The evolution of the turbo system- The new RX-7 is equipped with a radically new Sequential Twin Turbo. The rotary engine does not have any reciprocating parts and is thus inherently smooth at high speeds. Our challenge, however, was to improve torque in the low- to medium-speed range, allowing the driver more controllability in any driving conditions. The easiest way to maximize torque in the low- to medium-speed range is to increase engine displacement. The four-rotor engine in the 787B is an example. However, we did not take this approach for the new Rx-7 because our development theme called for extensive weight reduction. Instead, our choice was to upgrade the turbo system. The exhaust characteristics of the rotary are ideal for turbo-chargers because the exhaust pulse much stronger than a piston engine. Our target was to develop a turbo system that maintains the high-speed nature of the rotary engine while providing enormous amounts of low-end torque. Conventional single turbo systems are effective to achieve high power at high engine revolutions, but usually with less power at low speed. In contrast, our new Sequential Twin Turbo system is effective over a much wider engine speed range. The Sequential Twin Turbo system optimizes the forced induction effect throughout the speed range by operating one turbo at low revs and both turbo's at high speed. Only the primary turbo is activated at low speed, enabling it to respond more quickly and effectively, while at high speed, both turbo's function, resulting in a smooth delivery op power. At low speed, the exhaust passage that leads to the secondary turbo is closed by a valve, thus, only the primary turbo is operating. As the engine speed and load rise and the exhaust gas volume increases, a portion of the gas is directed towards the secondary turbo via a pre-spinning control valve to prepare it for full operation. Various parameters such as engine load, throttle opening and atmospheric pressure are calculated by a computer, which then determines the optimum moment to open the switching valve, thus allowing the secondary turbo to start providing full boost. Tuning this pulsation by optimizing the length of the inlet tracts forces an optimum amount of fuel/air mixture into the combustion chambers.The new High-Speed, Speed-Density Electronic Gasoline Injection system was developed in order to reduce the intake resistance and improve the engine response throughout the rev range. It does mot use the mechanical airflow meter, instead an electronically controlled unit within the surge tank directly measures intake pressure, accelerating the Dynamic Forced Induction effect, and making extremely precise fuel management possible.The air-to-air intercooler is directly exposed to cold air from the front, an efficient layout that results in a compact design 0.4kg lighter than the previous model. The intake ducts are made of plastic for a weight saving of approximately 1kg. This turbo arrangement enables the engine to respond briskly throughout the rev range and delivers exhilarating acceleration.The engine is also equipped with the Dynamic Forced Induction system. The instant-taneous opening and closing of the rotary's inlet and exhaust ports generates strong intake pulsations A single, stainless-steel silencer, which a lower exhaust gas resistance, replaces from the former dual type, reducing the weight of the entire exhaust system by 8kg. The razor-sharp pick-up, resulting from around 90% of torque being developed at only 2500rpm, the immediate willingness to rev through the redline with the rotary's trademark smoothness, and the seemingly endless acceleration in each gear, all provide an exhilarating challenge for the driver. The rotary power of the new engine is always ready to respond faithfully to the commands of the driver's right foot.