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The highlight of the engine is a two-stage boost, consisting of a supercharger with a mechanical drive and a turbocharger. The unit is offered in two versions: 140 hp and 220 N.m of torque or 170 hp and 240 N.m. The difference in return is provided exclusively by the firmware of the control unit, the mechanical part is unchanged.
Up to 2400 rpm, only a mechanical compressor works: the exhaust speed is too low to spin the turbine unit. In the range of 2400–3500 rpm, he works with effective returns, however, with sharp acceleration, a mechanic still helps him, covering up the inevitable turboyama. After 3500 rpm, the inlet control flap is fully open and directs the entire volume of air to the turbocharger. As a result, a weaker engine reaches its maximum torque from one and a half thousand revolutions, and a 170-strong engine is 250 rpm higher. By the way, an interesting function is sewn up in the control unit of a more powerful unit: the driver can activate the winter driving mode with the key even with a manual gearbox. The engine in this case works softer, minimizing wheel slippage.
The dual-circuit cooling system has already been tested on engines of the FSI family: one circuit for the cylinder block, the other for the head. With such a scheme, it is easier to maintain the optimum operating temperature of the engine, which means lower emissions and fuel consumption. For example, to accelerate heating and reduce the likelihood of overheating in power modes, a hotter head needs to be cooled more intensively. Therefore, the volume of fluid circulating in the head is twice as large as in the block, and the thermostat (of course, there are also two of them) opens at 80 and 95 ºC, respectively. In addition, to protect the turbine from overheating, thereby prolonging its life, an auxiliary water pump with an electric drive helps, which drives the fluid along a separate circuit for 15 minutes after stopping the engine.
The engine is extremely saturated with modern technologies, which raises the unit in the eyes of technical experts. Just do not forget about the proper operation. The key to the health of this motor is good fluids and consumables and, of course, qualified and timely service. A complex combination in our conditions. And the cost of the main components and assemblies more than covers all the amounts that high technology allows to save on gasoline.
The coolant pump pulley is simultaneously the compressor magnetic clutch pulley. Both drive belts pass through it. The compressor is located on the engine side facing the passenger compartment:
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Therefore, to reduce noise, the unit was dressed in an additional case with walls of sound-absorbing foam, and the air flows entering and leaving it pass through the silencers. To develop a maximum boost pressure of 1.75 atm, a gearbox (right photo) is installed in the case of the mechanical compressor, which increases the rotation speed by five times, up to 17, 500 rpm.
The cylinder block is made of cast iron:
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Despite the general struggle with extra pounds, there is no worthy replacement for this material for turbo engines with a high degree of forcing. The so-called open block (there are no jumpers between the block walls and the cylinder wells) provides better cooling and more uniform cylinder wear. Piston rings are easier to compensate for, which helps reduce oil consumption. But the cylinder wells are interconnected - this is a necessity for a turbo engine: with increased loads, freestanding cylinders lack rigidity in the upper zone.
The high pressure fuel pump is located on the camshaft bearing housing
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It is driven by a separate cam on the intake shaft. To increase injection pressure and increase productivity, the piston stroke was increased in the pump compared to FSI atmospheric engines.