The Turbo Unveiled

A Closer Look at Technology and Performance

Introduction

As you know, WOT embodies a passion for performance and innovation. At the heart of this approach lies the turbocharger, a device that harnesses exhaust gas energy to increase the intake air density and, consequently, engine power. This article traces the history of the turbo, details its operation, and explores the main variants—from fixed geometry models to advanced systems like variable turbo, twin-scroll, bi-turbo, and e-turbo—while explaining why this technology is a true performance lever for WOT.

The History of the Turbo

The turbo story begins in the early 20th century with the ingenuity of Alfred Büchi, a Swiss engineer who envisioned using the energy in exhaust gases to compress the air entering the engine. Initially developed to compensate for reduced air density at high altitudes in aircraft engines, this innovation quickly spread to the maritime and automotive sectors. Büchi’s idea sparked a technological revolution that enabled significant power gains while optimizing energy efficiency.

How a Turbo Works

The basic principle of a turbocharger relies on two essential elements connected by a common shaft. On one side, the turbine, driven by exhaust gases, captures a portion of the lost energy and converts it into rotational movement. On the other side, the compressor, powered by the same shaft, draws in and compresses ambient air before injecting it into the engine. This process of forced induction increases the amount of air in the cylinders, thereby improving combustion and power output. By optimizing air density, the turbo enhances performance without requiring a larger engine displacement, a feature especially valued in the context of downsizing and efficiency pursuits.

The Different Types of Turbo

Fixed Geometry Turbo
The fixed geometry turbo is the most traditional model. Its design relies on a turbine whose configuration does not change, offering a simple and proven solution. While this approach already provides a notable power increase, it requires a compromise between responsiveness and maximum capacity, which sometimes limits its adaptability to different driving conditions.

Variable Geometry Turbo (VGT/VNT)

To meet the demands of increasingly dynamic driving, engineers developed the variable geometry turbo. This system integrates movable vanes in the turbine housing that adjust according to the engine speed. By adapting in this way, the variable turbo reduces the infamous “turbo lag” and provides optimal response at both low and high speeds. Initially reserved for diesel engines, this technology is now found in high-end gasoline engines. The Porsche 911 Turbo (997) was the first production model to benefit from variable geometry turbochargers, developed in collaboration with BorgWarner.

Twin-Scroll Turbo

The twin-scroll turbo stands out for its ability to better utilize exhaust pulses. By separating gases from specific cylinder groups using a dual-entry design, this system optimizes spool-up and provides a more even power curve. The distinct management of the exhaust flow significantly improves engine responsiveness, a feature particularly sought after by sports car enthusiasts.

Bi-Turbo, Tri-Turbo

There are several approaches to multi-turbocharging, ranging from the classic bi-turbo to the electrically assisted tri-turbo, each offering specific advantages in terms of performance and responsiveness.

The parallel bi-turbo is the simplest: each turbo feeds a separate bank of cylinders, improving responsiveness by using smaller, lighter turbochargers. This configuration is common on V engines, such as those in the BMW M5, Audi RS6, or E63 AMG.

The sequential bi-turbo, on the other hand, optimizes power delivery by activating a small turbo at low RPMs to reduce “turbo lag” before a larger one takes over at higher RPMs. This system provides a smooth and efficient power boost across the entire rev range. Models like the Toyota Supra 2JZ-GTE and Porsche 959 were among the first to use this technology.

The tri-turbo, notably used by BMW on its M50d, goes even further by integrating a third electric compressor. This eliminates any lag at low RPMs before transitioning to two conventional turbos. This approach ensures immediate responsiveness and consistent power while improving fuel efficiency.

A fun fact: at BMW, word choice is strategic and can lead to confusion. On the engine cover, the “TwinPower Turbo” label might suggest an engine with two turbochargers. In reality, this term refers to a single twin-scroll turbo, optimized to improve responsiveness and torque. In contrast, when an engine genuinely has two turbos, BMW uses the term “TwinTurbo Power,” a subtle but essential distinction between these configurations.

E-Turbo (Electrically Assisted Turbo)

The e-turbo is a major evolution in turbochargers, integrating an electric motor to eliminate turbo lag and optimize boost pressure from low RPMs. Unlike traditional turbos, which rely solely on exhaust gases, the e-turbo uses electricity to spin the turbine instantly, ensuring immediate responsiveness and linear power delivery. In addition to improving responsiveness, this technology enhances fuel efficiency by reducing consumption and extending component lifespan. Though relatively new, this technology has already been adopted by several leading models. Mercedes-AMG was one of the first manufacturers to incorporate it into its 2.0L turbo engine for the AMG C43 and C63, developed in collaboration with Garrett.

Conclusion

Unlike naturally aspirated engines, whose optimization potential is limited, turbocharged engines offer a wide range of improvements through precise management of boost pressure via engine mapping and mechanical tolerances.

At WOT, we maximize every engine’s potential by tailoring our reprogramming to the specific characteristics of each vehicle. Whether for more dynamic driving or performance-oriented tuning, our approach ensures controlled power increases, optimizing both responsiveness, torque, and fuel efficiency, all while preserving component reliability and adhering to current emission standards.