Engineering:Isuzu Piazza

Short description: Small, sporty 3-door liftback coupé which was manufactured by Isuzu.

Isuzu Piazza
Overview
Manufacturer	Isuzu Motors
Production	1981–1993
Assembly	Kawasaki Plant, Kawasaki, Kanagawa, Japan
Body and chassis
Class	Sports car
Chronology
Predecessor	Isuzu 117 Coupé

The Isuzu Piazza is a small, sporty 3-door liftback coupé which was manufactured by Isuzu from 1981 until 1992 in two generations. The Isuzu Piazza was marketed as the Isuzu Impulse in North America and as the Holden Piazza in Australia .

The first generation Piazza was a rear-wheel drive car, and in the United Kingdom it was the first widely available Isuzu passenger car. The second generation was available as front-wheel drive or all-wheel drive. It was the basis for the lower-priced Gemini Coupé, known as the Geo Storm in the US market.

As of 2010, the number of registered Impulses in North America totaled only 2,300, making Impulses very rare.

First generation (JR120/130; 1980)

First generation (JR120/130)
1988 Isuzu Piazza XE Handling by Lotus (JDM)
Overview
Also called	Isuzu Impulse (North America) Holden Piazza (Australia) Daihatsu Boon first generation
Production	1980–1990
Designer	Giorgetto Giugiaro at Italdesign
Body and chassis
Body style	3-door liftback coupé
Layout	Front-engine, rear-wheel-drive
Related	Isuzu Gemini
Powertrain
Engine	1949 cc G200Z I4 1949 cc G200WE DOHC I4 1994 cc 4ZC1-T turbo I4 2254 cc 4ZD1 I4 (U.S. only)
Transmission	5-speed manual 4-speed Aisin automatic
Dimensions
Wheelbase	2,440 mm (96.1 in)
Length	Base: 4,385 mm (172.6 in) US, turbo: 4,385 mm (172.6 in)
Width	Base: 1,655 mm (65.2 in)
Height	1,300 mm (51 in)
Chronology
Successor	Holden Calibra (Australia)

Rear view of a Piazza Nero XJ (Japan)

In 1978, Isuzu commissioned Giorgetto Giugiaro to design a new sporty car to replace the 117 Coupe (also a Giugiaro design). They delivered several T Series Chevettes (developed in 1973 in South America) to the Italdesign studio in Italy and allowed Giugiaro free rein over the design. The result of this effort was the wedge-shaped three-door hatchback called the Asso di Fiori ("Ace of Clubs") prototype and show car. It was shown at the 1979 Tokyo Motor Show to rave reviews. Giugiaro referred to the design as his fifth "Copernican revolution", integrating the design innovations of many different previous designs into one, mass producible, vehicle. Within 48 hours of its unveiling at the Tokyo Motor Show, Isuzu fast tracked the vehicle into production with minimal changes to the design. Items that remained were the single blade front windshield wiper, and an integrated steering wheel adjustment that also moved the instrument cluster, with wiper controls and exterior lighting controls installed just behind the steering wheel on either side, a feature that later appeared on the Ford Probe.

The first Piazza rolled off the production line in September 1980 in Fujisawa, Japan , available with either 120 PS (88 kW), 120 lb⋅ft (163 N⋅m) 2.0 L SOHC inline-four MPFI engine, a carryover from the Isuzu 117 Coupé, or a 135 PS (99 kW), 123 lb⋅ft (167 N⋅m) 2.0 L DOHC MPFI I4 engine. Five-speed manual and 4-speed automatic transmissions were available, and all models were rear-wheel drive. In April 1984, a 180 PS (132 kW), 185 lb⋅ft (251 N⋅m) turbocharged SOHC I4 engine was introduced, and the DOHC naturally aspirated engine was phased out in years that followed. Piazzas were available in a multitude of trim levels including Bella, XN, XJ, XE, XG, Nero, and others. There were three different suspension tuning levels, standard, Irmscher, and Lotus. Production continued through 1990.

Isuzu Impulse

For the US market, this vehicle was introduced as the Impulse in 1983. For the 1983 and 1984 model years, only one engine was available, the 2.0 L SOHC inline-four engine, rated at 90 hp (67 kW), 108 lb⋅ft (146 N⋅m). A MPFI turbocharged model was introduced in 1985, with a 2.0 L SOHC engine rated at 140 hp (104 kW) and 166 lb⋅ft (225 N⋅m). The 1987 model year had the RS model which came with a 4ZC1 turbo engine. The 1988 model year saw several changes. Mild exterior and interior changes were made to the appearance of the vehicle (including a larger rear spoiler and fixed headlights without pop up covers).

The 2.0 L non-turbo engine was replaced with a 2.3-liter version, rated at 110 hp (82 kW) and 127 lb⋅ft (172 N⋅m) of torque. The 2.3 L engine was offered only in the US market, because the larger engine would have obligated Japanese consumers to pay more annual road tax, thereby affecting sales, as well as the larger engine conflicted with Japanese government regulations concerning maximum displacement for cars classified as "compact". All Impulses received a Lotus-tuned suspension beginning in the 1988 model year, which consisted of redesigned sway bars, stiffer dampers, and a change in previous spring rates.

In the US market, the Impulse was marketed as "everything standard", meaning that all Impulses came with all available equipment for the vehicle's model year, and only two trim levels offered: non-turbo and Turbo. There were, however, some special edition models, most notably the RS model of the 1987 model year, available only in white body color with pewter color trim, and featuring the stiffest suspension available on any Impulse, very close to the Irmscher suspension sold only in Japan. For the 1989 model year, a Special Edition non-turbo model was offered which was equipped with the Turbo model wheels and interior trim.

The vehicle was sold as the Piazza in Europe and Australia, though introduced into these markets in 1985 or later.

In the UK the Piazza was sold in only one trim level and only Turbo form, with a 147 bhp 2.0 Turbocharged engine (4ZC1-T).

The Piazza had a shaky start in the UK with the first importer Isuzu GB, based in Maidstone, Kent going out of business in 1986, and London car dealer Alan Day bought the remaining stock of Piazzas at a bargain price. These cars were sold by Alan Day at significantly reduced price; the main reason Isuzu GB went out of business was due to high unit price. In 1987 International Motors Group of West Bromwich (IM Group) were awarded the official Isuzu franchise for the UK. (They also at the time represented Subaru and Hyundai in the UK.) IM Group still marketed the Piazza in single trim/engine form, but they only sold the updated 'Lotus' Piazza. The earlier cars sold by Day became known as 'pre-Lotus' cars; the suspension and handling of these pre-Lotus cars was derided by UK Press as poor, especially the live axle arrangement at the rear, which by the late '80s was seen to be antiquated. The updated 'Handling by Lotus' car was available from 1987 and the handling, although keeping the live axle arrangement, was transformed by Lotus in the UK after significant development work, involving modified suspension layouts, larger brakes, specially produced dampers and Goodyear tyres. The 'Handling by Lotus' cars had updated interior and exterior equipment. The exterior having a redesigned rear, with a large 'hoop' spoiler, new rear lamps, new rear badging with 'Handling by Lotus' badges and removal of the rubber side bumper strakes for a cleaner, more modern look. The updated interior trim was mainly 'tweed' check fabric, an updated centre console, but the loss of air conditioning to keep the price down for the UK market.

The Piazza was marketed in Australia as the YB series Holden Piazza.

Isuzu (UK) Ltd, the West Bromwich-based importer, sold the Lotus Piazza from 1987 to 1989, before concentrating on the 4WD Isuzu Trooper. They never sold the second generation Piazza in the UK, nor was it sold in any European market.

In Australia , the Piazza was introduced very late (April 1986), and offered only in Turbo form. It was badged as a Holden Piazza. The first generation Piazza was replaced by the Opel Vectra-based Holden Calibra in Australia.

Performance of the Turbo model was comparable to the Mitsubishi Starion/Dodge Conquest, as demonstrated by the fact that the acceleration and handling numbers reported by the auto enthusiast magazines were within 0.1–0.2 seconds between the vehicles.

In the US, the Impulse was replaced by the second generation Impulse after the end of the 1989 model year. However, in Japan, the first generation Piazza continued production and was available through the 1991 model year.

Second generation (JT22; 1990)

Second generation (JT22)
Overview
Also called	Asüna Sunfire (Canada) Isuzu Impulse (North America)
Production	1990–1993
Body and chassis
Body style	3-door liftback coupé 3-door station wagon
Layout	Front engine, front-wheel drive / four-wheel drive
Related	Isuzu Gemini/Stylus Geo Storm Isuzu PA Nero
Powertrain
Engine	1.6 L 4XE1 DOHC I4 (US, Canada only) 1.6 L 4XE1W turbo DOHC I4 1.8 L 4XF1 DOHC I4
Transmission	5-speed manual
Dimensions
Wheelbase	2,451 mm (96.5 in)
Length	Base: 4,168 mm (164.1 in) 4,216 mm (166.0 in)
Width	1,694 mm (66.7 in)
Height	Base: 1,313 mm (51.7 in) 1,298 mm (51.1 in)

Isuzu Impulse RS Turbo, rear view

The second generation Piazza/Impulse was designed on General Motors's second generation R-body "world car" platform. GM had commissioned Isuzu to build a replacement for the Spectrum, this time including a sportier model called the Storm (Gemini Coupé in Japan). The body design of the Storm was strongly influenced by GM and drew heavily from GM Europe's design submission for the Lotus Elan M100. Under Shiro Nakamura, Isuzu's then head of design, the third generation Gemini sedan was first designed on this platform, and then attention was turned to a sporty coupé to replace the first generation Impulse. Starting with the Storm, alternative front and rear treatments were made, retaining the "capsule" theme of the Gemini sedan, and drawing heavy influence from the rear-wheel drive Impulse (semi-concealed headlights with integrated grille as well as hood and taillight styling) while also expanding on the "European look", which later became a central point of marketing the vehicle in Japan.

In the United States, the three-door hatchback debuted as the Impulse XS in 1989 for the 1990 model year. It was offered only in front-wheel drive with a DOHC 1.6 L (1588 cc) inline-four engine which produced 130 hp (97 kW) and 102 lb·ft (138 Nm). The suspension consisted of MacPherson struts both front and rear, with a rigid trailing arm front suspension and a multi-link rear suspension, featuring Nishiboric passive steering. Because of labor shortages in Japan, however, the car was only ready for press introductions in March 1990 and went on sale shortly thereafter.

For the 1991 model year, the Impulse RS was introduced with a 160 hp (119 kW) and 150 lb·ft (203 Nm) turbocharged engine and all-wheel drive drivetrain which featured rear viscous differential and center planetary differential and viscous coupling. The wagonback model was also introduced for the 1991 model year, only available with the normally aspirated 1.6 L engine.

For the 1992 model year, the Turbo model was discontinued and the base engine was replaced with a 1.8 L (1809 cc) engine, sharing the same bore but with a longer stroke due to the taller engine block. This larger powerplant was good for 140 hp (104 kW) and 125 lb·ft (169 Nm). Both body styles continued into 1992, but very few were produced.

The second generation Impulse was produced in very low numbers, totaling slightly over 13,000 units, with that number including the production of the Isuzu Stylus. General Motors, who owned nearly half of Isuzu, also owned Lotus Cars at the time. Lotus selected the 1.6-litre engine and transmission from the Isuzu Gemini for the Lotus Elan M100 and a following generation of that engine eventually ended up in the Impulse. Lotus was subcontracted by Isuzu to fine-tune the suspension of the Impulse, through selection of stiffer dampers, larger sway bars, and softer springs. All of the second generation Impulses had the Lotus-tuned suspension.

A non-Lotus innovation in the Impulse was the development of the Nishiboric passive rear-wheel steering system which adjusted the toe of the rear wheels by changing the rear wheel alignment through the range of suspension travel.

The combination of the burst of the Japanese economic bubble, rising emissions and crash safety requirements, and continued restrictive market segment changes by General Motors forced Isuzu out of the car making market and brought an end to the Impulse.

In the Japanese market, this vehicle was sold as the Piazza from July 1991 through the spring of 1992. The second generation Piazza was offered only in front-wheel drive with the 1.8 L engine. All of the second generation Piazzas came with the Lotus-tuned suspension. The Japanese were also offered the Geo Storm version of the Piazza, called the Piazza PA-Nero. This model was exclusive to the Japanese import dealership network Yanase Co., Ltd., under a special arrangement that sold GM products in Japan.

In Canada , the same models, with minor variations, were sold in the 1990 and 1991 model years. No Impulses were made for Canada for the 1992 model year. In 1993 the 1.8 L model was sold in Canada as the Asüna Sunfire, but only with the hatchback body. With the phaseout of the Asüna brand in 1993, the Sunfire name moved to a Pontiac, as its version of the third-generation Chevrolet Cavalier on the GM J platform rather than an Isuzu platform.

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  1991 Isuzu Impulse RS interior showcasing the "space capsule" design theme

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  1993 Asüna Sunfire

External links

• IsuzuPiazza.com— Isuzu Piazza Online Community
• Isuzu Piazza Turbo Owners' Club (IPTOC) (Great Britain)