Volvo’s foray into twincharged engines, a sophisticated system combining both supercharging and turbocharging, represented a unique approach to optimizing engine performance. This complex engineering aimed to harness the low-end responsiveness of a supercharger while leveraging the high-speed efficiency of a turbocharger, theoretically eliminating the drawbacks of each individual system. However, this intricate setup, once a hallmark of Volvo’s innovative powertrain strategy, has largely been phased out, particularly in the updated XC90 Plug-in Hybrid (PHEV) model. The decision to remove the supercharger from the T8 PHEV powertrain was driven by a desire for simplification and improved integration with Volvo’s evolving hybrid technology. Combining supercharging and turbocharging offered theoretical advantages, but the practical execution presented challenges that Volvo ultimately sought to overcome through a more streamlined approach.
The XC90 T8 PHEV’s Powertrain Evolution
The previous iteration of the XC90 T8 PHEV featured a highly complex powertrain that included a turbocharger, a supercharger, and an electric motor. This intricate system was further complicated by the integration of a larger battery pack and a revised rear e-axle introduced in 2021. According to Stefan Molen, Volvo’s Department Program Manager for Hybrid Powertrains, the decision to remove the supercharger was a strategic move towards simplifying the powertrain. “It was a very complex solution to combine hybrid with a turbo and a supercharger, and with the new hybrid system, it was an opportunity to simplify the powertrain,” Molen explained.
This complexity was not without its drawbacks. During real-world driving, particularly in fluctuating traffic conditions, the powertrain could become confused. Accelerating to a point where the supercharger would hand off power to the turbocharger, only to ease off the throttle during this transition, often led to hesitation from the 8-speed automatic transmission. The gearbox would struggle to select an optimal gear, sometimes resulting in the turbocharger operating just off its boost threshold or the supercharger nearing the end of its effective range. The disconnect between the three primary systems—the engine, the turbo/supercharger configuration, and the rear electric motor—often led to a lack of seamless coordination, detracting from the overall driving refinement.
Embracing Turbocharging and Electrification
With the supercharger now absent from the XC90 lineup, Volvo has opted for a more conventional approach, relying solely on turbocharging across its engine variants, including the B6 derivative which still features the twincharged engine. When questioned about the potential adoption of electric turbochargers, a technology employed by other manufacturers like Porsche and Mercedes, Molen reiterated Volvo’s commitment to avoiding unnecessary complexity and cost. “Again, that adds complexity and cost, and we want to avoid unnecessary complexity,” he stated. The current XC90 lineup, with its focus on comfort and safety rather than outright sportiness, does not necessitate such advanced solutions.
Similarly, Volvo has chosen not to implement its PowerPulse technology, which utilizes a compressed air tank to rapidly spool up the turbocharger, in the XC90’s gasoline engines. While PowerPulse was available on certain foreign-market diesel models and demonstrated a noticeable improvement in responsiveness, Molen explained that the rear electric motor in the T8 PHEV effectively mitigates turbo lag. “On the T8, the e-motor on the rear axle compensates when the turbo isn’t fully spooled, so you never get that feeling of lag,” Molen said. “So we don’t feel it’s necessary to complicate the system when the exhaust gas turbocharger works perfectly as is.” This pragmatic approach aligns with Volvo’s brand ethos, which prioritizes a comfortable and secure driving experience. Volvo XC90 Among Four EVs And Hybrids With New Names .
The Shifting Landscape of Volvo’s Powertrains
Volvo’s initial commitment to an all-electric lineup by 2030 has recently been adjusted, reflecting a broader market shift with decreased demand for electric vehicles. While the long-term goal remains electrification, internal combustion engines are likely to persist beyond 2030. The current strategy emphasizes powertrain simplicity, but future advancements will undoubtedly be influenced by increasingly stringent emissions regulations globally. The upcoming Euro 7 legislation in Europe and emission bans in certain US states by 2035 present a significant challenge for automakers. Volvo faces the delicate task of ensuring its gasoline engines comply with these regulations without incurring substantial investment in powertrains with a limited lifespan. This complex situation, mirrored across the automotive industry, is expected to drive innovation, though the specific path Volvo will take—whether through radical innovation or a more conservative approach—remains to be seen. Volvo XC90 Generations: Everything You Need To Know In One Place .
The elimination of the twincharged engine from the XC90 T8 PHEV signifies a move towards a more streamlined and integrated powertrain strategy. By prioritizing simplicity and leveraging the capabilities of its electric motors, Volvo aims to deliver a more refined and efficient driving experience, even as it navigates the evolving landscape of automotive technology and environmental regulations. Volvo Has The Best New Car Deal No One Is Talking About .
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