Alpine Presents Alpenglow HY6 with The Brands First 6 Cylinder Hydrogen Engine

Revealed in 2022 as a concept car designed as a blueprint for the brand's future direction in design and sustainable innovation, Alpenglow already showcased the high-performance potential of the hydrogen combustion engine, a realistic solution for offering sports models with high carbon reduction targets. In this way, Alpine is ready for possible changes in future regulations. It is also a symbolic application of the name Alpenglow, which takes on its whole meaning: an optical phenomenon that lets a glowing light shine on the mountains before sunrise, in other words, an evocation of the dawn of a new world.

Following on from the first prototype powered by a 340 bhp, turbocharged 2.0-litre 4-cylinder engine, this is the Alpenglow Hy6 equipped with an all-new engine that offers more than double the power. It is a ground-breaking 3.5-litre V6, developed entirely by Alpine for optimum hydrogen combustion. It produces 544 kW (740 bhp), or more than 150 kW/l (210 bhp/l), giving Alpenglow first-rate performance, ideally in line with the spectacular design of this rolling laboratory, which is evolving with the arrival of this new motorisation.

Exterior design

Since its first version appeared two years ago, the Alpine Alpenglow concept car has evolved through close collaboration between designers and engineers to combine aerodynamic efficiency with enhanced design. This Alpenglow Hy6 version, which features the new V6 engine, has various modifications and technical enhancements. At the same time, the styling of the concept's Specular Blue all-carbon bodywork has a more extreme edge.

The arrival of this engine is the real heart of this rolling laboratory. It has, therefore, been installed in a case that leaves it visible. It is protected by glass tinted with a touch of blue, while the engine bay has been carefully designed down to the smallest detail. The iconic shape of the rear window, reminiscent of the A110, incorporates two transparent NACA air intakes that feed two ducts leading to the gearbox oil cooler, contributing to the impression of lightness. The plenum (air intake manifold) stamped with a Hy6 logo recalls the treatment of the cylinder head covers on old racing cars. New air intakes have been incorporated to ensure the cooling of this larger engine, with a series of 3 louvres (x3) to ensure ventilation and contribute to the safety of the hydrogen engine's environment.

Creating lightness is always a challenge for the design team, and this is reflected visually in removing the bridge that used to link the rear wings, leaving them floating here and giving a clear view of the engine. This work has also resulted in lighter parts, thanks in particular to the use of carbon. The new Hy6 engine, which is twice as powerful as the Alpenglow Hy4 engine, is more performant and requires enhanced aerodynamic support. The response can be seen most clearly in the rear wing, which is still made of a transparent material for improved visual lightness but with a more aggressive, raised, racing-style appearance, incorporating new side blades and solidly supported by specific aluminium struts. As a result, the spoiler is more prominent, visible from the front of the prototype, while the shark-fin is larger and more prominent, bearing the Alpine logo, the chemical formula for hydrogen and a line of shading from magenta to blue, symbolising its virtuous combustion. The Inconel exhaust system integrated into the rear lights gives off water vapour when the car runs, giving the transparent spoiler a beautiful frosted effect.

Lastly, the wheels retain their structure and gradient, evoking speed even when stationary, in perfect harmony with the bespoke Michelin tyres, whose graphics match the wheels' design.

Interior design

The kinematics of the elytra-shaped door opening are designed to provide as much space as possible, making it easier to get on board. The driver and passenger can slide over the sidepods, angled towards the cockpit, and easily reach the perfectly adjusted bucket seats, upholstered in a new fabric that reacts to light in metallic and blue colours.

The triangle at the front of the cockpit is still present and is also one of Alpine's typical distinctive features, evoking the mountains. It provides several visual functions for the driver: it gives a signal and a direction, and it can change colour, like in a video game, to indicate for example the level of the lateral Gs in real time, engine speed, or information about passing speeds.

The dashboard features a magenta tubular crossbar partly hidden by a section in the shape of an aircraft wing. The materials used are reminiscent of the world of sports cars, with carbon fibre, aluminium and Alcantara upholstery embellished with 3D-printed motifs. There's also a magenta-coloured starter button and a racing steering wheel inspired by Alpine's racing cars. On the sides, the carbon skin covering the side fuel tanks suggests their shape. Lastly, dedicated slots have been integrated for mounting mini-action cameras to capture the sound and image of Alpine Alpenglow Hy6's laps around the track.

The new Alpine Hy6 V6: a unique engine entirely powered by hydrogen

The Alpine Alpenglow Hy6 hydrogen-powered rolling prototype is designed as a genuine race car based on an LMP3 carbon chassis. From the outset, the chassis has been designed to match the performance offered by the all-new Hy6 V6 engine, which more than doubles the power output compared with the 4-cylinder engine used in the first demo lab. Conceived from a blank sheet of paper, the Hy6 V6 is an unprecedented engine purposely developed by the Alpine teams at Viry-Châtillon for use with hydrogen. Two years of work went into its development. It was a considerable engineering challenge regarding the specific features of hydrogen combustion, which gave rise to an exceptional increase in expertise. Oreca is the technical partner that has made it possible to implement this savoir-faire in the engine's design.

The engine is a 3.5-litre V6 open at 100°, supercharged by two turbochargers. It consists of a solid aluminium engine block with a dry sump. A crankshaft with crankpins offset by 20° ensures smooth ignition. The cylinder heads are made from cast aluminium with an optimised cooling circuit. At the same time, valve timing is ensured by 4 chain-driven overhead camshafts and 4 valves per cylinder controlled by finger cogs. It is a 'super-square' engine with a 95 mm bore and 82.3 mm stroke, a highly advantageous format at high revs. The sound emanating from the Inconel exhausts system has been specially tuned to sing all the way up to maximum revs of 9,000 rpm. The engine's maximum power output is 740 bhp at 7,600 rpm, corresponding to an impressive specific power of 211 bhp/l for a top speed of over 330 km/h. A centrifugal clutch and an Xtrac sequential gearbox assist this Hy6 engine. Its development philosophy initially favours a version designed for racing but could be transposed to series production.

Formula 1 engine development methodologies have been used to define and fine-tune the elements at the heart of this engine's performance. The combustion chamber is designed to use hydrogen (more precisely, dihydrogen H₂), favouring turbulent movements to ensure that the mixture is homogeneous before the spark. It is a crucial point as hydrogen ignites over a wide range of richness, which makes it prone to generating abnormal combustions: pre-ignition (spontaneous auto-ignition before the spark plug sparks, producing extreme pressure levels), or knocking, which generates auto-ignition and shock waves. Particular care must be taken in preparing and injecting the mixture, supplemented by indirect water injection, which reduces Nox emissions while preventing these phenomena.

The three Alpenglow Hy6 tanks store hydrogen in gaseous form (2.1 kg each) under high pressure: 700 bars. They are located in the sidepods and aft of the cockpit, in ventilated compartments and sealed off from the passenger compartment. A pressure regulator reduces the pressure from 700 to 200 bars before dropping to the pressure required for direct injection into the combustion chamber.

Numerous measures have been taken to ensure absolute safety. The 700-bar composite cylinders are Regulation 134 certified*, valves have been incorporated for rapid fuel evacuation in the event of fire, hydrogen presence sensors are constantly on the lookout, a rigorous start-up procedure has been adopted with numerous checks, and, finally, a colour-coded system alerts the driver and emergency services according to the degree of severity of each type of incident.

*Regulation 134: European standard for hydrogen vehicle safety.

Hydrogen in competition, a technology of the future with great potential

The two leading solutions for hydrogen-powered propulsion are the fuel cell (which produces electricity to power an electric motor) and the internal combustion engine powered directly by hydrogen. Alpine has opted for the latter, as it combines several advantages of a race car, not least the very similar feel of the engine for the driver and a sound that is entirely in keeping with Alpine's racing philosophy. These advantages include an elevated power output, excellent efficiency under heavy loads, and reduced cooling requirements, as a large proportion of the heat dissipates through the exhaust system.

These arguments favour continuing along this path, which is the subject of Alpine's research and development to optimise this promising type of powertrain further. Regarding hydrogen storage solutions, Alpine is one of the leading manufacturers with a view to switching to liquid hydrogen, a paradigm-changing state of the art that can be better integrated into the car and refuelled quickly.

Alpine Racing is paying close attention to changes in competition regulations and notes the plan for the ACO and the FIA to authorise the participation of hydrogen-powered cars from the 2028 24 Hours of Le Mans onwards.