Twin-turbo

Twin-turbo or biturbo refers to a turbocharged engine in which two turbochargers compress the intake charge. More specifically called "parallel twin-turbos". Other kinds of turbocharging include sequential turbocharging, and staged turbocharging. The latter is used in diesel automobile racing

Parallel twin-turbo

Paralleled twin-turbo refers to the turbocharger configuration in which two identical turbochargers function simultaneously, splitting the turbocharging duties equally. Each turbocharger is driven by half of the engine's spent exhaust energy. In most applications, the compressed air from both turbos is combined in a common intake manifold and sent to the individual cylinders. Usually, each turbocharger is mounted to its own individual exhaust/turbo manifold, but on inline-type engines both turbochargers can be mounted to a single turbo manifold. Parallel twin turbos applied to V-shaped engines are usually mounted with one turbo assigned to each cylinder bank, providing packaging symmetry and simplifying plumbing over a single turbo setup. When used on inline engines, parallel twin turbos are commonly applied with two smaller turbos, which can provide similar performance with less turbo lag than a single larger turbo. Some examples of parallel twin-turbo inline engines are Nissan's RB26DETT, BMW's N54 and Volvo's B6284T and B6294T. Some examples of V formation engines with parallel twin-turbos include Mitsubishi's 6A12TT and 6G72TT; Nissan's VG30DETT and VR38DETT; and Audi's 1997-2002 S4 (B5), 1997-2005 A6, and 2003-2004 RS6.

Twin

Twins are two offspring produced by the same pregnancy. Twins can either be monozygotic ("identical"), meaning that they can develop from just one zygote that will then split and form two embryos, or dizygotic ("fraternal"), meaning that they can develop from two different eggs; each are fertilized by separate sperm cells.

In contrast, a fetus which develops alone in the womb is called a singleton, and the general term for one offspring of a multiple birth is multiple.

Statistics

The twin birth rate in the United States rose 76% from 1980 through 2009, from 18.9 to 33.3 per 1,000 births. The Yoruba have the highest rate of twinning in the world, at 45–50 twin sets (or 90–100 twins) per 1,000 live births, possibly because of high consumption of a specific type of yam containing a natural phytoestrogen which may stimulate the ovaries to release an egg from each side.

In Central Africa there are 18–30 twin sets (or 36–60 twins) per 1,000 live births. In Latin America, South Asia, and Southeast Asia, the lowest rates are found; only 6 to 9 twin sets per 1,000 live births. North America and Europe have intermediate rates of 9 to 16 twin sets per 1,000 live births.

BBC

The British Broadcasting Corporation (BBC) is the public service broadcaster of the United Kingdom, headquartered at Broadcasting House in London.

The BBC is the world's oldest national broadcasting organisation and the largest broadcaster in the world by number of employees, with over 20,950 staff in total, of whom 16,672 are in public sector broadcasting; including part-time, flexible as well as fixed contract staff, the total number is 35,402.

The BBC is established under a Royal Charter and operates under its Agreement with the Secretary of State for Culture, Media and Sport. Its work is funded principally by an annual television licence fee which is charged to all British households, companies, and organisations using any type of equipment to receive or record live television broadcasts. The fee is set by the British Government, agreed by Parliament, and used to fund the BBC's extensive radio, TV, and online services covering the nations and regions of the UK. From 1 April 2014, it also funds the BBC World Service, launched in 1932, which provides comprehensive TV, radio, and online services in Arabic, and Persian, and broadcasts in 28 languages.

Turbocharger

A turbocharger, or turbo (colloquialism), from Greek "τύρβη" ("wake"), (also from Latin "turbo" ("spinning top"),) is a turbine-driven forced induction device that increases an internal combustion engine's efficiency and power output by forcing extra air into the combustion chamber. This improvement over a naturally aspirated engine's output results because the turbine can force more air, and proportionately more fuel, into the combustion chamber than atmospheric pressure alone.

Turbochargers were originally known as turbosuperchargers when all forced induction devices were classified as superchargers. Nowadays the term "supercharger" is usually applied only to mechanically driven forced induction devices. The key difference between a turbocharger and a conventional supercharger is that a supercharger is mechanically driven by the engine, often through a belt connected to the crankshaft, whereas a turbocharger is powered by a turbine driven by the engine's exhaust gas. Compared to a mechanically driven supercharger, turbochargers tend to be more efficient, but less responsive. Twincharger refers to an engine with both a supercharger and a turbocharger.