1967 ISO Grifo GL

History

In 1962, the Milan car manufacturer ISO introduced its second model, the Grifo. The first was the Rivolta. Giorgio Giugiaro of Bertone designed the body and Giotto Bizzarrini, creator of the Ferrari GTO, engineered it. The Grifo was powered by a Chevrolet 5.3 liter V8 and sat atop a shortened Rivolta platform. The engine was placed in the front and drove the rear transaxle. The Borg-Warner T4 4-speed manual gearbox lacked overdrive, a problem that would cause it problems in future endurance racing. At speeds, the driver had to back off the accelerator pedal to help preserve the life of the engine. With over 400 horsepower from the GM small-block and a weighing less than 2200 pounds, the vehicle was able to achieve 190 miles-per-hour.
The Grifo was sportier than its predecessor and was available in two version, luxury and sport. The luxurious Grifo was dubbed the A3/L while the sportier version received the title A3/C. Iso produced the Grifo A3/L while Bizzarrini developed the A3/C.

In 1964 it was entered in the 12 Hours of Sebring as well as the grueling and fiercely competitive 24 Hours of Le Mans race. During its racing career it would capture a fourth overall but first in class victory at Le Mans.

During the production lifespan of the Grifo, around 22 versions of the A3/C were constructed. Due to disagreements, Bizzarrini and Rivolta parted ways in 1965. A deal was struck where Bizzarrini could still produce the Grifo A3/C cars but was unable to use the name. The new name was the Bizzarrini 5300 GT and American GT.

In 1968, a 6998 cc V8 engine became available and was later modified to 7443 cc.

By Daniel Vaughan | Oct 2007

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Founder and head of Iso S.p.A. of Bresso, Renzo Rivolta began his business 'Isothermos' in refrigerators before moving on to automotive design. The company well known for their bubble cars and motorcycles, but their claim to fame lies in their performance GT car Iso Grifo. In 1960 Renzo was immensely attracted to the British Gordon GT prototype. Borrowing it for inspection Renzo also borrowed some of its ideas for a new high performance 2+2 sportscar. Already quite famous for producing the stunning Rivolta IR300, Iso Rivolta took it a step further and introduced the glorious Grifo in 1963.

Giotto Bizzarrini, the famous freelance Italian engineer had worked for Ferrari, but left to set up 'Prototipi Bizzarrini' in Livorno, Tuscany. It was here that Giotto designed and consulted for big names like Lamborghini, ATS and Iso Rivolta. Young Giorgetto Giugiaro at Bertone designed the body while Bizzarrini focused on the mechanical side of the sportscar. What developed was the stunning Grifo A3L (L for Lusso/Luxury) prototype coupe. Debuting in Turin in 1963 the vehicle wouldn't be production ready for another two years. The A3L curvy fastback featured a body of steel with large engine-cooling grids in the front fenders, a Kamm-style tail and twin-mouth grille. Sharing a great distinction with the Chevrolet Corvette, the two-door coupe Grifo was well known for its sleek appearance.

The Grifo was also designed in a race version called the A3/C (Corsa) with a spectacular modified alloy body. Bizzarini had been the designer behind the Ferrari 250 GTO and he dubbed the A3/C his 'Improved GTO'. One of the first front-mid-engined cars ever built, the A3/C's engine was moved back about 16 inches. Both version of the Grifo were built simultaneously and both models were debuted the same year. Bertone debuted the Grifo A3/L prototype at the Turin Auto show, and Iso unveiled the under construction competition version; the Iso Grifo A3/C. The motoring press was incredibly impressed with both models.

Though design tweaks to the prototype were made, Iso set about getting the Grifo A3/L production ready. In an attempt to make the Grifo 'less aggressive' a facelift was in order, and it transformed the model into an even more stunning model. The Grifo shared the Rivolta's running gear and suspension, but was tuned for higher performance.

Considered by some to be the most elegant-looking Gran Turismo (GT) supercar ever created, the Grifo received the Chevrolet Corvette's 327 V8 (5.4 L) engine. Speedy and reliable, the engine was either 300 or 350 hp and was mated to a Borg-Warner 4-speed toploader. The engine was ordered in the U.S. but would be taken apart precisely and blueprinted before being installed, in the same way as the Iso Rivolta GT. With a top speed of 171 mph, the supercar had over 400 hp and weighed less than 2,200 pounds. The font suspension was through conventional wishbones and coil springs, while at the rear was a coil-spring De Dion live axle located by radius arms and Watt linkage. The brakes were four-wheel discs.

Giotto spent all of his time and energy on the A3/C while Renzo Rivolta focused on the A3/l. This unfortunately brought some tension between the two men. The Grifo GL was produced at Bresso while the A3/C was produced at Piero Drogo's Sports Car of Modena under the watchful eye of Giotto. The A3/C was raced at Le Mans (Edgar Berney/Pierre Noblet) in 1964. The prototype raced well until brake issues required a two-hour pit stop before the car finished in 14th place. A disagreement between Renzo and Bizzarrini ended the cooperation in 1965 and the production of the street Grifo GL and the competition Bizzarrini A3/C was separated. Only 22 examples of the Bizzarrini Grifo A3/C were constructed.

Giotto produced a line of Bizzarrini 5300 Stradas and Corsas from the improved A3/C. The 'Grifo' name was dropped from any connection to Bizzarrini at this time. Bizzarini went on building both Bizzarrini Stradas and Corsa and had the alloy bodies constructed by BBM of Modena.

Bizzarrini introduced the scaled-down 1900 'Europa' in 1967. Some models received Alfa Romeo engines while some received a tuned-up version of the Opel 1900 engine. About seventeen models were produced which made it one of his most rare designs ever. The Barchetta version, the P538 was even more rare with only three models produced. Around 155 Bizzarrini Stradas and Corsas were built before Bizzarrini closed down in 1969 due to bankruptcy. The remaining parts and cars were sold off.

In production form the Grifo developed 390 hp and could reach 68 mph in first gear. A singular Grifo A3/L Spyder was debuted at the Geneva auto show by Renzo. In 1965 production of Iso Grifo GL began. The first ever Grifo with Targa Top was shown in Turin October 1966 and would be one of 13 Series I Targas ever built. Four series II Targas were eventually produced.

The interior of the Grifo was incredible comfortable and could rival many Italian supercars of the day. The Grifo handled beautifully and was a solid supercar that appealed to nearly everyone. Because of its low build of only 47 inches, the Grifo was extremely fast and had excellent aerodynamics. Unfortunately the Iso marque wasn't as prominent as Maserati or Ferrari and attracting orders from the affluent customers that they needed was difficult.

The Grifo 7 Litro was debuted in 1968 powered with a Chevrolet L71 big-block engine, a Tri-Power version of the 427 engine. Changes had to be made to the car for this seven-liter engine to fit included the addition of a hood scoop. The 7 Litro had a claimed top speed of 186 mph and produced 435 hp at 5800 rpm. The Grifo Series II was introduced in 1970 and included styling updates in the nose section of the car that was sleeker and hid hide-away headlights. Four Targas were built in this new series. The engine for the IR-9 'Can Am' version was switched from the 427 engines to the newer 454 engine. Iso began to use small-block Ford Boss 351 engine and could be easily recognized by their taller hood scoop. In 1972 production ceased and Iso S.P.A. closed its doors in 1974 during the oil crisis.

During its production span a total of 413 Iso Grifos were produced. 322 Series 1 models, 78 Series II cars, 90 if these being the 7 Litri. 23 of the Series II 5-speeds, and 4 of the Series II Targa models were produced. Today the Grifo is an incredible collectible due to its extremely rare production.

Sources:
http://auto.howstuffworks.com/iso-sports-cars.htm
http://en.wikipedia.org/wiki/Iso_Grifo
http://gtdemo.com/history-of-the-iso-grifo/

By Jessica Donaldson

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