Bizzarrini always had a keen sense for racing. Despite working for both Ferrari, then Lamborghini, and contributing to their best models, the 5300 was the first car fully credited to his name . Eventually, the very same companies he worked for would become key competition.
As an underdog, Bizzarrini knew what he was up against, but he never stopped trying.The 5300 project stems from a long and complicated relationship between Bizzarrini, Giugiaro at Bertone and Renzo Rivolta. These three worked together to create the Iso Rivolta 300, a flagship car for Iso, having a welded sheet steel monocoque and Corvette V8.
Due to sporting nature of the chassis and the reliability of its American power, Bizzarrini wanted to go endurance racing, but Rivolta who owned Iso did not agree.Fortunately, by 1963, Rivolta was finally convinced to finance the development of a more sporting Iso Rivolta. The result was the precursor to the 5300 GT, the Iso Grifo.Both Bizzarrini and Bertone worked extensively on two different cars which debuted at the 1963 Torino Motor Show. To satisfy Rivolta, both a competition Grifo A3/C and a 2+2 Grifo A3/L were displayed.
These cars had distinctly different bodies and different design objectives, but were in many ways the same. Both Grifos were styled by Giugiaro at Bertone, used the same chassis and the same engine. Immediately after the successful show, both versions of the Grifo were put into production.All of the chassis were built in Bizzarrini’s workshop at Livorno. Iso provided the engine and other components. Drogo manufactured and delivered bodies for the competition cars to Livorno for final assembly. The 2+2 grand tourer A3/Ls, were finished at Bertone where Bizzarrini shipped bare chassis.Bizzarrini really considered the A3/C to be his own. So much so, he registered the mark Grifo and put his own badges on some of the cars.
After the death of Renzo Rivolta in 1965, the relationship between Bizzarrini and Iso ended with only 25 Grifos built. Bizzarrini then sued Iso to acquire the necessary parts and finish 50 cars himself at Livorno. Without Iso, all cars after chassis #0224 were named Bizzarrini 5300 GTs and finally Bizzarrini’s name graced his design.The Iso Grifo AC3/C and Bizzarrini 5300 GT were very much the same product. When Bizzarrini took over full production, he had all the bodies assembled by Carrozzeria BBM instead of Drogo. Small design details were introduced on the BBM body including different door handles, rear lights and front signals.
The Grifo and 5300 where based on the Iso Rivolta 300 chassis. It was a welded sheet steel tub having a fully independent suspension by double wishbones in the front and a De Dion axle in the rear.
These same characteristics were lent to the Grifo and 5300, albeit in a shorter chassis.Unlike all Italian sports car tradition, Bizzarrini used an American engine for the 5300, specifically the Chevrolet V8. With this engine came a host of benefits: it was ample in power, cheap to purchase and maintain, simple to tune and best of it all, it would run reliably all day and all night. After moderate tuning, the engine provided 365 bhp, keeping it well ahead of Ferrari’s 275 GTB.Using lessons learned with the Ferrari 250 GTO, Bizzarrini pushed the heavy V8 far back into the engine bay as possible.
When combined with the side-mounted gas tanks the weight balance of the 5300 was very close to a perfect, even during different fuel loads. One major drawback to this engine location was the intrusion of interior space which put the pedals at about mid-engine. Being so close to the engine, road going 5300s got very hot in the cockpit despite added interior ventilation.Like a race-car, the interior space seemed planned as an afterthought. Both the speedo and tach were located centrally with temperature and oil pressure gauges in front of the driver. Furthermore, very little insulation was provided to stop heat and noise from reaching the occupants.
Due to homologation requirements, the Iso Grifo debuted on the track as a prototype. This classification put the Grifo against Ford’s seven liter GT40 and Shelby’s Cobra. The Grifos excellent aerodynamics, powerful engine, independent suspension and reliability made it an excellent endurance GT car and prototype sports for that matter.
Due to homologation requirements, the Iso Grifo debuted on the track as a prototype. This classification put the Grifo against Ford’s seven liter GT40 and Shelby’s Cobra. The Grifos excellent aerodynamics, powerful engine, independent suspension and reliability made it an excellent endurance GT car and prototype sports for that matter.1964 was very much a development year for Bizzarrini. The team managed to attain 14th place at Le Mans and finished 19th at the Nurburgring 1000km. The next season started out on a rough note, with a car getting destroyed at both Sebring and Daytona.
After the first two races, older cars were used. At Le Mans, a class victory was scored with the retirement of the seven liter GT40s. This first in class highlighted the racing achievements achieved with the Grifo.The following two years, Bizzarrini raced the 5300 sporadically throughout the season. Unfortunately no major victory was achieved despite several extensive modifications including fiberglass bodies and seven liter engines. The seven liter car was unable to race the 1967 Le Mans because it did not pass scrutineering.Unfortunately, finances were the main problem hindering the 5300 GT’s racing program. Bizzarrini had a limited budget, but was one of the few independents who could make such remarkable machines, attain respectable results in motor sport and sell the very same product to the US and abroad.
Sources & Further Reading
Biro, Pete. ‘Iso Corsa A3-GT’.Sports Car Graphic. Sept 1964.
Cornil, Etienne. ‘Three Iso Grifos’.Sporting Motorist. Sept 1964.
Goodfellow, Winston. Iso Rivola: The Men, The Machines. Giorgio Nada Editore: March 2002.
Hales, Mark. ‘GTO vs Bizzarrini’. Octane, Issue 01. July 2003.
Olczyk, Philippe et al. Bizzarini, the genius behind Ferrrari’s Success. World Print Ltd: 2001
In Detail
engine
Chevrolet Corvette V8
position
Front Longitudinal
aspiration
Natural
valvetrain
2 Valves per Cyl w/Pushrod Acutuation
fuel feed
Quad Weber 45 DCOE
displacement
5359 cc / 327.0 in³
bore
101.6 mm / 4.0 in
stroke
82.5 mm / 3.25 in
compression
10.5:1
power
302.0 kw / 405.0 bhp @ 6000 rpm
specific output
75.57 bhp per litre
bhp/weight
331.97 bhp per tonne
torque
494.87 nm / 370 ft lbs @ 3600 rpm
redline
6200
body / frame
Aluminum Body over Sheet Steel Semi-Monocoque w/Tubular Steel Superstructure
driven wheels
RWD by Salisbury Hypoid Differential w/Limited Slip
front tires
6.00Lx15 Dunlop R7
rear tires
7.25Lx15 Dunlop R7
front brakes
Dunlop Discs w/Vacuum Assisst
f brake size
mm / in
rear brakes
Inboard Dunlop Discs w/Vacuum Assisst
r brake size
mm / in
front wheels
F 38.1 x 17.8 cm / 15.0 x 7 in
rear wheels
R 38.1 x 22.9 cm / 15 x 9 in
steering
Burman Recirculating Ball
f suspension
Unequal A-Arms w/Coil Springs,Koni Telescopic Dampers, Anti-Roll Bar
r suspension
De Dion Axle w/radius Arms, Coil Springs,Koni Telescopic Dampers
curb weight
1220 kg / 2690 lbs
wheelbase
2446 mm / 96.3 in
front track
1410 mm / 55.5 in
rear track
1430 mm / 56.3 in
length
4369 mm / 172.0 in
width
1730 mm / 68.1 in
height
1110 mm / 43.7 in
transmission
Borg Warner 4-Speed Manual
gear ratios
2.54:1, 1.92:1, 1.51:1, 1.10:1, :1
top speed
~305.8 kph / 190.0 mph
0 – 60 mph
~5.0 seconds
0 – 100 mph
~13.5 seconds
Story by Richard Owen for Supercars.net
Auction Sales History
1965 Iso Grifo A3/C Bizzarrini BO213 – did not sell for $1,100,000 Giotto Bizzarrini built 20 Iso Grifo A3C race cars with the rare Drogo riveted alloy body. Lightweight aluminum Drogo riveted body designed and built by Carrozzeria Sport Cars Modena. Completed in late 1964 and delivered new to Auto Becker in Germany in January 1965. Owned by race car driver Pierre de Sibenthal from the 1970s until the 1980s. Sold to a new owner in the late 1980s in Italy. 5.3L engine with 400 HP. 2012-2013 comprehensive ground-up restoration by Autocostruzioni Torino, Italy. 2013 Pebble Beach Concours d’Elegance. Documented and backed by certificate of conformity. Auction Source: Monterey 2014 by Mecum Auctions
