1979-2005 Alfa Romeo DOHC V6
Alfa Romeo’s in-house V6 engine design made its initial debut in 1979 in the Alfa 6 as a hybrid SOHC/pushrod design. Introduced in 2.5 Liter guise, production engines would eventually range from 2.0 Liter to 3.2 Liter displacement. With modification, it is possible to increase this engine’s displacement to 3.8 Liters (232 cu in).
Initially developed in the early 1970s by Giuseppe Busso, the original SOHC 12-valve design employed short push-rods to operate the exhaust valves in a design similar to that of earlier BMW/Bristol engines. In 1993, the first DOHC version of this engine appeared powering the Alfa Romeo 164.
Currently, the engine has aluminium alloy block, cylinder head and oil sump and exhaust valves are are filled with sodium to avoid overheating.
Engine Family:
1979-1989 2.5 Liter Two Valve –
The 2.5L began as a longitudinal installation in GTV6. The engine displaced 2.5 Liters (2,492 cc (152.1 cu in) and produced 156 HP. It was a 2-valve-per-cylinder design with a single belt-driven camshaft per cylinder bank and 6 single throat carburettors fitted.
Fuel injection was added for the 1983 Alfa 6, which produced the same 156 HP. The 2-valve engine ended its life in the Alfa 155, where there were two series, both developing 164 HP, with only small differences between them.
Applications:
- 1979-1986 Alfa Romeo Alfa 6
- 1980-1986 Alfa Romeo GTV6
- 1984-1987 Alfa Romeo 90
- 1985-1991 Alfa Romeo 75/Milano
- 1992-1997 Alfa Romeo 155
- 1985-1996 Fiat Croma
- 1987-1989 Rayton Fissore Magnum V6
1997-2007 2.5L Four Valve –
A four-valve DOHC-version of the 2.5 was introduced in 1997 with the Alfa Romeo 156. In this configuration, the engine produced 187 HP. In 2001, the V6 was uprated to 189 HP. The Alfa 166 used a slightly detuned version to make more low-end torque. The engine has a 88 mm (3.5 in) bore and a 68.3 mm (2.69 in) stroke.
This engine version was awarded as the International Engine of the Year in 2000.
Applications:
1985-2003 3.0L Two Valve –
The 2.5 L engine was bored and stroked to 3.0 L by Alfa racing in South Africa, in 1985 (2,959 cc- or 180.6 cu in) it was quite successful and th eFactory used it for the 1987 75/Milano Verde, where it produced 182 HP. At this point, it still used 2 valves per cylinder.
This engine block was modified for transverse placement in the Alfa 164 and fitted with a high-performance camshaft and low-restriction exhaust, producing 189 HP in standard form and 181 HP when an exhaust catalyst was fitted.- The “Cloverleaf” (racing) version produced 197 HP. The same engine fitted to the 1989-1991 Alfa Romeo SZ was tuned to produce 207 HP.
The engine has a 93 mm (3.7 in) bore and a 72.6 mm (2.86 in) stroke.
Applications:
1992-2005 3.0L Four Valve –
The two valve-engine was upgraded to dual overhead cams and four valves per cylinder in 1993. Due to this and other refinements, this engine produced 208 HP for the regular 1993 Alfa 164. The Alfa 164 QV had even more punch with- 227 HP and 204 ft lbs of torque.
The “Euro 3” engine produced even more go, with 229 HP on the Q4 model. In the Alfa Q4’s final production run in 1996, the 3.0 was reduced tpo 225 HP, but with increased torque. The final run of 3.0 V6 engines fitted to the Alfa GTV and 166 produced 217 HP. The engine ceased production in 2005.
Applications:
2002-2006 3.2L Four Valve –
In 2002, Alfa Romeo introduced the 156 GTA with a 3.2 L (194.0 cu in) version of the V6. The engine produced 247 HP and 220 ft lbs of torque. This engine was also used in the Alfa Romeo 166, GTV, Spider and Alfa Romeo GT in a slightly detuned form 237 HP. The engine has a 93 mm (3.7 in) bore and a 78 mm (3.1 in) stroke.
The V6 production ended in 2005 at Alfa Romeo Arese Plant. Five thousand were built, to be used in Lancia Thesis, Alfa 166 and Alfa GT models.
The British engineering company Cosworth was keen to buy assembly tooling for the original V6 engine, but Alfa Romeo refused to sell it. This last version of Alfa block/heads 3.2 L engine was Euro4 compliant, so it would have been possible to continue to produce it a few more years. Ironically, the engine designer Giuseppe Busso died only days after the last complete engine was produced in Arese.-
The engine was replaced in the Alfa 159 and Brera by a new 3.2 L V6 unit – built by combining a General Motors-designed engine block with Alfa Romeo cylinder heads and induction.
Applications:
Alfa Romeo DOHC V6 Image 1
The V6 went through many configurations – here is shown the 3.0 Four Valve unit.
Alfa Romeo DOHC V6 Image 2
The original engine displaced 2.5L nd was longitudinally mounted. Note the small single-throat carbs for each cylinder.
Alfa Romeo DOHC V6 Image 3
Later, the engine would be transversely mounted – and eventually reach 3.0 liters, while still utilizing a two-valve cylinder head.
Alfa Romeo DOHC V6 Image 4
The engine was very sturdy and was also offered in turbocharged form. (Arrow points to the turbocharger).
Alfa Romeo DOHC V6 Image 5
The two-valve head used a SOHC setup, but only the intake was actuated directly. (1) the cam actuated a horizontal lifter (2) a pushrod went across the head to (3) a rocker arm that actuated the exhaust.
