The Swansong of Hybrid Vehicles… or Maybe Not. The Advent of Electric Turbochargers

Disclaimer: First, I love electric vehicles and the direction the automotive industry is heading towards. It’s just that I am not entirely sure if skipping hybrid vehicles to accelerate the transition to EV is a good idea, for both producers and consumers. Second, this is a fairly lengthy piece of reading, and even though I am not an engineer by training, it does unearth a lot of domain knowledge surrounding the latest automotive technology, so I hope readers can stick around!

Introduction

Many people have called plug-in hybrid vehicles (PHEV) transitional products that serve to fill the temporary void between the phase-out of internal combustion engine vehicles (ICE) and the introduction of electric vehicles (EV). Now that we see an increase in manufacturers following the footstep of Elon Musk’s Tesla Motor and launching more pure EV products, such as the Audi e-tron GT, Porsche Taycan, and Hyundai IONIQ 5, one question surfaces: Are PHEVs obsolete?

To be fair, before making a case for why PHEVs might be a mainstay in the automotive industry for longer than most would initially guess, PHEVs do have their fair share of problems, the most significant one being the added complexity in their architecture. Unlike ICE vehicles, which require a gasoline power unit and a gearbox connected to a drive shaft that ultimately delivers power to an axle (already quite complicated and requires careful maintenance), PHEVs also have the added complexity of integrating an electric power unit in their powertrain. The electric power unit in its simplest form requires four components: the electric motor, the gearbox, the battery, and the inverter. To package all these components under one vehicle architecture is no small task, and PHEVs are often faulted for driving R&D costs high and being a maintenance nightmare.

A Case for Hybrids

However, I would like to make a case for PHEVs and go on to say they might be combining the best of both worlds, housing the most sophisticated gasoline engine the industry can produce and the nexus of electric powertrain in a platform that blends the best of the past and the hope for the future.

Allow me to break down my hypothesis into two parts. First, gasoline-powered vehicles have been in existence since Carl Benz’s creation in 1885. In other words, the technology behind ICEs is very mature and today’s gasoline engines can take some serious beating without showing any significant signs of fade. In fact, the new W206 C63 would be equipped with the M139 four-cylinder engine and pack enough gobsmacking performance with unquestionable reliability.

Second, there are not a lot of convincing reasons to buy the EVs today. Don’t get me wrong, the future of EV is bright, with attractive propositions such as better efficiency and instantaneous torque. But the EV technology is still in its infancy and we could expect exponential growth in foreseeable decades, which means if you are buying an EV today, even if it is the $2.3M Lotus Evija with around 2,000hp, the technology you are buying would be equivalent to a carriage drawn by a horse by tomorrow. In short, buying a fully electric car is like buying a piece of the imaginary future, where the actual future might exceed the expectations by a large margin.

Icing on the Cake: A Crash Course on Forced Induction

Now that a baseline for hybrids has been established, allow me to zero in on a topic most car aficionados would be familiar with - forced induction (aka “more power baby”). In the past, manufacturers’ go-to method to increase a gasoline engine’s power has always been to expand the displacement, as exemplified by the iconic American muscle cars from the1960s. With increasingly stringent pollution standards and the awakened environmental consciousness, manufacturers have to move on to forced induction methods to satisfy the hunger of speed-obsessed folks.

The recipe to make big power is simple: air, fuel, and ignition. Since the goal is to maximize power and minimize emissions, the variable that modern manufacturers tinker with is the air volume being fed into the combustion chamber. To force more air into the engine, manufacturers have historically used supercharger and turbocharger to achieve more effective combustion cycles.

Supercharger works by using the power generated by the engine to drive a belt. The belt will spin and create needed motion in the compressor, which would then compress and channel the air into the combustion chamber. This method has been utilized on cars like the Dodge Challenger Hellcat and the Mercedes SLR McLaren to greatly improve the power output. However, despite the naturally aspirated-like throttle response, the supercharger has a contradictory problem: it takes away power to create more power.

Turbocharger is a prevalent piece of technology in the automotive world that circumvents the problem of supercharger. A turbocharger works by first cooling the air entering through an intercooler. Through liquid cooling and heat exchange principle (making the temperature difference between the inlet air and the cylinder as big as possible to produce more energy), the intake air will be condensed by the spooling turbo and be ready for more explosive combustion. A key benefit of turbocharger is that the spooling of turbo is done through redirecting the exhaust gas, which is a form of recycling wasted energy.

But despite its merits, turbocharger’s biggest drawback is turbo lag, referring to the lag in between spooling up and achieving full boost pressure. In the past, manufacturers and car tuners have tried to overcome the lag by either having a twin turbo setup (offset sizing so the small turbo will spool up quicker for low-end power delivery and the big turbo will pick up later in higher power band) or an anti-lag system (deliberate backfiring when the gas pedal is let off to create enough back pressure to keep the turbo spooling). Both methods work to varying degrees of success, but now car manufacturers and automotive part suppliers have developed a revolutionary innovation - electric turbocharger.

Boosting Up Hybrids

Electric turbocharger comes in two forms. The first one is an electrically-assisted turbo, also called an e-booster. An e-booster works by pairing a small output electric motor connected to the compressor. When the turbocharger is taking its time to spool, the void in the power band is fulfilled with the e-booster’s burst of electric power, eliminating any hints of turbo lag. The upcoming W206 C63 is rumored to be the first production vehicle to be equipped with a commercialized version of this technology. The downside is the constraint on the size of the compressor, as it is inherently hampered by the size of the tiny electric motor regulating it. As such, a larger compressor and turbine cannot be fitted, which leaves e-booster as a solution with a caveat.

The second type of electric turbocharger addresses the downfall of the e-booster. Garett Motion, an American company renowned for producing quality turbochargers, has developed the e-turbo. The e-turbo does not just pair an electric motor to a turbocharger; instead, it directly incorporates the electric motor into the turbocharger in one unit. This offers a distinct advantage of rapidly spooling the turbo at lower rpm or in instances of weak gas flow. Since the e-motor is built-in to the turbocharger, the size of the compressor and turbine is no longer restricted, which makes it a more clever design for producing big power.

In the end, the advent of electric turbocharger, disregarding the two types, is going to transform how manufacturers use turbocharged gasoline engines. The instant electric power delivery not only ensures that turbo lag will be completely eliminated, but also introduces the possibility of building gasoline motors with even smaller displacement and larger turbocharger; a combination destined for better fuel efficiency and improved performance. In addition, PHEVs equipped with electric turbochargers are going to outperform EVs in a very important way. Electric motors have a very aggressive power delivery that plateaus early, but lacks the verve when spinning at high speeds. This drop in performance can be addressed when the system is integrated with a heavily turbocharged gasoline engine. While the electric motor supplies the abundant torque to move the car, the gasoline power unit with electric turbocharging can provide incredible horsepower to make sure the car has enough oomph to go faster.

Conclusion

Hybrids may not be the ultimate answer for the future of the automotive industry, but thanks to electric turbocharger and the myriad of benefits this technology provides, I believe hybrids are here to stay for the foreseeable future, at least until EV powertrain makes another leap of progress. The EURO 7 emissions standard is coming into effect in 2025, and if consumers want to access excellent automobiles that find a balance between outright performance and eco-friendliness, then hybrids are truly the best of both worlds.