Ukupno prikaza stranice

srijeda, 8. veljače 2012.

Car tuning

Car tuning is a generalized term to refer to the act of improving the performance or appearance of a vehicle. For actual "tuning" in the sense of automobiles or vehicles, see engine tuning. As most vehicles leave the factory set up for average driver expectations and average conditions, tuning has become a way to personalize the characteristics of the vehicle to the owner's preference. For example, cars may be altered to provide better fuel economy, produce more power, or to provide better handling.
Car tuning is related to auto racing, although most performance cars never compete. Rather, they are built for the pleasure of owning and driving such a vehicle. Exterior modifications include changing the aerodynamic characteristics of the vehicle via side skirts, front and rear bumpers, spoilers, splitters, air vents and light weight wheels.



In the 1970s and 80s, many Japanese performance cars were never exported outside the Japanese domestic market. In the late 1980s and early 1990s, grey imports of Japanese performance cars, such as the Nissan Skyline , began to be privately imported into Western Europe and North America. In the United States, this was in direct contrast to the domestic car production around the same time, where there was a very small performance aftermarket for domestic compact and economy cars; the focus was instead on sporty cars such as the Ford Mustang and Chevrolet Corvette, or on classic muscle cars.
Because of their light weight and the increasing availability of low-cost tuning equipment, economy and compact cars exhibit high performance at a low cost in comparison to dedicated sports cars. As professional sporting and racing with such vehicles increased, so did recreational use of these vehicles. Drivers with little or no automotive, mechanical, or racing experience would modify their vehicles to emulate the more impressive versions of racing vehicles, with mixed results.



Engine tuning

Engine tuning is a significant element of car tuning. An experienced engine tuner can improve the output of stock motors with the simple adjustment of values in the vehicle's engine control or powertrain control module.
Although installing a supercharger or turbo may be mistaken for tuning, this is incorrect. Tuning is necessary after installation, but the two are only interrelated in that sense, no further. Installing a forced induction system to a vehicle is more related to the act of bolting on.
Some tuners will install devices which modify communications to the Engine Control Unit in order to obtain more power. Such devices provide the stock ECU with inaccurate data from sensors to modify engine output. This is often an inexpensive way to modify an OEM computer system used to tune lightly modified vehicles. This method is known as piggy-backing, or using the stock engine management along with a chip to provide the "inaccurate" data to fool the ECU into providing the correct amount of fuel and spark timing.
Today’s car and light truck engines are fully electronically controlled. That makes it very easy to enhance the performance of the engine through “Chip-Tuning”. This refers to modifying the programming of the computer chips which control the engine management. Chip tuning can be used for both gasoline and diesel engines that are equipped with an electronic motor management.
Other standalone engine management systems are available. These systems replace the factory computer with one that is user programmable. Using such a device a tuner can control all running aspects of an engine; reducing knock, correcting air fuel ratios, and advancing or retarding timing to 
obtain efficient power levels for their setup.



Suspension tuning

Suspension tuning involves modifying the springs, shock absorbers, swaybars, and other related components of a vehicle. Shorter springs offer greater stiffness and a lower center of gravity at the cost of proper suspension geometry. Stiffer shock absorbers improve the dynamic weight shifting during cornering and normally have shorter internals to stop them from bottoming out when shorter springs are used. Stiffer sway bars reduce body roll during cornering, thus improving the grip that the tires have on the surface by reducing suspension geometry changes caused by roll; this also improves handling response due to faster weight shifting (similar to stiffer springs.) The danger with overly stiff swaybars is the lifing of the inner wheel, which reduces its traction. Loss of traction less likely with softer bars. Other components that are sometimes added are strut bars, which improve the body stiffness and help better maintain the proper suspension geometry during cornering. On some cars certain braces, anti-roll bars, etc., can be retrofitted to base model cars from sports models.
For offroad vehicles, the emphasis is on lengthening the suspension travel and installing larger tires to increase ground clearance.
These suspension modifications are in contrast to Lowriders with hydraulic or pneumatic suspensions. Lowriders use another type of suspension tuning in which the height of each individual wheel can be rapidly adjusted by a system of rams which, in some cases, makes it possible to "bounce" the wheels completely clear of the ground.

Body tuning

Body tuning involves adding or modifying spoilers and a body kit in order to improve the aerodynamic performance of a vehicle. Through the generation of downforce, cornering speeds and tire adhesion can be improved, often at the expense of increased drag. To lighten the vehicle, bodywork components such as hoods and rear view mirrors may be replaced with lighter weight components.
Often, body modifications are done mainly to improve a vehicle's appearance, as in the case of non-functioning scoops, spoilers, wide arches or other aesthetic modification. Aftermarket spoilers or body kits rarely improve a car's performance. The majority, in fact, add weight and increase the drag coefficient of the vehicle, thus reducing its overall performance.
Increasing the wheel track width through spacers and wide body kits enhance the cars cornering ability. Lowering the center of gravity via suspension modifications is another aim of body tuning. Often, suspension tuners unfamiliar with spring dynamics will cut stock springs, producing a soft, bouncy ride. It is also common to lower the car too far beyond the optimal center of gravity purely for appearance.
Competition cars may have light weight windows, or the windows may be completely removed, as auto glass adds significant weight. Plastic windows are much more vulnerable to scratches which reduces service life.

 

 


 

 



utorak, 7. veljače 2012.

Bugatti Veyron - Super car

The Bugatti Veyron EB 16.4 is a mid-engined grand touring car. The Super Sport version is the fastest road-legal production car in the world, with a top speed of 431 km/h (268 mph). The original version has a top speed of 408.00 km/h (253.52 mph). It was named Car of the Decade (2000–2009).
Designed and developed by Volkswagen Group (based on the Bentley Hunaudieres concept) and produced by Bugatti Automobiles SAS at their headquarters in Château Saint Jean in Molsheim (Alsace, France), the Veyron's chief designer was Hartmut Warkuss, and the exterior was designed by Jozef Kabaň of Volkswagen, with much of the engineering work being conducted under the guidance of former Peterbilt Trucks engineer and now Bugatti Engineering chief Wolfgang Schreiber. Though commissioned by Volkswagen, this car is only sold through the Bugatti manufacturers and cannot be found at any Volkswagen dealer.

Bugatti Veyron 16.4 Engine


The Veyron features an 8.0 litre, quad-turbocharged, W16 cylinder engine, equivalent to two narrow-angle V8 engines . Each cylinder has four valves for a total of sixty four, but the narrow staggered V8 configuration allows two overhead camshafts to drive two banks of cylinders so only four camshafts are needed. The engine is fed by four turbochargers and displaces 7,993 cubic centimetres (487.8 cu in), with a square 86 by 86 mm (3.4 by 3.4 in) bore and stroke.
The transmission is a dual-clutch direct-shift gearbox computer-controlled automatic with seven gear ratios, with magnesium paddles behind the steering wheel and a shift time of less than 150 milliseconds, built by Ricardo of England rather than Borg-Warner, who designed the six speed DSG used in the mainstream Volkswagen Group marques. The Veyron can be driven in either semi- or fully automatic mode. A replacement transmission for the Veyron costs just over US$120,000. It also has permanent four wheel drive using the Haldex Traction system. It uses special Michelin PAX run-flat tyres, designed specifically to accommodate the Veyron's top speed, which cost US$25,000 per set. The tyres can be removed from the rims only in France, a service which costs US$70,000. Curb weight is 1,888 kilograms (4,162 lb). This gives the car a power-to-weight ratio, according to Volkswagen Group's figures, of 446.3 metric horsepower (328 kW; 440 bhp) per ton.
The car's wheelbase is 2,710 mm (106.7 in). Overall length is 4,462 mm (175.7 in), width 1,998 mm (78.7 in) and height 1,204 mm (47.4 in). The Bugatti Veyron has a total of ten radiators:
  • 3 heat exchangers for the air-to-liquid intercoolers.
  • 3 engine radiators.
  • 1 for the air conditioning system.
  • 1 transmission oil radiator.
  • 1 differential oil radiator.
  • 1 engine oil radiator.
It has a drag coefficient of 0.41 (normal condition) and 0.36 (after lowering to the ground),and a frontal area of 2.07 square metres (22.3 sq ft).This gives it a drag area – the combination of drag coefficient and frontal area, represented as CdA – of 0.74 m2 (8.0 sq ft).


The Veyron Super Sport features an engine power increase from the standard 1,001 metric horsepower (736 kW; 987 bhp) to 1,200 metric horsepower (883 kW; 1,184 bhp) and torque of 1,500 N·m (1,100 ft·lbf) and a revised aerodynamic package. It was shown publicly for the first time at the Pebble Beach Concours d'Elegance in August 2010.
Bugatti's official test driver Pierre Henri Raphanel drove the Super Sport version of the Veyron on Volkswagen's Ehra-Lessien high-speed test track to establish the car's top speed. With representatives of the Guinness Book of Records and German Technical Inspection Agency (TÜV) on hand, Raphanel made passes around the big oval in both directions achieving an average maximum speed of 431.072 km/h (267.856 mph). Once produced for sale, the first five Super Sports will sport the same black and orange finish as the first production car, which was used to set the speed record, and all production models will be electronically limited to 415 km/h (258 mph) to protect the tyres.
Improved aerodynamics kit, 1,200 metric horsepower (883 kW; 1,184 bhp) 1,500 newton metres (1,100 ft·lbf) torque engine upgrade. It has a 431.072 km/h (267.856 mph) top speed, making it the fastest road car in production, although it is electronically limited to 415.07 km/h (257.91 mph) to protect the tyres from disintegrating. The first five of an unannounced production run made its debut in a matte black and orange colour combination, all of which have been spoken for. The public debut was at the Pebble Beach Concours d'Elegance in August 2010. It is valued at GB£1.7 million and Bugatti have stated that only 30 will be produced.






ponedjeljak, 6. veljače 2012.

Big buildings


The term "skyscraper" was coined in the 1880s, shortly after the first tall buildings were constructed in the United States -- but the history of tall buildings dates back hundreds of years. Since the Middle Ages, engineers have engaged in a battle for the sky. 
Before there were skyscrapers, there were towers.
Made of heavy stone, towers had thick, sturdy walls, but the rooms were dark and cramped -- too many windows would have weakened the structure.


Soon Gothic cathedrals joined the quest for height.
Long, stone arms, called flying buttresses, supported the cathedral's heavy weight, allowing the walls to be filled with colorful glass windows.
With steel came the first modern skyscrapers.
During the Industrial Revolution, engineers began experimenting with two new materials -- iron and steel. The 10-story Home Insurance Building in Chicago was the first tall building to be supported by a steel skeleton of vertical columns and horizontal beams. But even with windows, the closely spaced columns and deep beams made rooms in the Home Insurance Building feel tight and cramped.
In 1857, the installation of the first passenger elevator in the Haughwout Department Store in New York City made it possible and practical to construct buildings more than four or five stories tall.



New structural designs made skyscrapers even lighter and stiffer.
As skyscrapers grew taller and taller, engineers were faced with a new enemy: wind. Today's tallest skyscrapers, which are almost 1,500 feet tall, must be 50 times stronger against wind than the typical 200-foot buildings of the 1940s.  
Today, the sky's the limit!
As architects and engineers experiment with new styles and building methods, taller and more innovative structures are springing up around the world. The tallest buildings in the world, the Petronas Towers in Malaysia, are connected by a flexible skybridge on the 42nd floor -- a design that improves the circulation of people between the towers and provides an escape route from one tower to the other in case of emergency.