What is the T-Hybrid?

T-Hybrid is Porsche’s lightweight and powerful hybrid system developed for sports cars. It consists a 3.6-litre engine, an electric exhaust turbocharger (eTurbo), a compact and lightweight high-voltage drive battery and a strengthened eight-speed dual clutch transmission (PDK) with an integrated electric motor.

What is the T-Hybrid?

The centrepiece of the T-Hybrid is the new 3.6-litre six-cylinder boxer engine with an electric turbocharger. The electric motor drastically shortens the time required for the turbo to spool up. Because of this, the full boost pressure is consistently available within a very short time. This ensures that the 3.6-litre boxer engine maintains the ideal air-fuel mixture ratio and still builds up torque quickly. Even at an engine speed of 1500 rpm, a system torque output of 500 Nm is produced. The full torque of 610 Nm is even available from less than 2000 rpm.

The eTurbo is designed so that the integrated electric motor can both deliver torque to the turbocharger shaft and generate electrical power from its rotation. As a generator, it produces up to 11 kW of electrical power. It uses this energy to feed the electric motor in the Porsche dual clutch transmission (PDK) or to charge the high-voltage battery.

The innovative system regulates the boost pressure automatically using the generator function of the electric motor. So it doesn’t need a wastegate to limit the pressure. As the electric motor performs the functions of the alternator, and the air conditioning compressor is powered electrically, the engine doesn’t have a belt drive. This creates space above the engine to install a pulse inverter and DC-DC converter.

New PDK Transmission

Porsche developed also a new PDK specifically for the T-Hybrid. It is based on the gearbox from the previous models but differs in several important aspects. The clutches, gear sets and bevel-gear drive are designed to be stronger in order to cope with the significant increase in system torque. Furthermore, a taller final-drive ratio reduces the engine speed, especially at high road speeds.

A permanently excited synchronous motor is fully integrated into the gearbox housing. It fits into the existing gearbox oil cooling system and is coupled directly to the crankshaft via the dual-mass flywheel. The compact module measures just 286 mm in diameter and 55 mm in length. Nevertheless, it delivers a drive torque of 150 Nm from idling speed and provides a power output of up to 40 kW (54 PS). In generator mode, it can feed up to 40 kW to the high-voltage battery. The electric motor also performs the tasks of the starter and alternator, thereby saving weight.

Compact and Lightweight High-Voltage Battery

The T-Hybrid system is based on a compact and lightweight high-voltage battery. It combines an operating voltage of 400 volts and a gross capacity of 1.9 kWh with a compact design. Its weight (about 27 kg) and dimensions correspond to those of a conventional 12-volt AGM starter battery. For reasons of weight distribution, it is located in the front, under the bonnet in the new 911 Carrera GTS.

The 12-volt starter battery for the T-Hybrid drivetrain was specially developed for use in the performance hybrid system. With an energy capacity of 40 Ah, the lightweight lithium iron phosphate battery (LiFePO₄) measures just 90 mm in height and weighs seven kilograms. A standard 70 Ah lead-acid starter battery is around three times heavier. The lightweight battery offers high-voltage stability, better charge acceptance, high cycle stability and a long service life.

In combination with its components, the performance hybrid system achieves greater driving performance with optimised CO₂ emissions and low additional weight. The overall weight increase is only 50 kg.

Images by Porsche