The Story Of The "Busso" V6 Engine

The classic Alfa Romeo V6 engine, nicknamed "Busso," from his creator's name, the legendary Alfa Romeo engineer Giuseppe Busso, is so revered among enthusiasts that its presence under an Alfa's bonnet often multiplies the car's market value. In this article, I'll go through the history of this legendary powerplant.



Chapter One - Genesis

This story starts at the end of the 1960s, a time of success and confidence for Alfa Romeo. With the Alfetta and Alfa 6 already on the drawing board, it was clear a brand new engine was needed, especially for the larger saloon. The engineers wanted a compact, lightweight unit, leading to an aluminum 60° V6 engine, with a more modern and efficient cylinder head design than the classic twin-cam fours. On the new V6, the two valves per cylinder had a much tighter angle between them, to reduce thermal losses and have straighter inlet tracts. In a departure from previous Alfa Romeo practice, a single, belt-driven camshaft per cylinder bank only operated the intake valves directly, while the exhaust valves were conducted by a rocker via a short pushrod.

Although the first V6 prototypes started running on test benches by 1968, the world wouldn't get to hear Arese's violin for another decade.

The 1973 Oil Crisis took the whole automobile industry by storm, especially the small, financially weak Alfa Romeo. The flagship saloon Alfa 6 wouldn't see the light until 1979, together with the 2,5 liters V6 designed for it.


Chapter Two - Carbureted V6s 1979 - 1986

Although the choice of six Dell' Orto carburetors for the Alfa 6 engine may seem puzzling, the reason lay in the rudimentary fuel injection technology then available. No fuel injection system could yet manage individual throttle bodies. Busso and the Alfa engineers were justifiably proud of their lusty engines and did not want to compromise the throttle response and drivability they wanted.

1983 saw the introduction of two more carbureted variants of the V6 engine, whose individual purposes could not be more different.

Between 1983 and 1987, a downsized two liters version of the V6 engine was made available on the Alfa 6 saloon, in an attempt to increase its sales potential in Italy. Meanwhile, in South Africa, Alfa Romeo built a limited run of 200 GTV6, equipped with a V6 enlarged to three liters to compete in the local touring car championship.


Chapter Three - Fuel-Injected V6s 1980 - 1987

1980 sees the Busso V6 appear under the bonnet of the restyled Alfetta GT. The GTV6, thanks to the 158 HP of its fuel-injected 2.5 liters V6, soon becomes the car enthusiast's darling, with its attractive combination of style, practicality, and performance.

This version of the Busso V6 then went into the restyled Alfa 6 saloon in 1983, the newly-launched 90 in 1984, and the 75 in 1985. 1986, the last year of Alfa Romeo as an independent carmaker, saw the introduction of the 90 two liters V6, equipped with Alfa Romeo's own electronic fuel injection system, the CEM. Available exclusively on the Italian market, where only around 1500 cars were sold.


Chapter Four - 3.0 V6 1987 - 1998

Although three liters Busso V6s had been made before, this enlarged variant didn't enter mainstream production until February 1987, when the Alfa 75 3.0 V6 "America" was introduced. Meanwhile, Alfa's all-new FWD flagship, the 164, was presented later that same year, in September.

To make the Busso V6 fit under the 164's bonnet line, the Alfa Romeo engineers redesigned the intake, moving the throttle body and plenum chamber towards the firewall... And that's how those sexy, shiny inlet tracts were born! These would remain a staple of all transversely-installed Busso V6 engines, right until the end of production.

This 192 HP V6 would live on until 1998 under the "916" Spider's bonnet, while the 164 switched to the newer 24v version from 1992, the same year a detuned Busso three-liters V6 found its way under the hood of the Lancia Thema, replacing the bought-in PRV unit the model used on the model since '84.

The most powerful production version of the 12v three-liters Busso V6 was the one fitted to a very special Alfa Romeo, the SZ, presented in 1989.

The engine used on the SZ derived from the unit used on the 75, with a higher compression ratio and a sharper cam profile to boost power up to 210 HP.

At this point, we shall not forget that the three liters V6 did not spell the end of the 2.5 liters one, which returned for 1992 to power the front wheels of the newly-launched "155" saloon.


Chapter Five - V6 Turbo 1991 - 2000

Italian taxation penalized petrol engines over two liters of capacity, making the 164 V6 a forbidden fruit for many Italian Alfisti. Given over 50% of all Alfa Romeos were sold below the Alps, it's easy to see why the company presented the 164 V6 Turbo, in 1991.

While the exhaust note couldn't match the glorious wail of the 3.0 liters unit, the two liters' turbocharged cars often proved faster in real-world driving conditions. Very popular on the 164 and then on the GTV coupé, this punchy little beast of an engine was briefly offered on the 166 as well, before being discontinued upon the arrival of Euro 3 antipollution regulations.


Chapter Six - 24 Valve V6s 1992 - 2005

The most significant chapter in the Alfa Romeo V6 engine evolution has undoubtedly been the adoption of four valves per cylinder in 1992. The new cylinder heads were designed according to the latest trends in technology, with a yet narrower angle between the intake and exhaust valves for a more compact, thermally efficient combustion chamber. The four valves per cylinder were now directly operated by two belt-driven overhead camshafts per bank. Ignition cables were gone and replaced by a modern direct ignition system with a coil per each spark plug. Those spark plugs, to reduce maintenance costs, were higher-quality items with platinum inserts, expected to last 100.000 Km.

Although the unit fitted to the stunning Proteo concept car of 1991 packed a claimed 260 HP, the production engine output ranged from the 204 HP on the Lancia Kappa to the 232 seen on the 164 Quadrifoglio Verde and the later Q4.

1997 saw the debut of one of Alfa Romeo's greatest commercial successes, the stunningly beautiful 156, whose range-topping model came equipped with the sweet 2.5 liters V6 engine, which packed 190 HP thanks to the new 24 valve cylinder heads.

The Busso three-liters V6 was also briefly available on the unsuccessful Lancia Thesis, between 2001 and 2003.


The Last Hurrah

Automobile production at the historic site of Arese ended in 2000, leaving the Busso V6 production line as the last remaining activity in the old factory, a place whose fate had already been decided, around 100 Kms away in Turin, by Fiat's top brasses.

For the embattled Italian conglomerate, whose fortunes had been steadily declined over the 1990s, the Milanese V6 now was a residual program, with no future and for which no development money was going to be spent. Until the 156 GTA program gave the Alfa V6 a chance for a last hurrah, one more moment to shine before the end.

The increment in displacement was achieved through a new crankshaft with a longer stroke, while the cylinder's bore remained unchanged.

From 2003 onwards, a slightly detuned version of the 3.2 liters V6 ended up replacing the three-liters engine throughout the Alfa Romeo range, from the GTV to the 166, but also on the Lancia Thesis. However, the last model to ever be powered by a Busso V6 has been the GT coupé designed by Bertone. The final batch of engines was built on the 31st of December 2005, and, in a sad but rather fitting coincidence, Giuseppe Busso died aged 92 just a few days later, on the 3rd of January 2006.

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