Race track design and technology drives the Ford Indigo concept sports car

The Ford Indigo is a high performance, V-12 concept sports car that takes its design and technology inspiration from some of the fastest cars in the world, Indy car and Formula 1 racing cars.

With over 260 Indy car triumphs — including 17 Indianapolis 500 wins — plus more than 200 Grand Prix victories and 13 constructor’s world championships in Formula 1, Ford is the most successful manufacturer in the history of Indy car and Formula 1 motor racing.

The Indigo combines Ford and primarily Indy car technologies and practices in the areas of materials, construction techniques, powertrain and aerodynamics to create a new dimension in driving excitement by bringing the thrill of the race track to the street.

But the Indigo is much more than just an exciting new show car. Two versions of the car have been produced: a non-driveable “Show” car that will tour the major international auto shows in 1996; and a fully-functional, engineered and driveable model, nicknamed the “Go” car by the Indigo team.

Monocoque chassis technology

The “Go” derivative of the Indigo features a monocoque chassis which was designed and manufactured using current Indy car build practices. The chassis was developed in conjunction with Reynard Racing Cars, the UK-based specialist supplier and winner of the 1995 CART/PPG Indy Car World Series Constructor’s Championship.

The chassis consists of a specially designed central tub formed of a lightweight carbon fiber, aluminum honeycomb composite material. This monocoque chassis differs from a conventional chassis in that it is a one-piece, highly-efficient racing-inspired structure that both forms the Indigo’s interior and has the front suspension and running gear attached to it.

The rigid construction of the chassis cocoons the driver and passenger in a cell-like structure, with the wide air intake ducts located in the deep rocker panels providing an exceptional level of side-impact protection. Many of the composite components are also being studied to examine their structural properties under stress.

Indy car suspension

The front suspension — Indy car-type double wishbones with pushrods operating inboard coil-over shock absorbers — is fitted directly to the chassis tub. The rear suspension also features double wishbones with pushrods and inboard coil-over shock absorbers and locates directly to the transaxle.

Both front and rear suspensions are formed from the same high strength, aero section chrome moly steel tubing that Reynard uses on its Indy cars. The rear suspension arms and geometry are virtually identical to those of an Indy car, while the Indigo’s two-passenger tub required the front suspension arms be shorter and have a slightly different geometry than that found on the racing cars.

And while Indy cars often require as little as one inch of suspension travel to achieve maximum handling, the Indigo has considerably more travel to cope with the demands of driving on the street.

No rubber or neoprene bushings are used in the suspension system; pivot points are all rosejoints or spherical bearings. Steering is by a modified Taurus rack-and-pinion fitted with custom-designed electric power-assist.

All-new V-12 engine

The Indigo is equipped with an all-new V-12 engine developed by the Core & Advanced Powertrain Engineering team within Ford’s Advanced Vehicle Technology group, the organization responsible for generating new technologies for future production vehicles.

The V-12 is a 6.0-liter, four-cam, 48-valve, 60 degree engine which currently has an output of 435 hp (SAE net) at 6,100 rpm and 405 lbs-ft torque at 5,250 rpm. The engine is still undergoing development testing, but these are the expected final horsepower/torque levels when the engine is tuned to meet current and future projected emissions levels running through catalysts fitted to the stainless steel exhaust system.

As powerful as the engine is, one of its main features is the abundance of low-end torque. Approximately three-quarters of the V-12′s maximum torque is available at just 1,000 rpm. The engine is also notable for its fuel efficiency and is expected to achieve over 28 mpg in normal highway driving.

The V-12 represents not only a very powerful engine but also a breakthrough in development cost and timing. This is largely the result of the unit’s clever use of existing Ford engine components.

The basis for the V-12 is the current production 3.0-liter Duratec V-6 engine used in the 1996 Ford Taurus and Mercury Sable. It uses the same bore and stroke dimensions (89.0 mm x 79.5 mm) as the Duratec, and also shares its pistons, rings, rods, valves, valve seals, valve springs and retainers.

However, the V-12 block and cylinder heads are all-new, cast from 356-T6 aluminum alloy by Cosworth in Great Britain. The cylinder heads retain the Duratec’s combustion chamber and exhaust port design. The intake ports incorporate a new, “tumble-port” design that creates low-rpm, intake-charge turbulence without the need for throttling one of each pair of intake valves.

Unlike the Duratec, the V-12 block is not a girdled design. Instead, it is deep-skirted for extra torsional stiffness. (The V-12 approximates the torsional rigidity of the Duratec V-6 despite its extra length.) The crankshaft is formed using an all-new casting process called “electro-slag casting”, which is claimed to result in crankshafts that are 10 percent stronger than forged units.

Several other revisions were made to the Duratec design to adapt components to the new V-12 configuration. These include a new water pump, extra internal cooling passages and oil-spray jets that cool the underside of the pistons to add an extra measure of thermal control for sustained high-rpm driving, such as autobahn runs.

Dual spray fuel injectors — single injectors for each cylinder that spray both intake ports at the same time — are used in the V-12 and are similar to the components utilized in the last production Taurus SHO V-6 engine. Fuel is fed to the engine via pumps housed in the racing-style, bladder fuel cell. A dry sump system is also fitted to the engine to ensure consistent oil flow through the block.

Cooling is provided by twin 14 x 14-inch radiators, one each side of the passenger compartment, with air being force-fed through the large side air scoops behind the front tires. Additional cooling in low-speed driving is available from electric fans.

The V-12 is perfectly balanced to minimize noise, vibration and harshness (NVH). Included in its second-generation onboard diagnostic system (OBD II), is a flame ionization sensor which detects in-cylinder misfire.

The engine is also bolted rigidly to the chassis’ passenger compartment rear bulkhead and also acts as a load-bearing member — standard practice on Indy cars.

The development of the V-12 began prior to the Indigo project and took just 18 months from inception until the first engine was tested on a dyno in September 1995.

Racing-derived transaxle

The Indigo utilizes a longitudinally-mounted, modified Reynard Indy car transaxle. This unit has six forward gears and a reverse, and features a racing-style, manually-operated carbon clutch. The forward gears are selected sequentially by a an electronic, hydraulic shifter.

Buttons on the front of the Nardi steering wheel signal the system to upshift, while alternate buttons on the back of the wheel control downshifts. The clutch must be used on all shifts.

Massive wheels and tires 

The V-12′s power reaches the ground via the Indy car-style Fikse three-piece modular wheels. Wheel sizes are 11.5 x 17-inch front and 12.5 x 18-inch rear, and have a five-bolt pattern instead of the more usual racing single center-lock design. (The five-bolt pattern is considered to be safer for street use as wheel-to-hub positioning is more consistent when the wheels are installed by someone other than a fully-trained pit crewman.)

The massive wheels are wrapped in special hand-cut Goodyear Eagle high performance racing tires, correlating to street-tire sizes of 335/30ZR-17 on the front and 355/35ZR-18 at the rear.

Brembo 335 x 20 mm front and 355 x 20 mm rear disc brakes help to stop the Indigo in an estimated 100 feet in computer simulated 60 to 0 mph testing.

Exhilarating yet functional design

Functionality and the racing car theme were strong influences in the design of the body. In keeping with Indy car practice, the Indigo’s exterior body panels consist of composite carbon fiber and aluminum honeycomb. Just as on racing cars, some of the panels are retained in their black composite carbon fiber finish to contrast with the bright red of the remaining body panels.

The scissor-style doors are hinged at the front and are raised by lifting them forward and slightly out from the body, allowing the driver and passenger to step down into the car.

The car has undergone wind tunnel testing. The results show that enough downforce is being generated by the wings, underbody diffuser and overall body shape to enable the Indigo to corner at a projected lateral acceleration of 1.2g.

The ability to see the road clearly at night or in low light conditions is an essential safety feature for any car. The Indigo has an advanced lighting system developed with Philips Lighting. It uses a high-intensity discharge (HID) light source, with light piped through fiber optics to the main headlamps which are uniquely situated in the front section of the door rear view mirrors.

Additional HID fog lights and turn signals are located in the front wing, which also acts as a bumper. The rear taillights, consisting of small projector lights, are located at the outboard edges of the rear wing.

Interior continues Indy car theme

The interior of the Indigo is geared towards creating the racing car experience for the road. It consists of a black carbon fiber finish with some elements trimmed in black leather.

An electronic, Indy car-style instrument cluster features gauges for engine rpm, gear position, a speedometer and engine temperature. A premium stereo radio with a mini disc changer are positioned in the center of the instrument panel.

The leather-trimmed, power-operated, deep bucket seats jointly designed with Johnson Controls include four-point harnesses, with the lap belts integrated into the seat base. Usually, a four-point racing belt system would comprise of four separate belts which lock into a central buckle.

However, this semi-integrated restraint system is divided into a left and right side belt — each side containing two of the four belts — with just one connection into the buckle for greater ease of use.

The interior also has provision for the fitment of driver and passenger airbags.

The building of the Indigo — which took just six months to complete from the first computer design rendering to a driveable car — was primarily the responsibility of Ford’s Advanced Design team and Advanced Vehicle Technology group, suppliers Reynard Racing Cars and ASC, with Ford’s New Concepts Organization overseeing the management of the project. Many other Ford suppliers were also involved in the construction of the car.

The New Concepts Organization is a group within Ford Product Development that fosters fresh ideas on niche and “breakthrough” vehicle concepts and also assists in developing low-cost vehicle designs and production processes.