Could hydrogen come to the rescue of the IC engine in motorsport? On the face of it, the most likely saviour is a sustainable gasoline-type fuel, as investigated elsewhere in this issue. Nevertheless, there is growing interest in hydrogen, particularly since the supply and onboard storage of it are challenges shared with fuel cell electric powertrains.
Motor manufacturers might these days be battery electricfocused, but a good number are also looking at possibilities for hydrogen fuel cells. In our world, Le Mans is busy preparing the ground for them rather than battery powered electric-engined Prototypes in 2024 or ’25. Consequently the ACO is readying the necessary hydrogen infrastructure, which will be equally applicable to hydrogen-fuelled IC engines (H2ICEs).
The Alpine Alpenglow concept car is hydrogen-fuelled
Toyota is currently the only manufacturer exploring H2ICE potential on track. As we saw in RET 142 (October 2022) it has been racing an H2ICE GR Corolla in the 2022 Super Taikyu series in Japan, as well as June’s Fuji 24-hour race. A sister H2ICE rally Yaris using essentially the same I3 turbo has subsequently been demonstrated at this year’s World Rally Championship Ypres rally in Belgium.
The GR Yaris H2 rally car and the GR Corolla H2 racecar share the G16E-GTS engine from the Yaris production car. This 1.6 litre I3 turbo has been converted to run on hydrogen via a special Denso injection system. It might be recalled that GR Powertrain Development Division general manager Masakiyo Kojima told RET, “This project is at a very early stage of development, so we have made only small modifications to the production engine.
“The standard injectors are built for a liquid, but we are using hydrogen gas, so new injectors had to be fitted. We have also removed the fuel pump. The pressurised hydrogen tank and a regulator are directly connected to the hydrogen injectors.”
In Belgium, Toyota Gazoo Racing ran the GR Yaris H2 on two stages ahead of the regular WRC competitors. Four-time World Rally Champion Juha Kankkunen drove the car on SS3. Team founder Akio Toyoda got behind the wheel the following day, over SS11.
He remarked of his Ypres adventure, “I want to keep the engine’s vibration and exhaust sound in motorsport. While we are trying to achieve carbon neutrality, we still want to keep the excitement. It was great that we were able to share that feeling in Europe.”
In the WEC, Toyota’s primary rival since the advent of Hypercar has been the grandfathered Rebellion-Gibson V8 LM P1 campaigned by Alpine, which won two of this year’s six races. Next year the door has been closed to grandfathered LM P1s, so Alpine will step down to LM P2 while awaiting the arrival of its LMDh car for the 2024 season. LMDh will of course be performance-balanced with Hypercar to provide equal opportunity for overall victory at Le Mans.
Toyota introduced the WRC to H2ICE in Belgium
We don’t yet know anything about the Alpine LMDh powertrain other than by regulation it will have to incorporate the class’ spec hybrid system, while there have been hints of a V6 turbo. The engine is being developed in-house, probably in conjunction with Mecachrome, which builds the brand’s Formula One power units.
We do know that Alpine’s Formula One V6 turbo has been discounted as too complex and too expensive to use as a base for LMDh. Recall therefore that Mecachrome produced an LM P1 version of its current Formula Two 3.4 litre V6 turbo (RET 113 September/October 2018), a unit that would lend itself ideally and cost-effectively to development for LMDh.
Meanwhile, at the recent Paris Motor Show, Alpine presented its Alpenglow concept car, which hinted at the striking look its LMDh might adopt. Alpine team manager Philippe Sinault has remarked, “The virtue of the Alpenglow is to foreshadow certain features of our LMDh in 2024. Alpine’s design team came to our workshops recently to present their results, and it was an important moment of collaboration. We are in full swing.”
Technical details of the Alpenglow were closely guarded – not even the engine configuration was revealed. But interestingly it was said to have an H2ICE fed by twin 700 bar tanks mounted either side of the vehicle. By regulation, the 2024 Alpine LMDh will use the spec Hypercar/LMDh fuel supply (IMSA or ACO according to the race event) but the marque is clearly interested in H2ICE.
Indeed, Alpine owner Renault remarked, “With its hydrogenpowered IC motor, the Alpenglow procures the same driving pleasure to be expected of an Alpine car on both closed circuits and the open road… it gives us a glimpse of a future… where the excitement of driving is enhanced through innovative technology based on a hydrogen-powered IC engine that is still as musical to the ears of car enthusiasts.”
Earlier, Alpine CEO Laurent Rossi told UK magazine Autocar, “We know that Le Mans is promoting hydrogen fuel cells, which is one step forward, but we want to go another step forward and use hydrogen as a fuel, so we could use a V6 – a hybridised V6 – powered by hydrogen.” One imagines Toyota would also be keen to exploit the forthcoming Le Mans hydrogen infrastructure in that manner. Thus it isn’t inconceivable that in the not too distant future, Le Mans will pit Hypercar and LMDh cars using sustainable fuel against new-generation Prototypes using fuel cells plus others that use an H2ICE powertrain.
H2ICE challenges
Wayne Ward noted in RET 129 (February 2021) that although hydrogen has a much higher heating value than gasoline – 120 MJ/kg compared with 43.4 MJ/kg – its low density means its energy per litre is low. In view of that, these days it is typically stored on board at a pressure of 700 bar. Ward noted that to store 2300 MJ of energy on board – roughly the amount stored in a full LM P1 fuel tank – requires 19.17 kg of hydrogen or 54 kg of gasoline. However, even at 700 bar the hydrogen takes up a volume of 456 litres, while the gasoline has a volume of only 67 litres.
The Toyota GR Corolla H2 carries 7 kg of hydrogen at 700 bar in a 180 litre tank. At Fuji, although it had competitive pace, its more frequent and longer refuelling stops meant that while it finished the 24 hours healthily, it lagged well behind its conventionally fuelled rivals. A greater mass of hydrogen can be stored in a given capacity in liquid form, which means it has been reduced to a temperature of at least -253 ºC. Another approach is to create a hydrogen paste. We can expect though that such promising but challenging methods will be long- rather than short-term solutions.
Nevertheless, it will be fascinating to see how the ACO’s commitment spurs development of hydrogen storage for racecars. Before Toyota’s GR Corolla H2, the last time we saw an H2ICE in competition was when Aston Martin raced a V12 Rapide S in the 2013 Nurburgring 24-hour race (RET 70, May 2013). That car carried 3.2 kg of hydrogen at only 350 bar in a 200 litre pressure tank, which was sufficient for one 25 km lap of the Nurburgring.
The Rapide S was dual fuel, using either port injected gasoline or (further upstream) port injected hydrogen or even a combination of the two fuels. The Rapide S had its hydrogen supply feed the dedicated solenoid-type injectors via a pressure regulator. The key was in the control of those injectors, which had been designed specifically to dispense hydrogen.
A challenge highlighted by the Aston Martin project is the inherently lower energy output of hydrogen combustion given conventional IC engine technology. The Rapide S lost 17% of its power when switched from the fuel it had been optimised for to the alternative. The regulations capped power at 560 PS, and the loss running hydrogen was overcome by supercharging. No boost was required when running on gasoline; over 1.0 bar (gauge pressure) when switched to hydrogen-only operation.
AVL’s new H2ICE race engine
Hydrogen burns six times faster than gasoline, and needs a relatively small amount of ignition energy. Its relatively fast and low-temperature combustion mean that the flame travels faster and further, which can create additional thermal and mechanical stress. At the same time, hydrogen lacks lubricity. However, those issues are straightforward to address through normal engine development.
On the other side of the coin, an H2ICE can be controlled via the amount of hydrogen injected, rather than throttled, to the benefit of engine efficiency. But at the same time, hydrogen’s fastburning nature and the low ignition energy requirement mean there is far greater danger of pre-ignition compared with using gasoline.
Partly for this reason, hydrogen tends to be run with an excess of air. The stoichiometric ratio of hydrogen is 34:1, and an H2ICE is typically run at lambda 2.0-3.0. The empirical evidence is that it is then an extremely challenging control issue to keep combustion stable over the entire operating range.
AVL RACETECH H2ICE
AVL RACETECH recently unveiled its own H2ICE, a direct injection 2.0 litre I4 turbo on the face of it typical of such configuration race engines. However, it exploits new technology that avoids the usual drawback of having to operate with a pronounced lean-burn approach at the cost of performance relative to a gasoline fuelled-equivalent.
Paul Kapus, responsible for spark ignited engines and concept vehicles at AVL, explains that the key to this is the integration of what is termed “intelligent” water injection. He reports: “there is an injector for each cylinder in the intake port that injects water at a pressure of around 10 bar. When this water evaporates it cools the charge (similar to having an additional charge air cooler). This helps to avoid knocking and preignition. Preignition is one of the big issues with hydrogen as hydrogen only needs a very low ignition energy.
“The evaporating liquid has a strong cooling effect in the combustion chamber. This and a ‘moderation effect’ on combustion are the two main advantages. Moderation means that water injection can shape the rate of heat release and by that we can mitigate knocking. Water injection enables stoichiometric or near stoichiometric operation of a hydrogen engine.
“A hydrogen engine can easily run Lambda = 3 but that would mean very high boost pressure at full load for our target output. We will run that lean at part load only; at full load we can run in the
range of Lambda = 1 to roughly = 1.5, so only slightly lean. The less lean we have to run the engine the less boost pressure is needed for a given performance level.”
Kapus points out that designing the necessary injectors and valves required precise knowledge of the overall system behaviour in respect of all air, fuel, and exhaust gas flows. For this AVL used its tried and tested simulation models and 3D flow calculations. “In order to get a good result we needed to simulate,” Kapus emphasises.
This work ensured that the mechanical limits of the engine were not exceeded and the upshot was an H2ICE that has the potential to generate a performance level of as much as 150 kW / 200 bhp per litre. Kapus tells us that the engine is targeted at production engine based, customer focused racing classes. He says, “the typical customer racing class engine is in the range of 350 bhp. We want to achieve at least this level of performance.”
Kapus confirms that this H2ICE is using a comparable level of engine speed – around 6500 rpm – and compressor output to that of the reference engines. While he doesn’t yet wish to specify compression ratio or boost pressure or hydrogen injection pressure he can tell us that “in order to get best utilisation of the pressurised hydrogen tank a low injection pressure is the target.”
Interestingly on the road car side AVL has attained a thermal efficiency of 42 – 43% for hybrid engines running on hydrogen. Kapus points out, “the main target for this racing engine is power, not efficiency. Nevertheless, we will achieve efficiency levels similar or better than those from a comparable gasoline racing engine.”
Kapus adds: “Realising performance values at motorsport level with a hydrogen internal combustion engine is an incredibly complex technical challenge. But our prototype will prove it can be done. The basic technology of a gasoline engine and a hydrogen combustion engine is very similar – in contrast with fuel cell technology. Which is why our concept is a very good fit for the economical approach of customer racing, since the adaptations required are very straightforward. The main aspect to be further developed is the injector for hydrogen – especially for direct injection.”
This is the first race engine AVL has developed under its own brand, AVL RACETECH (formerly AVL Racing). We look forward to providing an in depth report on this intriguing project in a future issue of RET.