Mid-engine, four-wheel-drive layout
In
It is a type of car
The centre differential contained within many 4 wheel drive cars is similar to the conventional differential in a 2-wheel drive car. It allows torque to be distributed to both drive axles whilst allowing them to spin at different speeds, which vastly improves the cornering of a 4-wheel drive car on surfaces with high grip such as tarmac. However, unlike the differentials on the drive axles which are configured to provide torque equally to both wheels, the centre differential is usually set to have a bias to one set of drive wheels or the other, depending on application of the car.
Some 4 wheel drive cars use a centre viscous coupling unit that will provide most power to the rear wheels unless the amount of torque being supplied to the rear wheels is in excess of the traction limits of the rear tyres, such as in a Lamborghini Murciélago.[1] Others contain a computer that will decide how much power to distribute to any wheel at any time depending on the circumstances of each wheel. In general the M4 system is not widely used[citation needed] as it is suited toward sports cars and some off-road racing vehicles.
Benefits
The engine is usually where the weight of a car is most concentrated so placing it between the front and rear axles gives a car a much better
A computer-controlled four-wheel-drive differential system allows a car to both accelerate and corner more quickly, since it can vary the amount of torque going to the front and rear wheels, and therefore vary how much the car behaves like a
Drawbacks
Some cars are designed with a rear wheel drive powertrain where the power is sent to the rear wheels. This design is cheaper than the M4 design because of the limited parts required to make the system function. Manufacturers use a unique layout to balance the weight distributed between the front and rear axels. Having a front engine layout with a rear wheel drive powertrain almost evens out the weight distributed in order to optimize performance and handling.
Most mid-engine cars, because of the size and position of the engine and transmission, compromise heavily on both passenger and
Four-wheel-drive systems tend to be quite heavy and some of the engine's power can be lost through the various differentials in the car, in addition to the frictional losses of the powertrain.
The variable handling characteristics of a four-wheel-drive car mean that when travelling round a corner at high speeds the car may enter the corner and understeer and then half-way through the corner suddenly start to oversteer.[4]
Gallery
-
Peugeot 205 T16, the first of the M4 Group B rally cars
-
Lamborghini Diablo VT6.0, an early M4 supercar
-
Bugatti Veyron, the world's fastest production car at the time of its production
-
petrol-electricdrive for the front wheels
-
Ferrari SF90 Stradale, a twin-turbocharged PHEV M4
References
- ^ "Lamborghini Murcielago - Car Cutaway - Modern Racer - Features".
- ^ "Stop and weight! A 50/50 weight distribution is not optimal | Automotive Thinker - Discussing the finer points of automobiles".
- ^ "Series 8 Episode 5". Top Gear. BBC. BBC Two. 2006-06-04.
- ^ RallyCars.com Full time 4 wheel drive turbo charged car dynamics