Monday, October 22, 2007

Layout

The drive train and engine layout determine the handling characteristics of an automobile, and is the point of the design of a sports car.

The front-engine, rear-wheel drive train layout (FR layout) is common to sports cars of any era. This configuration has survived longer in sports cars than in mainstream automobiles. Current examples include the Caterham 7, Mazda MX-5, and the Chevrolet Corvette.

In search of improved handling and weight distribution, other formats have been tried. The RMR layout is commonly found only in sports cars — the motor is centre-mounted in the chassis (closer to and behind the driver), and powers only the rear wheels. High-performance sports car and supercar manufacturers, such as Ferrari and Lamborghini prefer this layout. Many modern cars, especially grand tourers, also use a FMR layout, with the motor sitting between the front axle and the firewall.

2005 Leopard 6 Liter Roadster, a classic sport-style front-engine, rear-wheel drive (FR) layout
2005 Leopard 6 Liter Roadster, a classic sport-style front-engine, rear-wheel drive (FR) layout

Porsche is one of the few, remaining manufacturers using the rear-engine, rear-wheel drive layout (RR layout). The motor's distributed weight across the wheels, in a Porsche 911, provides excellent traction, but is not ideal, as the engine's weight is not between the two axles; the vehicle is poorly balanced, thus, many early Porsches handled twitchily. Yet, Porsche have continuously refined the design and, in recent years, combined engineering modifications and electronic driving aids (i.e. computerised traction-stability control) to counteract inherent design shortcomings.

1990s Lotus Elan; a front-engine, front wheel (FF) drive sports car
1990s Lotus Elan; a front-engine, front wheel (FF) drive sports car

Some sport cars have used the front-engine, front-wheel drive layout (FF), e.g. Lotus Elan M100, Fiat Coupé, Fiat Barchetta, Saab Sonett, Toyota Celica and many Berkeley cars. This layout is advantageous for small, light, lower power sports cars, as it avoids the extra weight, increased transmission power loss, and packaging problems of a long driveshaft and longitudinal engine of FR vehicles. Yet, its conservative handling effect, particularly understeer, and the fact that many drivers believe FR is a more appropriate layout for a sports car make this layout atypical to high-performance sports cars. The FF layout, however, is common in sport compacts and hot hatches, such as the Honda Civic Si/Type R and the Volkswagen Golf GTi, which are not necessarily sports cars.

Before the 1980s few sports cars used four-wheel drive, which had traditionally added a lot of weight. Not a sports car, but the Audi Quattro, with coaxial driveshafts, proved its worth in rallying, and with the added advantage of all-weather traction ability. Four-wheel drive is now common in high-powered sports cars, including Porsche, Lamborghini, and the Bugatti Veyron (currently holds the world speed record for 407 km/h (253 mph) supercar.

0 Comments:

Post a Comment

Subscribe to Post Comments [Atom]

<< Home