
- SRE Multi-roller barrel throttle bodies
- F1 style airbox and air snorkel
- Motec M600 electronic engine management system
- Required fuel quality: 98 octane super unleaded
- Race exhaust: multiple pipe manifold, open exhaust
- No catalytic converter
Transmission
- Hewland sequential six-speed dog type transmission, straight cut gears
- In-line shift mechanism
- Gear ratios: Crown wheel & pinion gear 9:35
- 1st gear 12:36
- 2nd gear 15:33
- 3rd gear 18:30
- 4th gear 20:26
- 5th gear 24:26
- 6th gear 26:24
- Oil-water heat exchanger
- Single-mass flywheel
- AP Racing twin-disc cerametallic race clutch
- Limited slip differential (separate power and brake ramp angles)
- Rear-wheel drive
Chassis
- RHD race vehicle developed from Lotus Exige road car
- Lotus bonded aluminium chassis and composite crash structure
- Bolted on 8-point roll cage (in accordance with FIA-Regulations 2004)
- Three-point AP Racing air jack system
Bodywork
- Weight optimised and widened Exige
- Lotus Design RTN "Z-preg." carbon fibre bodywork
- Aerodynamically developed front splitter and rear diffuser
- Adjustable carbon rear wing
- Racing bucket seat (driver side only)
- Six-point seat belt, prepared for using HANS Safety System
- Removable steering wheel (with quick-connect coupling)
- Electrical fire extinguishing system
- 100 litre FT3 safety fuel cell with quick refuelling system
- Total weight of bodywork excluding doors ~ 44 kg
Suspension
- Double wishbone front suspension with spherical bearings
- Adjustable front anti-roll bar
- Non-PAS
- Double wishbone rear suspension with spherical bearings
- Adjustable rear anti-roll bar
- Ohlins ST44 3-way adjustable dampers
- Coil over damper springs front and rear
- Suspension adjustable for ride heights, camber and castor
Braking system
- Non-ABS system
- AP Racing pedal box with brake balance bar and AP Racing cylinders
- Aeroquip style brake lines
- Front AP Racing six piston brake calipers
- AP Racing vented discs diameter: 344 mm
- Aluminium disc bells, race brake pads
- Rear AP Racing four piston brake calipers
- AP Racing vented discs diameter: 330 mm
- Aluminium disc bells, race brake pads
Rims/Tyres
- OZ Racing Chrono single-piece cast magnesium rims:
- F - 8.8J x 17 ET40
- R - 11.25J x 18 ET50
- Yokohama tyres
- F - 250/610-17
- R - 280/650-18
- Single central wheel nuts with locking devicep
Electrical System
- Motec M600 engine management
- Stack display with integrated data recording
- Raychem 25 system wiring looms and Mil spec connectors
- Red Top battery: 12 Volt, 50 Ah
- Twin Bosch fuel pumps with change over switch
- Floor mounted carbon fibre centre switch console
- Circuit breaker switches (no fuses)
- 120 Ah Alternator
Dimensions
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Lotus Sport Exige |
Production Lotus Exige (Road Specification) |
Wheelbase |
2500 mm |
2300 mm |
Track - front |
1545 mm |
1457 mm |
Track - rear |
1528 mm |
1507 mm |
Overall length |
4142 mm |
3797 mm |
Overall width (door mirrors excluded) |
1840 mm |
1727 mm |
Overall width (door mirrors included) |
1850 mm |
1850 mm |
Overall height |
1125 mm |
1159 mm (mid-laden) |
Overhang - front |
950 mm |
805 mm |
Overhang - rear |
692 mm |
692 mm |
Vehicle mass - unladen (running order, full tank of fuel, no occupants, no luggage) |
850 kg |
875 kg (no options) |
About Group Lotus plc:
The main operating subsidiary of Group Lotus plc is Lotus Cars Ltd., which has two operating divisions -
Lotus Cars and Lotus Engineering: Lotus Cars builds and commercialises Lotus sports cars, Elise and Exige;
builds sportscars for General Motors and manufactures the advanced composite front and rear crash structures
for Aston Martin V12 Vanquish. Lotus Engineering provides comprehensive and versatile consultancy services to
many of the world's OEMs and Tier 1 suppliers, offering a full engineering service from initial concept and
project design through development to full production prototype build.
Lotus Sport
Lotus Sport is the performance arm of Lotus Cars Ltd and is located at the Norfolk Head Office next to
the famous Hethel test track. The department designs and builds modified versions of the standard Lotus road
cars with special emphasis on upgraded performance, improved ride and handling packages and race specific
safety equipment. Individual performance parts to customise or upgrade a vehicle are available via Lotus
Sport and its workshops can service, repair, restore or upgrade a standard road or competition Lotus. In
addition, Lotus Sport provides a range of driving packages using the renowned Hethel test circuit, including
driver training and corporate days, as well as offering enthusiasts a guided tour of the Lotus factory.