In the last round of the 2022 Formula One season, the Abu Dhabi Grand Prix, Scuderia Ferrari was able to use the full power of the 066/7 engine with more extreme mappings than usual for a very simple reason: it seems that the Maranello engineers led by Enrico Gualtieri have found the solution to the reliability problems that compromised the 2022 F1 world championship as the Italian side was not able to capitalize on the full potential of the Superfast power unit designed by engineer Wolf Zimmermann.
The weak element was the spark plug with the pre-chamber combustion: this was in fact the latest evolution of the TJI combustion system that Mahle had made available to Ferrari in 2016 and which allowed the Maranello team to recover the power gap to the Honda and Mercedes engines. TJI is the acronym for Turbulent Jet Ignition.
In the last six years huge progress has been made in the development of a system that has been revised and corrected to meet the needs of the latest generation of power units, which were homologated at the beginning of the year and that will be frozen until at the end of the 2025 Formula 1 season.
The Turbulent Jet Ignition system includes the spark plug and the fuel injector: both are located in the cylinder head. The two elements come together in a duct that Motorsport Italy calls the “hood”, which leads to the pre-chamber.
Only 2-3% of the fuel is injected into the pre-combustion chamber, the rest spreads over the piston surface. The mixture inside the “hood” is particularly rich, while the combustion agent in the chamber is clearly leaner with more air than fuel.
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The ignition of the spark plug triggers the explosion of the very rich mixture in the pre-chamber and causes the propagation of plasma jets through the small holes opened on the “cap” and, thanks to a very high pressure, the mixture self-ignites in several points of the chamber with a flame propagation that extends to the entire volume of the cylinder.
In this way it is possible to shorten the combustion times, gaining two advantages: thanks to the very lean mixture in the chamber, the harmful effects of detonations are reduced, being able to increase the compression ratio and therefore performance. Not only that, but it is clear that with a quantity of fuel limited by regulation (110 kg for a Grand Prix), for the same injected fuel, a greater thermal efficiency is obtained which is worth more power.
Ferrari pushed the development of the Superfast engine to exploit the maximum pressure of the injection system that by regulation reaches 500 bar, aiming for five discharges for each engine cycle. Taking this concept to extremes has led to temperature increases which have affected the spark plug, leading to technical failures.
Scuderia Ferrari therefore had to use less aggressive mappings that would not send affect the spark plug, while the external supplier tried to work on the materials to ensure an element capable of responding to the needs of the 066/7 in maximum power mode. The Abu Dhabi Grand Prix suggests that the spark plug problem seems to have been solved and for 2023 the prospects for the reliability of the internal combustion engine should be a lot better.