420 Si - 1986 to 1988
The 420Si was the logical evolution of the 420S, with the Weber injection in place of the traditional carburettors. The power gain was about 10HP, with the subsequent increase in maximum speed up to 228km/h (141.7 mph).
External colours and interior trim were now more elegant compared to the rather loud 420S, and sales figures were consequently boosted. The full leather interior assembled by hand was standard. The 420Si could still be easily identified due to its black grille and absence of chromes.
Technical data
| 0-60 mph | 0 to 100 km/h in 6.2 sec. |
| Bodywork | four-door saloon seating five |
| Bore and stroke | 82x63 mm |
| Brakes | discs all round, A.T.E. (IH type) dual circuit, servo-assisted; two rear drum brakes for emergency and parking |
| Brakes front | |
| Brakes rear | |
| Chassis | monocoque steel construction |
| Compression ratio | 7.8:1 |
| Cooling system | water-cooled, centrifugal pump |
| Displacements (unitary) | |
| Dry weight | 2,590 lbs (1,175 kg) |
| Engine | 90° V6, light alloy block and head, Aluminum-Nigusil cylinder liners |
| Engine weight | |
| First race | |
| Front Tyres | |
| Front suspension | MacPherson struts, dual-rate telescopic dampers, coil springs, anti-roll bar |
| Front track | 56.77 in. (1,442 mm) |
| Fuel & lubricant | |
| Fuel feed | 2 IHI turbos, two air-to-air intercoolers |
| Fuel tank | 18.04 Imp. gal. (82 litres) |
| Gear ratios | |
| Height | 51.57 in. (1,310 mm) |
| Ignition | Weber electronic injection, electronic ignition |
| Kerb weight | |
| Length | 173.23 in. (4,400 mm) |
| Length-Width-Height | |
| Lubrication | full-flow filter lubrication |
| Maximum power | 220 bhp at 6,250 rpm |
| Maximum torque | 25.8 kgm (187 lbs/ft) at 3,500 rpm |
| Model | 420 Si |
| One mile | 0 to 1000m in 26.9 sec. |
| Production dates | 1986-1988 |
| Production start | 1986 |
| Quarter mile | |
| Rear Tyres | |
| Rear suspension | semi-trailing rear arms mounted on a rear subframe, coil springs, dual-rate Bilstein gas telescopic dampers |
| Rear track | 57.20 in. (1,453 mm) |
| Reduction | |
| Steering | rack and pinion (power assistance to order) |
| Timing gear | three valves per cylinder (two intake, one exhaust), twin overhead camshafts |
| Top speed | over 141.5 mph ( 228 km/h) |
| Total displacement | 1,996 cc |
| Transmission | 5-speed ZF + reverse, rear-wheel drive and Sensitork differential, 3.73:1 ratio |
| Tyres | fr/rear 205/60 VR 14 |
| Weight distribution | |
| Wheelbase | 102.36 in. (2,600 mm) |
| Wheels | light alloy, 6.5" J x 14" |
| Width | 68.11 in. (1,730 mm) |