Iso Grifo

Production period:	1964 to 1974
Class:	sports car
Body versions:	Coupe
Engines:	Gasoline  5.4-7.0 litres
Length:	4430-4600 mm
Width:	1770-1800 mm
Height:	1200-1230 mm
Wheelbase:	2500 mm
Curb weight:	1430-1610 kg

The Iso Grifo is a sports car built 1964 to 1974 built by the Italian car manufacturer Iso Rivolta. 

History

After the four-seater coupe Iso Rivolta IR 300 Iso 1964 presented the conceptually similar, but sporty designed two-seater Iso-Grifo coupe, a Gran Turismo for the wealthier man.

The prototype of the Grifo was shown in late 1963 at the Turin Motor Show under the name A3 / L (Lusso). This line largely corresponded to the later production model; only the front end differed by obliquely mounted headlights and a three-dimensional grille. Between the front wheel arch and the A-pillar there was a striking vent, which was covered with individual chromed struts and revealed the view of an exhaust pipe lying behind it in the style of American "Side Pipes". This design element was not adopted in series production.

Engineer Giotto Bizzarrini, a former Ferrari employee who left the factory of the Commendatore Ferrari in the dispute and opened his own design office in Livorno in 1963, was instrumental in the development of the Grifo. Bizzarrini designed a platform frame with box girders, which was similar to that of the Iso Rivolta IR 300 - except for a shortened wheelbase by twenty centimetres. American V8 engines were intended, and first from the Chevrolet Corvette the derived 5.4-liter V8. Other technical components were also bought in: The steering came from Burman, the limited slip differential from Salisbury, the disc brakes from Dunlop, manual gearboxes with five gears from ZF Friedrichshafen, four-speed gearbox from Mancie or Borg-Warner or a three-speed automatic from Borg-Warner gearbox Warner 4-speed all-synchromesh, gear ratios top 1.0, third 1.51, second 1.92, first 2.54, reverse 3.36; final drive Salisbury Powr-Lok hypoid bevel 3.07:1.The steering Burman recirculating ball type; wheel diameter 15.0 in.; brakes Dunlop discs front and rear, servo vacuum type, dimensions, front 11.75 in. diameter, rear 12 in. diameter; wheels cast alloy ventilated disc with centre-lock hubs, 6 in. wide rim; tyres Pirelli Cintürato HS tubed, 205-15 in.

The design of the coupe contributed, as with the Iso Rivolta IR 300, Bertone; in fact, it was a work by the young Giorgio Giugiaro, whom Bertone had recently appointed as Design Director. Giugiaro drew a low, cat-like hatchback body with gently rounded, tight-cut fenders and clearly recognizable, slightly inclined roll bar. On the low front you could see round twin headlights. The rear end was dominated by a large panorama window, which merged into a trunk attachment, and tapered significantly to the car end. Between the front wheel arches and the A-pillar large vents were provided, which were chromed on some models. The main features of the design go to the Pininfarina Rondine I a show car, the American Tom Tjaarda had designed in 1963 on the technical basis of the Chevrolet Corvette. 

The L version was the street model. In addition, a lighter and stronger racing variant was planned, the Grifo A3 / C (Competizione). This model started in 1964 at the 24 Hours of Le Mans. The Belgian Pierre Noblet and the Swiss Edgar Berney drove the car to the 14th place in the overall standings and to victory in the class for prototypes over 5-liter displacement. However, the racing concept was not pursued by Iso Rivolta. After a rift between company president Rivolta and Bizzarrini, the A3 / C was built by Bizzarrini on its own under the name Bizzarrini GT 5300 Strada (as a street version) and Corsa (an even sportier competition version with plastic body) sold.

1965 began the series production of the Grifo, which should last until 1974. In this time, there was a facelift: In 1970, Rivolta changed the front end by folding headlamps were introduced in the style of Iso Lele , which half obscured the headlights at rest. Apart from these minor external changes, Iso Rivolta has always offered new engines with different performances over time.

Main Versions

• A 3L Grifo (1965)
• Grifo GL (1965 - 1970)
• Grifo 7 liters (1968 - 1970)
• Grifo IR8 (1971 - 1974)
• Grifo IR8 Can-Am (1971 - 1974)

The basic model was initially Iso Grifo Lusso; later it received the additional designation IR 8. It was offered over time with various American engines between 5.4 litres and 5.8 litres displacement.The Iso Grifo was mainly sold as a closed two-seat coupe with hatchback body. Several vehicles had a steel sunroof on customer request, some were also equipped with a folding sunroof.Between 1966 and 1970, the Milan body manufacturer Pavesi made 17 Grifo with a Targa body. The vehicle remained unchanged with the exception of the removable roof part (between window frame and roll bar).

Even before the start of mass production Bertone presented in January 1964 before a Spyder based on the Iso Grifo. Apart from the roof section corresponded to the vehicle except for a few details of the later coupe, especially the front end was already at the standard level. The very elegant vehicle was not developed for series production; it remained with a single piece, which still exists today.

Between 1965 and 1972 as a standard engine a 5.4-liter eight-cylinder Chevrolet (Chevrolet Turbofire) was provided, which should afford by different tuning measures between 300 and 395 hp. 

• PERFORMANCE
  Engine capacity: 326.98 cu in, 5,358.60 cu cm
  Fuel consumption: 15.7 m/imp gal, 13.1 m/US gal, 18 1 x 100 km
  Max speed:136.7 mph, 220 km/h
  max power (SAE): 300 hp at 5,000 rpm
  max torque (SAE): 361 1b ft. 49.8 kg m at 3,200 rpm
  max engine rpm; 5,200
  specific power: 56 hp/l
  power-weight ratio: 10.1 lb/hp, 4.6 kg/hp
  max speeds: 53.4 mph, 86 km/h in 1st gear; 70.8 mph, 114 km/h in 2nd gear; 90.7 mph, 146 km/h in 3rd gear; 136.7 mph, 220 km/h in 4th gear

Between 1970 and 1972, there was also a 5.7-liter version of the Chevrolet Turbofire with outputs between 300 and 365 hp.

• Grifo GL 365
  max power (SAE) 365 hp at 6,200 rpm
  max torque (SAE) 361 1b ft, 49.8 kg m at 4,000 rpm
  max engine rpm, 6,200
  specific power, 68.1 hp/l
  fuel consumption 14.9 m/imp gal, 12.4 m/US gal, 19 1x100 km.
  max speed (I) 61.5 mph, 99 km/h, (II) 82 mph, 132 km/h, (III) 103.7 mph, 167 km/h,
  (IV) 161.5 mph, 260 km/h

During the year 1972, Iso switched to Ford engines. This may have been due to disagreements with General Motors over the payment of Chevrolet engines. The previous engine diversity was now history; for the Grifo there was between 1972 and 1974, only a 5.8-liter eight-cylinder Ford (Cobra jet) with 325 hp. The Borg-Warner automatic was replaced in the same year by a Cruise-O-Matic from Ford.

In addition to these basic models Iso offered between 1968 and 1972 a much sportier version of the Grifo. In each case was used on much larger engines from General Motors, which were more potent, but also heavier and some changes to the body, chassis and chassis required. The era of the big Grifo ended in 1972, when Iso changed its engine supplier: Ford's Big Block engines, used in the AC  428 for example, did not make it into the Grifo.

From 1968 to 1970 was in addition to the basic model of Iso Grifo 7 Litre on offer, a particularly sporty version of the Grifo with a much larger engine. A 7.0-liter version of the Turbofire engine (Turbo-Jet) with 406 hp was used. The big engine provided outstanding performance. Iso Rivolta announced a top speed of 300 km / h. This value is likely to be too high; Depending on the ratio of the rear axle, a maximum of 275 km / h was realistic. This, too, was still a value that the Grifo in the performance of Ferrari and Lamborghini. The huge engine did not fit under the standard bonnet of the Grifo, so that a sweeping scoop - in the factory had to be installed, which was detrimental to the line of the car. However, the 7 Litre were thermally very problematic in view of poor heat dissipation, although Iso had exchanged the standard oil pan of the Chevrolet Turbo-Jet for an enlarged, provided with additional cooling fins aluminium version. At high speeds, the engine and cooling water heated up a lot; it repeatedly came to the bursting of engines.

• The successor of the 7 Litre was the Grifo Can Am. It was offered between 1970 and 1972 and has now been powered by a 7.4-liter version of the Turbofire engine. Again, the maximum power was specified with 406 hp. The Can Am had as well as the 7 Litre the hood.

Between 1965 and 1974, a total of 412 Iso Grifo was produced, 17 of them as Targa. The 7-Litre version was produced in seventy copies, the Cam-Am version in twenty copies. From the late Grifo with Ford engines there were about 25 copies.