More than any other component, the engines defined the personality of the Alfa Romeo 166. The range
offered was a reflection of the brand's rich engineering tradition, providing options that ranged from
technological efficiency to pure visceral emotion.
The Legendary "Busso" V6
At the core of the 166 experience was the iconic "Busso" V6 engine, an engineering masterpiece designed by
Giuseppe Busso. This engine was revered not only for its robust performance, but for being a true piece of
mechanical art. With its chromed and polished intake manifolds, it was an engine as beautiful to look at as
it was to listen to. Its sound, especially at high revs, was a metallic, guttural, and melodic symphony,
frequently compared to an Italian opera, which became the soul of the car for many enthusiasts.
In the 166, the Busso was available in three gasoline variants:
- 2.5 V6 24V: The entry point into Alfa's world of six cylinders, offering a
balance between performance and smoothness.
- 3.0 V6 24V: The main engine, which equipped the top versions and was the
only option offered in Brazil. With up to 226 hp, it provided vigorous performance and transformed the
166 into an authentic grand tourer.
- 2.0 V6 12V Turbo: A version with lower displacement but with a
turbocharger, created primarily for the Italian market to bypass tax legislation that penalized engines
over 2.0 liters. Despite its reduced size, it delivered 205 hp and impressive torque at low revs.
The production of the last Busso engine, on December 31, 2005, marked the end of an era for Alfa
Romeo. In a tragic coincidence, its creator, Giuseppe Busso, passed away just a few days later, on January
3, 2006.
Twin Spark (TS) Technology
The entry-level engine was the 2.0 Twin Spark 16V, an inline four-cylinder that carried the legacy of
Alfa's famous bialbero (twin-cam) engines. Its technology was sophisticated, employing two spark plugs per
cylinder, a phase variator on the camshaft, and a variable geometry intake manifold. These features aimed to
optimize fuel combustion across the entire rev range, resulting in an engine with good torque at low revs
and eager to rev high.
Despite being a technically advanced engine praised for its liveliness, many critics and owners
considered its 155 hp only adequate to move the 166's more than 1,400 kg. To extract truly sporty
performance, it was necessary to keep the engine at high revs, which impacted fuel consumption.
Additionally, the timing belt of this engine became a well-known weak point, requiring preventive changes at
shorter intervals than recommended by the factory to avoid catastrophic failures.
The Pioneering 2.4 JTD
For the European market, where diesel engines were gaining increasing importance, Alfa Romeo equipped
the 166 with the 2.4 JTD inline-five engine. This powertrain was one of the pioneers in the use of
second-generation common-rail technology, which allowed for more precise and efficient fuel injection. The
result was a notably refined diesel engine for its time, with low levels of noise and vibration, and a
generous torque of over 300 Nm available from low revs, making it ideal for long highway journeys.
The choice of engine, however, implied a fundamental compromise in the driving experience. The heavy
Busso V6, mounted transversely over the front axle, gave the car a tendency to understeer when pushed to the
limit in corners. Furthermore, its power and torque, unleashed on the front wheels, resulted in noticeable
torque steer, the sensation of the steering wheel "pulling" to one side during hard acceleration. In
contrast, the 2.0 Twin Spark engine, being significantly lighter, relieved the weight on the front axle.
This resulted in a more agile car, with more neutral and communicative steering, truer to Alfa Romeo's ideal
of dynamic balance. The buyer was therefore forced into a choice that defined the personality of their car:
the soul, sound, and performance of the V6, sacrificing a bit of handling purity, or the agility and balance
of the Twin Spark, giving up the power and unparalleled charisma of the Busso.