Biturbo Si (2500) - 1987 to 1991
When Maserati introduced Weber-Marelli fuel injection on the Biturbo, the more powerful Biturbo S version received the same treatment. Announced in December 1986 and dubbed Biturbo Si, the 2.5-litre version for the export markets was good for 188 hp at 5,500rpm, a quote still lower than that of the Italian market-only 2.0-litre, since power was reduced by the catalyst emissions control system.
The twin intercoolers were now mounted at the front of the engine. Exterior colours were either red, gunmetal or black over grey and there was a discreet spoiler on the tail. The interior sported a revised seat configuration and leather trim, and there was optional power steering.
Technical data
| 0-60 mph | |
| Bodywork | three-box two-door coupé seating five |
| Bore and stroke | 91.6 x 63 mm |
| Brakes | discs all round, dual circuit, servo-assisted, additional drums on rear wheels for handbrake |
| Brakes front | |
| Brakes rear | |
| Chassis | monocoque steel construction |
| Compression ratio | 7,4:1 |
| Cooling system | water-cooled, centrifugal pump |
| Displacements (unitary) | |
| Dry weight | 2,632 lbs (1,194 kg) |
| Engine | 90° V6 |
| Engine weight | |
| First race | |
| Front Tyres | |
| Front suspension | MacPherson struts, dual-rate telescopic dampers, coil springs, anti-roll bar |
| Front track | 56.76 in. (1442 mm) |
| Fuel & lubricant | |
| Fuel feed | electronic injection, two IHI water-cooled turbos, two air-to-air intercoolers |
| Fuel tank | 17.58 Imp. gal. (usable) |
| Gear ratios | |
| Height | 49.41 in. (1,255 mm) |
| Ignition | electronic |
| Kerb weight | |
| Length | 163.50 in. (4,153 mm) |
| Length-Width-Height | |
| Lubrication | full-flow filter lubrication |
| Maximum power | 188 hp at 5500 rpm |
| Maximum torque | 236.5 lbs/ft at 3,000 rpm |
| Model | Biturbo Si (2500) |
| One mile | |
| Production dates | 1987 to 1991 |
| Production start | 1987 |
| Quarter mile | |
| Rear Tyres | |
| Rear suspension | semi-trailing rear arms mounted on a rear subframe, coil springs, dual-rate hydraulic telescopic dampers |
| Rear track | 57.07 in. (1450 mm) |
| Reduction | |
| Steering | mechanical rack and pinion (power assistance to order) |
| Timing gear | three valves per cylinder (two intake, one exhaust), twin overhead camshafts |
| Top speed | over 135 mph (217 km/h) |
| Total displacement | 2491 cc |
| Transmission | 5-speed ZF + reverse (3-speed automatic to order), Torsen limited-slip differential |
| Tyres | fr/rear 205/55 VR 14, Michelin MXV |
| Weight distribution | |
| Wheelbase | 98.97 in. (2,514 mm) |
| Wheels | magnesium alloy, 7" J x 14" |
| Width | 67.48 in. (1,714 mm) |