Jaguar XJR-9LM Specifications

Specification

Designer:

• Tony Southgate

Engine:

 

• 
  
• Type: 60º V12 overhead cam, naturally aspirated
• Construction: aluminium-alloy block and heads, forged-alloy pistons, nitrided forged EN40B steel crankshaft with Holset harmonic damper, seven main bearings, cast-iron ‘wet’ cylinder liners, Cosworth pistons
• Bore x Stroke: 94mm x 84mm
• Displacement: 6995cc
• Compression Ratio: 12.8:1
• Valve Gear: two titanium valves per cylinder operated by single chain-driven overhead camshaft per bank of cylinders
• Fuel System: Bosch electronic fuel injection and Zytec electronic engine management
• Ignition: Lucas electronic
• Max Power: 745bhp (560 KW) @ 7250rpm
• Max Torque: 610 lb ft (828 Nm) @ 5500rpm
• BHP/Litre: 107 bhp / litre
• Weight: 240kg including clutch and accessories
• Transmission:
• Type: 5 speed manual March/TWR

Body/Chassis:

• Type: carbonfibre and Kevlar composite construction monocoque chassis with engine used as rear suspension load bearer; lightweight composite and carbon fibre reinforced body with undersurface incorporating ground-effect venturi channels to the rear and regulation flat floor
• Downforce:
  • 150mph: 1562 lbs (625 lbs drag)
  • 180mph: 2250 lbs (900 lbs drag)
  • 200mph: 2777 lbs (1111 lbs drag)
  • 240mph: 4000 lbs (1600 lbs drag)
  • Lift-to-drag Ratio: 2.5:1

Running Gear:

• Steering: rack and pinion
• Suspension:
  • front: independent with magnesium hub-carriers and wide-based pushrods to adjustable spring/Koni damper units mounted horizontally in centre of car
  • rear: independent with double wishbones actuating adjustable spring/Bilstein damper units mounted outboard to allow maximum width of venturi tunnels;
  • magnesium uprights all round
• Brakes: AP four-pot calipers with 13 inch diameter cast-iron ventilated discs
• Wheels: Dymag 17 inch diameter
• Tyres: Dunlop Denloc Kevlar, 17 inch diameter front, 18 inch diameter rear

Dimensions and weight:

• Length: 189.8 in (4821 mm)
• Width: 79.5 in (2019 mm)
• Height: 40.6 in (1031 mm)
• Wheelbase: 106.7in (2710mm)
• Track: 64.2 in (1631mm) front / 62.0 in (1575 mm) rear
• Weight: 2,315 lb (1050kg)

Performance:

• Max Speed: 236 mph (380 km/h) in Group C Le Mans low-drag trim
• Power to weight ratio: 0.85 bhp / kg

Aerodynamics

Nose-mounted oil and water radiotors were used with hot air ducted out beneath the car. Engine air was drawn in from an air box mounted above the engine cover. Spats over the rear wheels helped reduce drag and the smallest possible rear wing was used in the Le Mans specification, centrally mounted on a single pillar.

Transmission

With 700 bhp passed through wide, sticky racing tyres an extremely durable transmission system was required. TWR turned to March Engineering, the Bicester-based racing car constructor, to provide the gears which were installed in TWR’s own casing. A right-hand gear change was employed with the linkage running back through the bulkhead behind the driver.

Rear-end access for maintenance and replacement of damaged components was obviously a factor to be taken into account during Le Mans in particular, where it was not unknown for transmission systems to be entirely rebuilt during the course of the race.

Drive was taken to the rear wheels through an AP Racing triple-disc clutch.

Suspension

The Jaguar XJR-9LM was fitted with a sturdy, unequal-length wishbone suspension system on all four wheels with strong, but light, magnesium alloy hub-carriers.

At the front the adjustable shock absorbers were mounted horizontally in the centre of the car, operated by push-rods. In the rear the shock absorbers and spring units were housed within the wheel offsets to allow for optimum airflow through the underbody venturi tunnels.

Engine

The XJR-9LM’s engine was a derivative of the production 5.3 litre V12 used in the XJS road car, but enlarged to seven litres for racing purposes. The cylinder block, heads and pistons were all manufactured from aluminium alloy, whilst the connecting rods were manufactured from steel and titanium. The forged steel crankshaft ran in seven main bearings.

With a 12.8:1 compression ratio, the V12 engine developed 700bhp at 7,000rpm and 610 ft lb torque at 5,600rpm. By the end of the season development on the engine resulted in an additional 40bhp and 200rpm.

Like the production engine, there were only two valves per cylinder, with a single camshaft on each bank of six cylinders.

The fuel-injection system was controlled by an electronic engine management system, with the induction tract in the centre of the “V” and individual injectors for each cylinder. Air was drawn through a single filter.

The exhaust system was made up from individual pipes joining in groups of three before passing to a single exhaust pipe on each cylinder bank.

Dry-sump lubrication was used with a side-mounted radiator used to cool the oil.

Chassis

The structural integrity of the central monocoque chassis section, manufactured from carbonfibre and Kevlar composites, was graphically demonstrated in 1987 when Win Percy’s XJR-8LM crashed heavily on the Mulsanne straight during the Le Mans race. Although the car rolled several times, Percy was able to walk away unscratched.

The V12 engine was attached to the central monocoque as a load-bearing structure, supplemented by steel bars converging backwards from the rear bulkhead.

 

The body construction used lightweight composite and glassfibre reinforced carbonfibre. The underneath of the car incorporated large ground-effect venturi sections as well as the required flat surfaces as dictated by the regulations.