Twin-turbo refers to a turbocharged engine on which two turbochargers compress the intake charge. There are two commonly used twin turbo configurations; parallel twin-turbo, and sequential twin-turbo. A third kind of twin-turbocharging called staged turbocharging exists, but is used more in diesel racing applications than road cars.

Parallel twin-turbo

Parallel twin-turbo refers to a turbocharger configuration in which two identical turbochargers equally split the turbocharging duties. Each turbocharger is driven by one 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. Both turbos function simultaneously, unlike sequential twin-turbos. Commonly each turbocharger is mounted to its own individual exhaust/turbo manifold, however on inline-type engines both turbochargers could be mounted to a single turbo manifold. Parallel twin turbos are usually applied to V-shaped engines where one turbo is assigned to each cylinder bank, providing packaging symmetry, and simplifying plumbing; however, it is not uncommon for a parallel set-up to be used on an inline engine. Nissan's RB26DETT is an inline-6 that uses a twin-turbo set-up, as is BMW's N54. Toyota's 1992 Supra with the 1JZ-GTE (Japan only) 6 cylinder inline engine also used this same configuration, as does Volvo's 1998-01 2.8L B6284T and 2002-06 2.9L B6294T straight-six engines in the 1998-2006 S80 T6 and 2003-05 XC90 T6, Nissan's 1990-1996 Z32 300ZX with its V6 VG30DETT. Audi's 1997-2002 S4 (B5), 1997-2004 A6, and 2003-2004 RS6 are examples of a parallel twin turbo implementation where each turbo is driven by one bank of cylinders, as the motor in each is in a V formation.

While a parallel twin-turbo set-up theoretically has less turbo lag than a single turbocharger set up, because of marginally-reduced combined inertial resistance, and often simplified exhaust plumbing, the fact that both turbos spool at more or less the same time means that there is still a noticeable bit of lag, especially in high-flow turbo/high boost applications. One way to counter this is to use a light pressure set up where the turbos are designed to output less boost but spool earlier, however, this set up sacrifices top end power. Another system would be the use of variable geometry turbochargers, this system changes the angle of the guide vanes depending on the exhaust pressure giving the system excellent power throughout the rev range. Once used mainly in turbocharged diesel engines, Porsche was the second to use it in a mass-production gasoline-powered vehicle in 2006 with the 911 Turbo (997).

Parallel operation of the turbochargers can still be used to great effect as demonstrated by the Bugatti Veyron; which runs four relatively small turbochargers in parallel.

equential twin-turbo

Sequential twin-turbo refers to a set up in which the motor can utilize only one turbocharger for lower engine speeds, and both turbochargers at higher engine speeds. During low to mid engine speeds, when available spent exhaust energy is minimal, only one turbocharger (the primary turbocharger) is active. During this period, all of the engine's exhaust energy is directed to the primary turbocharger only, lowering the boost threshold, and increasing power output at low engine speeds. Towards the end of this cycle, the secondary turbocharger is partially activated (both compressor and turbine flow) in order to pre-spool the secondary turbocharger prior to its full utilization. Once a preset engine speed or boost pressure is attained, valves controlling compressor and turbine flow through the secondary turbocharger are opened completely. At this point the engine is functioning in a full twin-turbocharger form, providing maximum power output.

Sequential twin-turbocharger systems provide a way to decrease turbo lag without compromising ultimate boost output and engine power. Examples of cars with a sequential twin-turbo setup include the 1993-1998 Toyota Supra Turbo (JZA8x), the 1992-2002 Mazda RX-7 Turbo (FD3S), the 1994-2005 JDM Subaru Legacy RS, and the 1986-1988 Porsche 959. With recent advancements in turbocharger design, sequential twin turbo systems have fallen out of favor because they are seen as unnecessarily costly and complex.

ee also

*Boost gauge
*Boost controller

External links

* [ Autozine Technical School: Twin-Turbo]

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Hennessey Viper Venom 1000 Twin Turbo — The Hennessey Viper Venom 1000 Twin Turbo is an upgraded version of the Dodge Viper offered for sale as a whole car or as an upgrade by Hennessey Performance Engineering, also known as HPE. It comes in two varients, a coupe and a convertible. It… …   Wikipedia

  • Turbo-transmission — Turbo Transmissions are hydrodynamic, multi stage drive assemblies designed for rail vehicles using combustion engines. The first turbo transmission was developed in 1932 by Voith in Heidenheim, Germany. Since then, improvements to turbo… …   Wikipedia

  • Turbo (Album) — Turbo Studioalbum von Judas Priest Veröffentlichung 15. April 1986 Label Columbia Records, Sony (Japan) …   Deutsch Wikipedia

  • Turbo (álbum) — Turbo Álbum de estudio de Judas Priest Publicación 31 de marzo de 1986 Grabación Compass Point Studios Diciembre de 1984 Enero de 1985 Género(s) …   Wikipedia Español

  • Twin Famicom — Fabricant Sharp Corporation Type Console de salon Génération Troisième Date de sortie …   Wikipédia en Français

  • Turbo-Hydramatic — Infobox Automobile name=Turbo Hydramatic production=1964– manufacturer=General Motors class=3 speed longitudinal automatic transmission predecessor=Dynaflow Hydra Matic Powerglide Jetaway Super Turbine 300 successor=4L60 E/4L65 E 4L80 E/4L85 E… …   Wikipedia

  • Turbo (Judas Priest album) — Infobox Album | Name = Turbo Type = Album Artist = Judas Priest |225px Released = April 14, 1986 Recorded = 1985 Genre = Heavy metal Length = 50:11 Label = Columbia Producer = Tom Allom Reviews = *Allmusic Rating|2.5|5… …   Wikipedia

  • Turbo (альбом) — У этого термина существуют и другие значения, см. Turbo. Turbo …   Википедия

  • Turbo Lover (song) — Infobox Single Name = Turbo Lover Artist = Judas Priest Album = Turbo B side = Released = 1986 Format = Recorded = 1985 Genre = Heavy metal Length = 5:33 Label = Columbia Records Writer = Rob Halford K. K. Downing Glenn Tipton Producer = Tom… …   Wikipedia

  • Twin Famicom — Infobox CVG system title = Twin Famicom logo = manufacturer= Sharp Corporation type= Video game console generation= Third generation (8 bit era) lifespan= JPN July 1, 1986 CPU = media= Cartridge Famicom Disk Card controllers = 2 controller ports… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.