Biturbo Dossier
The true story of the Trident's V6

Original Italian text by by Gaetano Cesarano, with the contribution of Claudio Ivaldi and Dario Battocchio

The following is my English translation of an article previously published in the quarterly Italian motoring magazine Granturismo, and published with their kind permission.

Pride and Passion ...
... are among the principal motivators that can induce one to purchase a Biturbo, drawn by the brutal power of its supercharged V6, but not without making certain sacrifices in order to maintain it in perfect working order.

Having already created a number of sports cars under his own name, Alejandro De Tomaso could never have dreamed of being remembered, by many, as the creator of the most controversial model to bear the symbol of the Maserati trident. The former Argentinian racing driver and entrepreneur had in fact revitalised the historic Modenese company in 1976, following a failed period of Citroen ownership and the brief stewardship of GEPI, the Italian government agency designed to avoid redundancies at companies facing closure. To resolve the fate of the company once and for all, and carry its production numbers to a more industrial level, De Tomaso planned to build a "compact" five-seater coupe powered by a 2-litre V6 engine, with its power output entrusted to not one, as was the fashion at that time, but two turbochargers, each feeding one bank of cylinders.

The engine still retained the 90° V6 format of the earlier Merak and was characterized by an untried technical solution. It adopted a valve train operated by a single overhead camshaft per cylinder bank, with three valves per cylinder, two intake (a small one and a larger one which together provide a swirl effect that increases combustion efficiency) and a single exhaust valve operated by a single cup, a system patented by De Tomaso. This engine had a cubic capacity of 1996 cc - chosen in order to avoid "the heavy" 38% Value Added Tax that penalized cars powered by engines of over two litres and fed by a single twin-choke Weber carburettor "blown" by two IHI turbochargers. Power output reached 180 bhp at 6000 rpm, giving the new Maserati, thanks to its contained weight of 1086 kg, a decidedly sporty character. Performance figures declared were a maximum speed of 215 km/h and acceleration from 0 to 100 km/h in 6,5 seconds.

This sophisticated drive unit, was matched with a classic mechanical formula; a front longitudinally mounted engine, rear wheel drive, independent front suspension, a rear subframe with tailing-arm suspension, in a rather traditional three-box design - drawn up by designer Pierangelo Andreani - with an aggressive frontage that created a pleasant 'family feeling' alongside the imposing Quattroporte design of Giugiaro. The interior also showed obvious references through the Trident badges on its chrome fittings, instrument gauges and steering wheel. The commercial name for the new two-door, bearing in mind its peculiar mechanical features, was "Biturbo". The press preview took place, not by chance, on the 14th December 1981 - coinciding with the 67th anniversary of the founding of Officine Alfieri Maserati - while presentation to the general public was reserved until the "display window" of the Geneva Motor Show in March of 1982.

A phenomenon of fashion

Potential customers responded with enthusiasm and rushed to place orders, practically "in the dark", having been attracted by its significantly competitive, though not yet official price, of less than twenty million Lira. The production numbers assumed for the Biturbo, some thirty cars a day, were not however compatible with the artisan capability of the Maserati factory in Modena, from where the Quattroporte exited at a rate of only three units a day. Production was therefore transferred to the Innocenti factory at Lambrate, another marque rescued by the Argentinian entrepreneur, where engines and suspension units would arrive, having previously been assembled in Modena.

Deliveries began in May of 1982, by which time the list price had risen to a figure of 22.236.000 Lira (around GB £10,500), while during the course of 1983, prices increased month by month until it rose to over 27.000.000 Lira (around GB £13,000), which included "mandatory options" such as: air conditioning (1.939.000 Lira), magnesium alloy wheels (713,000 Lira), central locking (194,000 Lira), electric windows and tinted glass (451,000 and 194,000 respectively), adjustable dipped headlights (194,000) and hand-stitched upholstery (823,000).

Unfortunately for early customers, in return for driving one of the most sought after cars at the time, they were soon confronted with wideranging reliability problems. This emanated from a hurried development programme, down to De Tomaso's wish, in pushing forward its presentation date. The sophisticated engine, therefore, required a certain care - above all when starting up and switching off, especially after having exploited the twin turbochargers' powerful performance. A performance that wasn't too obvious in the hands of many "ordinary" drivers who had chosen the Biturbo more as a "fashion" statement than for its "sporting" spirit, and were ambushed by ruinous over-revving, facilitated by the great responsiveness of the Modenese V6.

The range is extended

On the 14 December 1983, to underline the sporting spirit of the Biturbo, an "S" version was introduced. The Maserati V6 had now gained more horsepower, a stomping 205bhp! At the same time, a four-door version was revealed, named the "Biturbo 425". Powered by the 2.5-litre V6 - already in use on "Export" models - it developed 200 bhp. With a wheelbase lengthened by approximately 9 cm and an overall length of 4.4 m, these saloons were well received by the general public, especially in Italy with the "Biturbo 420", with its two litre engine, that would appear in Maserati's 1985 range, and again in 1986 when placed alongside the more aggresive "420 S".

The sharp lines of the Biturbo lent itself ideally to the design of an open version. In 1982, a cabriolet version prepared by Carrozzeria Embo as a pre-series prototype, had been presented at the 'Salone di Torino'. It was however Zagato who De Tomaso commissioned to produce the Biturbo Spyder, an agile 2-seater (plus 2 occasional seats) built on a strengthened coupe platform, but with a wheelbase shortened by 11.4 cm. The Spyder was fitted with a small hood that could be comfortably lowered, along with the quarter glass, behind the seats. The "Biturbo Spyder" was introduced at the 'Salone di Torino' in 1984, even though deliveries didn't start until many months later. This was indeed the model that best captured the thoroughbred spirit of the V6, highlighted by the chassis' shortened wheelbase, and best demonstrated its 'wedge-shaped' line.

A decline in desire

Although the Spyder gained modest commercial success within its class, the expansion of the range with a four-door and the sporty "S" wasn't sufficient to stimulate interest in the Biturbo. Its initial faults, and though soon resolved, unwise pricing policy, along with an unacceptable poor quality of finish on a car that at that time was competing in the luxury class with the near "perfection" of the German coupes. Furthermore, the concessionaires, most of whom were from the Innocenti network, were not best equipped to properly support such demanding customers.

While sales in Italy had "cooled off" - after having surpassed 6,000 units in 1984, the North American market had been literally "burnt", due largely to several cases of onboard fires with the first Biturbos exported. Those fires were caused by bad thermal insulation on the catalytic convertors - that in 1985 required an official recall of all models sold in the U.S. The obvious result being numerous claims for compensation, with a ruinous loss of image for Maserati's overseas market. If that was not enough, a serious outbreak of strikes at the Lambrate factories, had caused not only delays in production, but a significant drop in quality control.

In the meantime, a water cooling system for the turbochargers - soon to be adopted in the entire production range - had been introduced on the "228": an imposing coupe mounted on the long platform of the "425" that retraced, with a few minor changes, the lines of the original Biturbo.

An injection of reliability

By the end of 1986 the "i" versions were introduced, equipped with an electronically controlled Weber-Marelli fuel injection system. And so the cold starting problems of the early carburated versions were resolved, producing a more reliable and regular operation of the little V6. In 1987, having benefitted from the same cure, the sports models were immediately renamed “Biturbo Si” and “420 Si”.

Subsequently the "430" was revealed to the public: a new saloon, derived from the "Biturbo 425", that along with a new fuel-injected 2.8-litre engine, underwent a successful restyling of the frontal area and new interior finish. But not even the continuous mechanical development by the Modenese technicians - who for this latest car had redesigned the front suspension geometry and differential assembly, and fitted ventilated front disc brakes and 15" wheels - could succeed in reviving the poor image of the Maserati V6, even though reliability and performance had been greatly improved. Its position wasn't improved by an increase in price that pushed it into an inevitably higher position in the market.

New models and more powerful engines

At the end of 1988, the "Si" models - last testimony to the commercial name Biturbo - gave way to the "222" and "422", two and four-door respectively, characterised by a less angular front-end, as with the "430". For the foreign market and with the same 2790 cc engine, the latter was placed side by side with the "222" and "Spyder i". For the Italian market they would adopt a 2-litre engine producing 220 bhp. Recollecting the "S" series, in 1989 the "2.24v." was introduced, and thanks to a new 2-litre engine with four camshafts and four valves per cylinder, produced even more power (245 bhp) compared to the "222" from which it derived. It offered on request, an innovative electronically adjustable suspension system. For a four-door sports version, we would have to wait until 1990, with the introduction of the "4.24v." - characterised by its multi-spoke 16-inch alloy wheels and, for the first time on a saloon, a small boot-mounted spoiler. For the foreign market the "222 SE" - with same styling as that of the "2.24v." - replaced the previous "E" model. Similarly the "430" was restyled to resemble the "4.24v."

The winds return to blow once more

At the beginning of 1988, an idea was suggested by Carrozzeria Zagato - who two years earlier had designed a hard-top for the Spyder which never reach production - that gave life to the "Karif", a berlinetta built on the short platform of the Spyder, but with a rigid steel roof. It was named after the strong wind that blows in the gulf of Aden during the monsoon season, thus resuming a Maserati tradition of the Sixties. The 2.8 litre engine - derived from that of the "430" - was officially credited with 285 bhp. With the name of a wind, the Shamal, a new coupé, was introduced in December of 1989. Built on the established short chassis of the Karif, the Shamal boasted a powerful V8 boosted by twin turbochargers. The original lines of the coupé were entrusted to Marcello Gandini whose new design produced a "muscle" supercar, emphasized by its widened wheel arches. The controversial "popular" soul of the Biturbo gave way to a true thoroughbred, returning the Trident brand to its tradition of exclusive sportscars.

Gandini's cure

In 1991 the two-door range saw the introduction of the Racing - powered by 283 bhp version of the Biturbo 24-valve V6 engine coupled to new Getrag gearbox - at that time the most powerful production 2-litre on the market. As for the 2.24v. from which it derived, it was given a new "Shamal style" front-end treatment with the use of small polyelliptical headlights, a wind deflector at the base of the windscreen, and a larger radiator grille.

In the months that followed, the aesthetic restyling of the Racing was extended to the 2.24v., 4.24v. and Spyder. The same styling updates were given to the 2.8-litre engined range reserved for export, that were seen alongside the 18-valve 222 SR, the 430 4v., and the 222 4v., the latter two developing 279 bhp thanks to the use twin overhead camshaft and four valve per cylinder heads. On the same stylistic theme as the Shamal, but using the longer coupe chassis, the Ghibli was launched, prepared with a rousing evolution of the 2-litre V6 producing 306 bhp, claiming the 2-litre power output record set by the Racing.

The baton passes to Fiat

At the end of January 1993, Alejandro De Tomaso was struck down with a cerebral stroke and forced to retire from the company, yielding his share quota to Fiat, who had already acquired 49% a few years earlier. 1994 would see the first fruits of the new Fiat management with a major revision of the Ghibli and the presentation of the Quattroporte IV, a prestigious name for a new car once again designed by Gandini and equipped with the "heart" of a Biturbo. In 1998, the Casa del Tridente overhauled its range, as it set its sights on a higher segment in the market. The Ghibli exited the scene, a car that can be considered the last descendant of the Biturbos. However, it would still be the V8 Biturbo engine of the Shamal that would power the new 3200 GT until 2002.

Evolution of the Species

1981:   On the 14th December, the Biturbo was officially presented to the press, forerunner to the largest model range in Maserati's history. A 1996 cc V6 engine, with single overhead camshafts per cylinder bank driven by a timing belt, with three valves per cylinder and a twin-choke Weber carburettor supercharged by two IHI turbochargers. It was fitted with a five-speed ZF gearbox. For the interior, the dashboard and door trim were in a "briar-wood effect" synthetic material, the dashboard and centre console trimmed in a simulated leather, and seats and side panels in velour - a leather trim was also available as an option. The instrument panel was rectangular in shape, the four-spoke steering wheel had a moulded polyurathane hub, and the dashboard had a digital clock by Veglia Borletti mounted at its centre.

1982:   In April, the first examples of the new car from the 'Casa del Tridente' were consigned.

1983:   During the year marketing of the Biturbo for export began. Examples assigned for export were equipped with a specific 2491 cc engine, obtained by increasing the bore to 91.6 mm, with cast iron liners. Different also were the transmission ratios, and the diameter of the intake and exhaust valves. Versions destined for the Swiss and Swedish markets were equipped with a special device to facilitate cold starting, and a system designed to eliminate fuel vapours from the plenum chamber. Models assigned to the USA were moreover equipped with an exhaust system with air injection and two-way catalytic convertors. Leather trim was standard and included various aesthetic differences in order to conform with U.S. vehicle safety regulations (more protruding bumpers, laterally mounted sidelights and "sealed beam" front headlights).

From engine No. 3001, an MABC system (acronym for Maserati Automatic Boost Control) was adopted, to electronically regulate the turbochargers' boost pressure.

1984:   A sports version of the Biturbo became available, thanks to the addition of two air/air intercoolers mounted on either side of the carburettor, and fed by means of two very visible bonnet-mounted NACA vents. The 2-litre V6, with a re-mapped MABC engine management control unit, now boasted a power output of 205 bhp. The "Biturbo S", was available in two colours; pastel red and metallic black, and had a characteristic aesthetic treatment with glass window surrounds, bumpers and lower side panels painted in dark grey, as was the honeycomb mesh front grille, save for the chromed Trident. Suspension was lowered and the newly designed 6½Jx14" alloy wheels, incorporating a burnished finish, were shod with Pirelli P7 205/55 tyres. Carello front fog lights, upholstery in a Missoni fabric and briar-wood inserts were standard.

Along with the "Biturbo S", there appeared a four-door saloon: the Biturbo 425. Mounted on the platform of the coupé, but with a wheelbase lengthened by approximately 9 centimetres and a pronounced rear-end overhang. The frontal area and rear light clusters remained unchanged, however the new external door handles were no longer recessed. There were also important modifications made to the interior - that, also in this case, saw the introduction of the new Missoni fabric - and a new elliptical shaped instrument panel housing the speedometer, rev counter, and turbo boost gauge. Grouped on either side were sited the oil and water temperature gauges to the left, and voltmeter and fuel level gauges to the right. Above these gauges a row of warning lights stretching from side to side, while the push-button switches for the heated rear window, front and rear fog lights, hazard warning light, boot and fuel flap releases were now located in the centre console next to the air conditioning controls. Close to the gear lever were the switches controlling the height and inclination of the driver's seat, while that for the passenger seat inclination was sited in the door arm rest. Analogue and oval in shape, a new Lassale clock, signed "Maserati", replaced the Borletti Vegliaflash.

From a mechanical point of view we saw the introduction of the 2.5-litre engine, already employed on the "Export" versions of the Biturbo, that for the Italian market produced some 200 bhp. Different from the coupés were the suspension calibration, transmission ratios and wheel size (now similar in design to those of the Biturbo S) and tyres, 6Jxl4" and 205/60 respectively. A Sensitork differential (sensitive to torque), constructed under licence by Gleason, replaced the Salisbury differential adopted on the two-door versions. By the end of the year, the alloy wheel design of the Biturbo "Model Year 84" became unified with those of the S models and 425, having however a "silver" finish and dimensions of 6Jx14". Rear seat headrests and seat belts were no longer standard fitments.

1985:   With similar changes already made to the Biturbo, that in the meantime was made available to the overseas market, and with a 3-speed ZF automatic transmission as an option, the Biturbo 425 was also now available outside Italy, bringing for the Swiss and Swedish markets the same modifications made to the corresponding 2.5-litre two-door models. During the year, the Biturbo was however subjected to a significant number of improvements. From a mechanical point of view, the second series, known also as the "Biturbo II", was characterized by its engine with Nigusil treated aluminium liners, a system patented by Moto Guzzi (i.e. Guzzi Nickel Silicon), with water-cooling replacing oil-cooling for the two turbochargers, and a Sensitork differential. With the exception of the Biturbo S II, now credited with 210 bhp and equipped with leather upholstery as standard, the layout of the instrumentation followed that of Biturbo 425 with an elliptical shaped instrument panel and analogue "Maserati" clock, now illuminated by means of a push-button switch situated in the centre console. For the Italian market, the Biturbo 420 would enter the range in May: identical to the 425, but equipped with a 2-litre engine, in order to avoid the punitive Value Added Tax.

Produced by Carrozzeria Zagato, September saw the Biturbo Spyder finally revealed to the general public, with a wheelbase 11.4 centimetres shorter than the coupè, from which it derived, and a redesigned rear-end. The manually operated fuel filler flap, lacking the trident, was positioned behind the hood. Mechanics and interior, with upholstery in beige leather as standard, were the same as those of the Biturbo II, while the size of the wheels and tyres were identical to those of the "S" versions. This last version was now made available to the foreign market, where the mating of two air-to-air intercoolers to the catalyzed 2491cc engine guaranteed a maximum power of 192 bhp. Sadly, the 420 S was never to reach the United States.

Thanks to the enterprise of Kjell Qvale - Maserati distributor for the "West Coast" who in the Nineties gave name to the new "Mangusta" - the Biturbo E was introuced to the USA. Reserved for the North American market in a limited series of 500 examples, thanks to the adoption of Spearco air/water intercoolers, it boasted a maximum power of 205 bhp, in spite of the anti-polution system. In fact it was a standard Biturbo, modified on site by the dealers, whose aesthetic characteristics vaguely resembled that of the Biturbo S. Bumpers and side skirts were painted in matt black, but the window surrounds and radiator grille (characterized by its honeycomb design) were chromium plated. The suspension was modified with lowered springs and stiffer shocks-absorbers, and an anti-roll bar of increased diameter. On the trunk lid appeared "E" and "Liquid Intercooler" badges. It was fitted with 6½Jx14" burnished alloy wheels with 205/60 tyres. Fog lights and a three spoke wood-rimmed Nardi steering wheel were standard.

On the 14 December the 420 S was introduced, a sport variant of the Biturbo 420 with a similar layout to that of the Biturbo S and an engine producing 210 bhp. Available only in dark bordeaux dark and metallic silver, it sported a leather and Alcantara interior as standard, different designed rear seats, and 7Jx l4" alloy wheels with polished rims.

1986   Finally an "Export" versions in right-hand drive became available for the Biturbo, Biturbo 425 and Spyder. Externally one immediately noticed the inverted windscreen wipers. On sale in Italy by the end of the year were the "Biturbo i" and "Biturbo 420 i" models; equipped with an electronically controlled IAW (Weber-Marelli) fuel injection system were characterized by improved reliability and a slight increase in power thanks to the use of intake and exhaust valves of a larger diameter (the new cylinder heads derived from those of the 2.5-litre engine). In the meantime, the Spyder also became available for export, with a carburated 2491 cc engine.

In the USA - where the antipollution standards imposed the use of a Weber 34 carburettor (instead of 36) - along with the open version, the Biturbo 425 finally arrived. Cruise control and power steering were standard. The aesthetic differences, as with the coupe, were limited to the use of "sealed beam" headlights, larger sized front indicators and "side-markers" elegantly set into the bumper's rubber inserts. A third brake light was fitted to both, that on the Spyder being positioned at the rear of the hood.

Thanks to a direct initiative by the English importer, "Special Edition" Coupé and Spyder models were created - characterized by the use of BBS cross-spoked split-rimmed alloy wheels, a "Biturbo S" radiator grille, colour-coded headlight surrounds and a Zender aerodynamic body kit.

1987   The use of a fuel injection on the sportier models in the range, gave life to the "Biturbo Si" and "420 Si" with a power output of 223 bhp, and cylinder heads with intake valves of equal diameter. The body treatment resembled that of previous "Biturbo S" with burnished window surrounds and honeycomb radiator grille. The NACA air vents on the bonnet now had a purely cosmetic function, since the two air-to-air intercoolers had been resited behind the radiator grille. All models were fitted with Carello fog light and 7Jxl4" alloy wheels with mirror polished rims. The two-door models - fitted with a rear spoiler on the boot lid - were available in red, black and metallic grey with the bumper and lower side panels in a contrasting colour, while the saloon versions in a darker shaded metallic grey and pastel black, had lower side panels and bumpers in a matching colour. The interior had newly designed seats (with a very sporty profile for the coupé models) and a different gear lever with a larger moulded knob. The 420 had magnolia coloured upholstery in leather and Alcantara, while the exclusive "Biturbo Si Black" had an interior in an unusual shade of beige. Both models had briar-wood trim (rounded edge on the saloons) on the dashboard and door panels.

Maserati's range for the export market, continued with the use of the 2491 cc engine with IAW electronic fuel injection, was now composed of the 425 i, the Spyder i and Biturbo Si, that in the latter case - differed from the models sold in Italy as they no longer had NACA vents on the bonnet.

1988   Now at the top of the range we found the "430" saloon. The engine - derived from the previous fuel injected 2.5-litre V6 with twin intercoolers - now had a cubic capacity of 2790 cc and a maximum power output of 250 bhp. The cylinder heads, derived from those of the "Si" models, had intake valves of equal diameter. The body, also derived from that of the 425 that it was about to replace, introduced interesting aesthetic innovations to the frontal area. The edges of the front bonnet and wings were rounded off, as were the headlight surrounds and honeycombed radiator grille. The application of a chrome trim enriched upper part of the bumpers. Part of the standard equipment were the two aerodynamic electrically controlled side mirrors and five-bolt 15" alloy wheels. As well as an exhaust system with two twin tailpipes, from a technical point of view we saw a new front suspension design named "Meccanica Attiva", ventilated front discs and a limited-slip Ranger® differential, whose principle function - though similar to the previous Sensitork - was a series of central gears surrounded by six satellite helical gears in a "star" pattern and working on a common axle guaranteeing greater reliability. There were two alternative interior trims available, essentially a difference in seat design, classic or sports, taken, as was the gear knob, from the two and four-door "Si" models. Noticeable, also, was the use of polished wood, on the handbrake lever, steering wheel rim and centre console trim, that housed a new air conditioning control unit, equipped with push-buttons controls and an electronic temperature display window. The analogue clock now had a more pronounced casing and was now connected to the car's 12 volt electrical system. The "Si" models were now fitted with a passenger side rear view mirror and air conditioning with electronic controls, while on the Coupé one noticed the aerodynamic rear-end, already in use on the Spyder, in the vicinity of the spare wheel.

In the meantime at the Geneva Motor Show, named after a strong southwesterly wind on the southern shore of the Gulf of Aden, the "Karif" was introduced: a new berlinetta mounted on the short platform of the Spyder. Its front end had the rounded edges previously seen on the successful restyling of the 430 from which it also took the new geometry for the front assembly, along with ventilated front brake discs and 15" alloy wheels. Externally one noticed that the bumpers and lower side panels were no longer in contrasting colours, the aerodynamic rear view mirrors and a redesigned engine bonnet with two NACA vents for improved heat dispersion. The interior mirrored the wood trim from the 430. Moreover, a showy louvered grill on the rear bumper separated the two twin tailpipe exhaust ports. The 2.8-litre engine, also derived from that of the 430, was officially credited with 285 bhp.

That summer we saw the introduction of the 222 and 422 - respresenting the two and four-door models, destined to progressively replace the "Biturbo", that remained in the range while supplies lasted. Compared to the "Si" models from which they derived, the engine and interior remained unchanged, with leather upholstery available only as an option, and rounded edge briar-wood trim also on the Coupé. The analogue clock was the later type with 12 Volt connection. With the modified front-end styling of the 430, and lower side panels no longer in contrasting colours, the loss of the NACA vents on the front bonnet and the return to chrome trim for the window surrounds, the line became noticeably simplified. Both models were equipped with electronically controlled aerodynamic rear view mirrors, while still the exclusive prerogative of the saloon, were the 15" wheels coupled to the new "Meccanica Attiva" front suspension, the ventilated front brake discs and power steering. To the 222 was added a showy spoiler on the rear boot lid and 4-bolt silver-finished alloy wheels.

Updated with the same aesthetic and interior changes as the coupé and saloon, the Spyder had adopted 15" wheels, and for the Italian market, the same 220 bhp 2-litre engine as the 222 and 422.

1989   The cars destined for export - characterized by the two exhaust exit ports, the 15-inch wheels and ventilated front brake discs - were now endowed with the same 224 bhp catalyzed 2.8-litre engine that powered the 430, the Spyder and new "222 E", that differed from the other models not destined for the U.S. market were equipped with a "Karif type" front bonnet with two heat extractors. A new four-speed automatic transmission was available on request.

With the departure of the "Si" models from the range, the trade name "Biturbo" was abandoned. The arrival of the "2.24v.", testimony to the earlier sports models, was powered by a high performance 1996 cc engine, with two camshafts per head and four valves per cylinder, giving a maximum power output of 245 bhp. A suspension system with electronically controlled adjustable shocks-absorbers was available on request. There were several updates, stylistically beginning with the more enveloping bumpers, having a different profile incorporating rubber inserts, at the front end, new trapezoidal fog lights (that were now standard equipment) and, at the rear, the two twin-exhaust exit ports.

The burnished finish, along with the lower side panels, radiator grille and headlight surrounds presented therefore an obvious reminder of the previous "S" models. To signal the presence of a more profiled sideskirt, a rear spoiler different in design from that of the 222, and the addition of an element of conjunction between the rear light clusters. The front bonnet with the heat extraction vents and 15-inch alloy wheels are instead identical to those of the Karif and 222 E. The interior offered a leather and Alcantara upholstery as standard, as well as the centre console, handbrake lever, and steering wheel rim in wood. In the meantime, the 222 was also fitted with a "meccanica attiva" front end with ventilated disc brakes and the same 15-inch wheels as those mounted on the 422 saloon.

1990   Equipped with the 2-litre 24-valve engine, a new variant of the four-door saloon was presented: the "4.24v.". Its aesthetic treatment recalled that of the 2.24v with the larger wrap-around bumper (in this case in the same colour as the bodywork), more pronounced sideskirts and molded trim for the window surrounds and front grille. On the rear boot lid there appeared a small aerodynamic "lip", while the newly designed seven-spoked 16" OZ alloy wheels had the five securing bolts hidden behind a hub cap simulating a single nut. The interior, followed that of the 430, with leather upholstered seats and a new briar-wood finish trim for the ashtray. Suspension with electronically controlled adjustable shock-absorbers was now standard equipment on the 2.24v. By the end of the year, Maserati had ceased selling cars to the United States. In the meantime, the Spyder was now available in Italy with the 2.8-litre engine, while the "222 E" and a restyled "430" were made available for the export market: the first - whilst maintaining the mechanics of the previous "E" - adopted the bumpers of the 2.24v. colour-coded with the bodywork, the other, from an aesthetic point of view, was now identical to the "4.24v." and no longer had the characteristic chrome trim on the top edge of its bumpers. Both models were fitted with 15" wheels. The dashboard for models with a beige leather interior, were partially trimmed in grey Alcantara for an anti-reflective function.

1991   With the trade name "Racing", there appeared in the range a more sportier version of the 2.24v. Available only in pastel red and metallic black, it differed from other models by its new front panel, larger, of a greater dimension and same colour as the body, housing new front light clusters with polyellipsoidal headlamps. To the base of the windshield had been applied a small deflector covering the windscreen wipers, while examples in black had "smoke" coloured rear lights. The 16" alloy wheels were the same as the 4.24v. The engine represented the ultimate evolution of the six cylinder 24 valve Biturbo: redesigned crankshaft and combustion chambers, re-profiled camshafts, new forged pistons, lightened con-rods, sodium valves and new turbochargers allowed the power output to reach 283 bhp, making the Maserati Racing the most powerful production "2-litre" on the market. New also was the five-speed Getrag gearbox. On the inside we found the seats from the 2.24v. completely upholstered in leather and no longer in partial Alcantara. The instrument panel was enriched with the addition of an external temperature gauge located in a central position close to the turbo boost gauge. The steering wheel now had a larger four-spoke hub incorporating two horn buttons on the upper spokes. Rocker switches for the electric seat adjustment and windows were positioned on the centre console in an identical position to those on the saloon.

The four-door range was extended with the introduction of the "4.18v." fitted with the 18-valve engine of the 422, and with the aesthetics of the 4.24v. (from which it essentially differed by the presence of a sole twin exhaust exit port, its 15" wheels, and with a leather interior only available on request). The true innovation was the presence of an ABS braking system that would never be available, even on request, on any other model of the "Biturbo range". Finally, a single key operated the ignition and doors. For the Spyder, available only with the 2-litre and 2.8-litre 18-valve engines, came the adoption of the wrap-around bumpers incorporating trapezoidal fog lights and the same fascia panel mounted between the rear light clusters as the 2.24v. At the end of the year a 2.8-litre engine with 24-valves and four overhead camshafts was introduced. Destined for export, it powered the new "222 4v." and "430 4v.", that boasted a maximum power of 279 bhp, a Getrag gearbox and electronically controlled suspension. The aesthetic treatment was clearly inspired by that of the Racing with polyellipsoidal front headlight clusters, larger grille and fluted windscreen wipers. The seven-spoke OZ alloy wheels now had a diameter of 16", while the instrument panel contained an outside temperature gauge. At the same time the "222 SR" - with the 2.8-litre 18-valve engine, 15" alloy wheels and an identical aesthetic treatment to that of the 4-valve series - replaced the previous SE models as an "entry level Biturbo" for the export market. All models were equipped with a steering wheel identical to that of the Racing, from which they also took the layout of switches on the centre console. In the meantime production of the 222, 422 and Karif models ended, but remained in the listings while stocks lasted.

1992   The antipollution legislation that came into force from 1st January 1993 saw the end of production for the 2-litre 18-valve engined models. At the same time, the 24-valve models were made available with catalytic convertors. In the autumn, for the Italian market, we saw a restyling of the range, that now adopted the frontal aspect of the "Racing" for the "Model Year 92". The seven spoke wheels were moreover extended to the 2.24v. and Spyder, that now had a windscreen with a burnished surround and without the chrome bits on the fixtures. A Getrag gearbox replaced the now obsolete ZF box. The steering wheel and layout of control switches on the centre console became unified with those models assigned for export.

1993   At the end of January, Alejandro De Tomaso is forced to retire into private life, the result of a cerebral stroke. The Fiat group acquired total control of Maserati. With the exception of the Spyder, production stopped for the 2-litre 24-valve models, but they would remain in the listings until early 1994. For export, the 2.8-litre version of the Spyder, the 222 4v. and 430 4v., remained.

1994   Production also ended for the Spyder (in Italy, the 2-litre version survived until January of 1996) and the "4v." destined for export. The latest testimonies to the evolution of the "Biturbo" were the Ghibli and Quattroporte IV designed by Marcello Gandini.

Which one to choose?

Familiarising oneself with the different Biturbo models is not so easy, mainly due to the numbers produced over time. The spirit of the collector will lean towards a first series model - perhaps in Bordeaux, at the time not too common in Italy, but today perhaps the sober metallic tones will appear more attractive - putting aside something for the odd headache, on top of routine maintenance and tuning. One who doesn't mind passing unnoticed will probably plump for one of the two or four-door "S" versions. More suitable for frequent use are without doubt the injection models, that also benefit from reduced fuel consumption. The connoisseurs will go for the "Si Black" version, due to its limited production and exclusive finish, or among the four-door versions, a 430, for its stylistic and mechanical refinement.

The last series with the four-valve engines, will unfortunately be subject to a higher car tax. If you don't have that problem, the 283 horsepower of the Racing will no doubt have an irresistible appeal to the "maniacs" of power and exclusivity, and they can be still found at tempting prices. The same goes for the Karif, than in early examples can already enjoy the fiscal benefits reserved for "historical" status, and is destined to appreciate over the short term, even if its unconventional styling still promotes "discussion". The Spyders are appreciating in value, due to its pleasant combination of style and power that reached a maximum expression on the later models. Buying any Biturbo requires a lengthy and careful choice, coupled with a scrupulous verification of the condition of any proposed purchase, in order to avoid unpleasant surprises regarding repairs and spare parts, always very expensive, that represent the very limit in the introduction to car restoration.

Gaetano Cesarano, Claudio Ivaldi, Fabio Roberti

 BITURBO V6 Models  Production Engine Engine Type 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994
 Biturbo/ Biturbo II 9206 1996cc AM 452/09 * * * * *                
 Biturbo/ Biturbo II "Export" 4577 1996cc AM 452/09   * * * *                
 Biturbo 425 2052 2491cc AM 453/0     * * *                
 Biturbo S/ Biturbo S II 1038 1996cc AM 452/10     * * *                
 Biturbo S "Export"/ Biturbo E 1480 2491cc AM 453/0       * *                
 Biturbo Spyder 276 1996cc AM 452/09       * *                
 Biturbo Spyder "Export" 1049 2491cc AM 453/1       * *                
 Biturbo 420 2810 1996cc AM 452/09       * *                
 Biturbo 420 S 254 1996cc AM 452/10       * * *              
 Biturbo i 683 1996cc AM 470         * *              
 Biturbo 420 i 1124 1996cc AM 470         * *              
 228 i 469 ? 2790cc AM 473         * * * * * * * *  
 Biturbo Si 992 1996cc AM 471           * *            
 Biturbo Si "Export" 50 2491cc AM 472           * *            
 Biturbo i Spyder 297 1996cc AM 470           * *            
 Biturbo i Spyder "Export" 122 2491cc AM 472           * *            
 Biturbo 420 Si 524 1996cc AM 471           * *            
 Models  Production Engine Engine Type 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994
 Biturbo 425 i 320 2491cc AM 472           * *            
 430 995 2790cc AM 473             * * * * * *  
 Karif 221 2790cc AM 473             * * * *      
 222 1156 1996cc AM 471             * * * *      
 222 E 722 2790cc AM 473             * * *        
 422 978 1996cc AM 471             * * * *      
 Spyder i 309 1996cc AM 471               * * * *    
 Spyder i "Export" 603 2790cc AM 473               * * * *    
 2.24v./ 2.24v. MY 1992 1401 1996cc AM 475               * * * * *  
 4.24v./ 4.24v. MY 1992 874 1996cc AM 475                 * * * *  
 222 SE 342 2790cc AM 473               * *        
 Racing 230 1996cc AM 490                   * *    
 4.18v. 77 1996cc AM 471                   * *    
 222 SR 210 2790cc AM 473                 * * *    
 222 4v. 130 2790cc AM 477                   * * * *
 430 4v. 291 2790cc AM 477                   * * * *
 Spyder MY 1992 200 1996cc AM 475                     * * *
 Spyder MY 1992 "Export" 220 2790cc AM 473                     * * *
 Models  Production Engine Engine Type 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994



The powerful V6 turns out to be almost "bomb-proof" if maintained correctly, i.e. observing the correct service intervals for changing the timing belt and the oil, which MUST be totally synthetic (Selenia Racing Oil 10W/60, Castrol Edge Sport 10W/60, Shell Helix Ultra Racing 10W/60, or the equivalent are recommended). The IHI turbochargers turn out to be equally sturdy, especially the later water-cooled versions. If possible, it is advisable to look for an example with a well documented and regular service history. Considering the high cost of an engine rebuild (it can cost as much as 7,000/8,000 euro!), it's worthwhile paying great attention to its condition, calling in the help of an experienced mechanic, or at least checking for any pale blue smoke from the exhaust tailpipe on a warm engine, inevitably signalling the need of a turbocharger rebuild (around 500 euro each!). One should pay great attention when looking at any early example, that was often in the hands of an enthusiastic but inexperienced owner. For the latter, it is worth remembering that adjusting the carburettor is laborious due to difficult access. Moreover, problems in adjusting the twin vacuum advance distributor, than many have eliminated by substituting this type of distributor with the later single vacuum advance distributor (it will however be necessary remove various air hoses and the often seen sealing of a hole in the carburettor's cover).

As for the transmission, the high torque available on the different models has always subjected the differential to a severe test, that is often the Achilles' heel of the more overstrained cars. Special attention must be paid to any noises: Whistles and hisses indicate the need of an imminent overhaul costing not less than 3,000 euro. If there is a "knock" noise during acceleration and deceleration: originating from the drive shaft and universal joints, be prepared for a complete overhaul. There are very few problems with the manual gearbox: both the ZF or the later Getrag are sufficiently strong to cope with the liveliness of the various models. One must pat particular attention to cars fitted with the Borg Warner automatic transmission, that was available with the 2.5-litre engine, that at the time turned out to be understrength for the characteristics of the car. The slightest play in the steering wheel can often be attributed to the rack and pinion gears in the steering box, even if in some cases it's sufficient to change the mounting brackets. As for the braking system, the non-ventillated front discs of the first models often overheated and warped, when driven by someone with little regard.

Dirt accumulated on the crankshaft sensor through normal useage can often cause the erratic operation of the rev counter. Oil leaking on to the exhaust manifolds, leading to a smoke-filled engine bay, can instead be traced to a leaking rocker cover gasket. The exhaust system, depending on the model, can differ in the length and diameter of its pipes but, with the exception of the 430 - whose two rear silencers have a different design to that of the later 4.24v. - are relatively reasonable and readily available. The use, during refuelling, of an approved lead substitute (perhaps together with an un octane booster) is recommended for the 2.0 and 2.5-litre 18-valve engines produced up until March 1987, and for the 2.0-litre 24-valve engine produced up until January 1992. In this case the only real alternative is to replace the existing valve seats with those of a hardened material.

The Electrical System

Careful attention must be paid to the fusebox, that only too often can be responsible for the car breaking down: it often causes a few headaches in the operation of certain controls, but in more serious cases, can leave you stranded by the roadside. It's a good idea to check the operation of the electric windows, replacing the electric window motors is a real pain, and that the cooling fans are operating correctly corrected activation of the impellers of cooling, switched by a relay. Failure of the light bulbs in the rear light custer, normally indicated by the car's "Test" circuit, can often be attributed to poor terminal connections. In this case, to restore their function, a careful check of their contacts in the boot is sufficient.

Wheels and Tyres

>Even though the alloy wheels had a variety of finishes, the designs were more or less the same. However, special attention must be paid to fitting the correct wheel size, as the various models were fitted with different widths. Hard to fine, however, are the tyre sizes 205/60 and 205/55 VR14, adopted until 1989. In this case, it is possible to obtain clearance from the factory to fit the more common 195/60.

Bodywork and Interior

Early examples didn't have adequate anticorrosion protection, therefore it is necessary to pay great attention the undertray, the "A", "B" and "C" pillars, the wings, doors and bonnets. Special attention should also be paid to the windshield and rear window, both attached with adhesive, as their surrounds may be subject to corrosion. The situation got better for the later injection models, as the body treatment improved. Considering the Biturbo's liveliness and the ease at which the rear-end could break-away, it is well to check the undertray for ominous signs of it having "left the road", and for not having suffered, also at the rear-end, close "contacts" with guard-rails and pavements. The interior merits a special mention, for which the materials used were rather sensitive to aging, and the special artifical Nappa leather used on earlier versions - that covered the centre console, doors and dashboard - are now difficult to replace. The easiest and more long-lasting solution, but obviously more expensive, is to replace it with real leather, but it won't be easy to find the exact shades. In the same way it is considered normal to see a deterioration in the Alcantara seat upholstery of the more recent examples. Attention must be paid to making sure that the aesthetic trim conforms with correct model and production period. It's not uncommon to find up-dates carried out on the bodywork with bonnets, grilles, bumpers and spoilers from the sports or more recent models, with the possibility, in this last case, than it has been carried out to round off the sharp edges on the frontal area of "pre '88" cars. The benefits of pursuing with any restoration, that should be assessed on each model, is often a matter for debate.

Spare Parts

In some cases, identical original parts, the same as those used on more popular cars, can be of help in maintaining cars at an acceptable operating cost. One must however be careful: in the case of the clutch slave cylinder for the ZF gearbox and the fusebox, similar parts used on certain Alfa Romeo and Fiat models are unfortunately incompatible with those used on the Maserati. The same applies to the front headlamps, similar to those used on the Fiat 127 and 128, but equipped with an H4 socket for halogen lamps, and the side indicators, that "resemble" those of the Lancia Delta, Prisma and Thema, but have different mountings. The trapezoidal fog lights fitted on the 2.24v. are however identical to those on the Lancia Thema produced until to 1991, and the intergrated front sidelight/indicator lights for all models are the same as those on the Fiat 127 and 128. For the Spyder, the hood coupling system, including handles, are identical to those fitted to the open version of the Peugeot 205. The catalogues of the more well-stocked spare parts specialists often contain comparable accessories, above all Italian, from the Eighties for many other components such as: alternator, central-locking control unit, windscreen wipers and starter. For the push-button switches for the electric windows and electrically controlled seats we suggest you visit Look out for the characteristic Maserati analogue clock that is expensive to replace (300 euro), and of which there are several versions; i.e. with and without illumination, and powered by an independent battery cell or by the car's 12 volt electrical system.


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Copyright: Gaetano Cesarano, Claudio Ivaldi, Fabio Roberti - Granturismo Magazine - © 2009. All rights reserved.