<P> Sequential turbocharger systems provide a way to decrease turbo lag without compromising ultimate boost output and engine power . Perhaps the most noteworthy application of this system is the fourth - generation Toyota Supra (1993 - 1998), which is generally regarded as having the most reliable sequential turbo system yet fitted to a production automobile, with a reported failure rate of less than 1% as of 2011 . Other examples of cars with a sequential twin - turbo setup include the 1986 - 1988 Porsche 959, the 1990 - 1995 Eunos Cosmo JC, 1992 - 2002 Mazda RX - 7 FD3S Turbo (13B - REW engine), the 1994 - 2005 JDM Subaru Legacy GT, GT - B & B4 RSK (EJ20TT engine), and the Peugeot 407 2.2 HDi . GM has filed a patent for a sequential twin - turbo system that uses a new bypass valve design said to optimize exhaust flow to the turbines of both turbochargers . According to the 2016 patent description, the exhaust manifold features two outlets with one directing exhaust gases to the turbine of the high - pressure turbocharger, while the second exhaust manifold outlet directs exhaust gases to the turbine of the low - pressure turbocharger via a connecting channel . Additionally, exhaust gas exiting the high - pressure turbine is directed to the inlet of the low - pressure turbine . The new bypass system features two throttle valves located on the same spindle mounted perpendicular to each other . With the throttle valves mounted on the same plane, one valve opens to direct exhaust gas flow to one of the turbochargers while the other valves simultaneously blocks exhaust gas flow to the other turbocharger . The vehicle ECU (electronic control unit) sends a signal to the spindle's actuator to rotate the throttle valves based on rpm and load . GM says the new design allows engineers to optimize exhaust gas flow to both turbines without the compromises of traditional sequential turbocharger systems . Additionally, the system could utilize a variable - geometry turbine or a fixed - geometry turbine on the high - pressure turbo . </P> <P> A sequential turbo can also be of use to a system where the output pressure must be greater than can be provided by a single turbo, commonly called a staged twin turbo system . In this case, multiple similarly sized turbochargers are used in sequence, but both operate constantly . The first turbo boosts pressure as much as possible (for example to three times the intake pressure). Subsequent turbos take the charge from the previous stage and compress it further (for example to an additional three times intake pressure, for a total boost of nine times atmospheric pressure). This configuration is commonly found on piston engine aircraft which usually do not need to rapidly raise and lower engine speed (and thus where turbo lag is not a primary design consideration), and where the intake pressure is quite low due to low atmospheric pressure at altitude, requiring a very high pressure ratio . High - performance diesel engines also sometimes use this configuration, since diesel engines do not suffer from pre-ignition issues and can use significantly higher boost pressure than Otto cycle engines . </P> <P> While spark ignition engines have fallen out of favor of the sequential turbo design, many diesel companies now make engines with sequential turbos in order to reduce emissions . </P>

Is twinpower turbo the same as twin turbo