Alfa Romeo 690T engine

The Alfa Romeo 690T is a twin-turbocharged, direct injected, 90° V6 petrol engine designed and produced by Alfa Romeo since 2015.^[2] It is used in the high-performance Giulia Quadrifoglio and Stelvio Quadrifoglio models and is manufactured at the Alfa Romeo Termoli engine plant.^[6]

In May 2013, FCA CEO Sergio Marchionne brought engineer Gianluca Pivetti from Ferrari^[a] to develop a new engine for the upcoming Alfa Romeo Giulia Quadrifoglio, a flagship car meant to relaunch the brand. Pivetti along with Giorgio platform chief Philippe Krief and a team of a dozen engineers began development in Modena in July. Given a short three year deadline, the team gained technical approval of the engine within a year and a half. It then moved into development with the FCA engine plant in Termoli^[6][8] and was production ready in 2015.^[2]

The 690T is often considered to be the Ferrari F154 engine with two fewer cylinders, but in fact it is a completely new engine developed by the same engineer, Pivetti. Nevertheless, Alfa adopted similar known geometries, technologies, and materials they knew worked well to reduce development time.^[8]

The engine was created as part of the larger Giorgio project, which arose from the need to give Alfa Romeo its own new and specific architecture, designed and produced entirely in Italy, in keeping with the brand's original character.^[9] An important design requirement was the deactivation of one cylinder bank in order to satisfy efficiency goals along with performance, as its application was to be broader than only super sports cars.^[2]

Pivetti likened its uneven firing 90-degree V6 configuration to Formula 1 engines,^[b] and examples in the company's past, including the 1996 Alfa Romeo 155 V6 TI's 690 engine,^[7] and V6 engines used in the Maserati Merak, Biturbo, and Ghibli II.^[2]

With their sights set on the Nürburgring lap record for a sedan, Alfa Romeo projected the Giulia needed around 338 kW (460 PS; 454 hp). As development progressed, that power target was set higher until it reached its final form of 375 kW (510 PS; 503 hp).^[2]

When it was released, the engine was noteworthy as having more power than its contemporary rival, the BMW M3.^[11] In terms of sound, Alfa Romeo targeted the engine note of the Busso V6 in the 147 GTA and 156 GTA, working with the intake and compensating with the exhaust.^[12] Evo magazine noted, "the turbo V6 isn’t yowlingly sonorous, but it sounds throatily aggressive and much more characterful than BMW’s M3".^[7] Power delivery was meant to be progressive and engaging for the driver.^[12] Top Gear host Chris Harris said, “in terms of a turbocharged motor that really goes at the top end, this might be the best one I’ve ever driven”.^[11]

The maintenance plan calls for an accessory drive belt replacement at 4 years or 60,000 km (36,000 mi),^[13] which requires removing the bumper to gain access, but may be done more simply.^[14][15]

Alfa Romeo added port injection to comply with Euro 6d emissions regulations. Alfa plans to continue production of the engine, though it is unsure if it can be made compliant with Euro 7.^[16]

Alfa Romeo Termoli plant manufactures the engine,^[6] producing 39,833 units from 2015 to 2024.^[c] Investment for production of the 2.0 and 2.9L engines was over 1.5 billion euros.^[18]

The 690T is a V6 engine with a 90 degree cylinder bank angle, 86.5 mm (3.41 in) bore, 82.0 mm (3.23 in) stroke,^[d] a displacement of 2.9 L (2,891 cc), and two single-scroll turbochargers. In its standard configuration, it produces 375 kW (510 PS; 503 hp) at 6,500 rpm and 600 N⋅m (443 lb⋅ft) of torque at 2,500-5,400 rpm.

The crankshaft has three non-split crankpins 120 degrees apart, each with two connecting rods mounted side by side. This allows the engine to be shorter, while the 90 degree bank angle gives it a lower center of gravity.^[19] The engine is designed as two independent 3-cylinder engines mated to a common crank, with each cylinder bank having its own engine controller, intake, and turbocharger to allow for cylinder bank deactivation.^[8]

This configuration results in uneven firing at 90 and 150 degrees of rotation,^[20] but for each cylinder bank results in even firing every 240 degrees, providing evenly-spaced exhaust pulses to each turbocharger and allows one bank to deactivate.^[2] The firing order is 1-6-3-4-5-2.^[21] The odd-firing interval gives the engine a unique sound.^[20] It has a harmonic order of 1.5, half of a typical even-firing V6^[22] and the same as an inline-three, so that during cylinder deactivation, no difference in vibration can be discerned. Alfa Romeo found it unnecessary to use a balance shaft or active engine mounts to filter engine imbalances.^[2] A viscous torsional damper is mounted on the crankshaft.^[23]

The closed-deck engine block and cylinder heads are aluminum, and made by Mazzucconi in Bergamo, Italy,^[24] using low pressure die casting and tilt casting, respectively.^[25][26] For increased rigidity, the bearing caps and the lower crankcase are cast from aluminum in one piece as a bedplate and joined to the upper crankcase by 16 bolts. The oil pan is also made of aluminum. Borrowing a technique from motorcycles and Ferrari engines,^[e] the lower crankcase and oil pan are separated by three reed valves which scavenge the oil vapor from the crankcase to create a low pressure area under the pistons.^[2] This gains 30 hp (22 kW) by the reduction of pumping losses.^[28]

The pistons are made of cast aluminum with graphite coating and run in wet steel cylinder liners.^[29] The sliding surfaces of the cylinder liners are coated with silicon carbide, which limits blow-by and reduces oil consumption. The connecting rods are forged steel. The crankshaft is made of vanadium-alloyed steel and is forged from a 9 kg (20 lb) blank. It is then hardened by gas nitriding, as is done by Ferrari.^[2] The main bearings are an aluminum alloy with bismuth and silver.^[2][30]

The valvetrain has four overhead camshafts (DOHC) driven by two timing chains, one for each cylinder bank. The four valves per cylinder are actuated by roller rocker arms supported by hydraulic lifters. The intake valves are hollow and the exhaust valves are sodium-filled.^[31] Variable valve timing is accomplished by hydraulically phasing the intake and exhaust camshafts.^[32]

The right cylinder bank has collapsible hydraulic tappets to shut the intake and exhaust valves during cylinder deactivation. A solenoid valve interrupts oil flow to the stationary turbocharger, as otherwise oil would leak through the dynamic seals into the exhaust.^[8][33] Cylinder deactivation increases fuel economy by seven percent by the reduction of pumping losses.^[2] The system activates when deemed beneficial for fuel efficiency at certain speeds and torque levels.^[34]

The engine has water-cooled single-scroll^[f] parallel twin-turbochargers made by IHI, integrated into the exhaust manifolds on the sides of the engine^[1]. They are "pressure impulse" type, where each cylinder's exhaust is directly connected to the turbine to maximize performance.^[35] Wastegates are vacuum-actuated.^[36][g] Maximum boost is 1.4 bars (20 psi) gauge pressure.^[2]

The engine uses port and direct injection,^[1][h] with fuel pressure at 200 bars (2,900 psi).^[2][38]

The primary high temperature cooling circuit cools the engine, oil, and turbocharger via a mechanically driven water pump.^[40] The water flows through the engine laterally, from the outside in, to cool all cylinders evenly. Two air-to-liquid charge air coolers, one for each cylinder bank, dissipate the heat of compression via a secondary low temperature cooling circuit with an electric water pump.^[2][41]

The variable speed oil pump generates pressures of either 1.5 or 4.1 bar (22 or 59 psi)^[2] depending on engine speed, load, and temperature.^[42] Pumping a lower pressure reduces fuel consumption. It is driven by a chain, in a 1:1 ratio, via a sprocket on the crankshaft. A plate heat exchanger for cooling the oil is located in the inside the V between the cylinder banks.^[43]

For the GTA and GTAm models the engine was upgraded with reinforced connecting rods, additional piston oil jets, improved oil cooler, and higher boost to make 397 kW (540 PS; 533 hp).^[44]

The engine is used in the following models:

• Alfa Romeo Giulia Quadrifoglio
• Alfa Romeo Stelvio Quadrifoglio
• Alfa Romeo Giulia GTA and GTAm
• Alfa Romeo Giulia SWB Zagato
• Alfa Romeo 33 Stradale

The engine sends power through the ZF 8HP 75 automatic transmission. In Europe Alfa Romeo also offered the ZF S6-53 manual transmission until 2018.^[45]

The Maserati 3.0-litre V6 Nettuno engine, introduced in the Maserati MC20, shares many characteristics with the Alfa Romeo 690T and the Ferrari F154 engines.^[46][47]

The Alfa Romeo 33 Stradale features a larger 3.0-litre version of the engine, an evolution of the Nettuno,^[48] producing 456 kW (620 PS).^[49]

• Alfa Romeo Giulia Technical Training Quadrifoglio Mechanical Systems (PDF). FCA. Archived from the original (PDF) on 2023-01-29.
• Giulia 2018 Quadrifoglio Owner's Manual (PDF). FCA US LLC. Archived from the original (PDF) on 2023-01-17.