There were two factors at play here: the first that its powertrain setup, and in particular its turbo size, was not ideal for high-altitude racing in Mexico and Brazil.
But beyond that, Ferrari team principal Mattia Binotto confirmed after the last race that the Maranello team had to cut engine performance in the later stages of the year due to reliability issues. .
A few dramatic and costly engine failures earlier in the campaign – including Charles Leclerc’s outbursts in Spain and Baku, as well as Carlos Sainz’s fiery outing in Austria – had prompted things to be scaled back a bit while a solution was found. be put in place.
In a short reference, Binotto said: “We had to lower the power slightly. Yes, we had to.
But it has since emerged that Ferrari was able to get aggressive again in Abu Dhabi with its 066/7 engine, with the team believing they have found the solution to those earlier reliability issues.
According to sources, the weak element of the power unit had been identified as the spark plug in the pre-chamber.
It was the latest evolution of the TJI (Turbulent Jet Ignition) combustion system that Mahle made available to Ferrari in 2016, and which helped the team close the power gap with Mercedes.
In the six years since, huge progress has been made in developing an optimized system for the latest generation of power units homologated to be frozen until the end of the 2025 season.
The TJI system includes the spark plug and the fuel injector. Both are housed in a well in the cylinder head, and the two elements work together to help maximize power.
Only 2-3% of the fuel is injected into the pre-chamber, the rest is distributed over the surface of the piston. The mixture inside the “plug” is particularly rich, while the combustion agent in the chamber is leaner, with more air than fuel.
Enrico Gualtieri, Power Unit Area Manager, Ferrari, Carlos Sainz, Ferrari F1-75
Photo by: Ferrari
Ignition of the candle reacts with the very rich mixture in the pre-chamber, and causes the creation of plasma jets through open holes in the cap. Thanks to a very high pressure, the lean mixture self-ignites at several points in the chamber with a flame propagation that extends to the entire volume of the cylinder.
The system makes it possible to shorten the combustion times, which offers two advantages.
First of all, the very lean mixture in the chamber makes it possible to reduce the harmful effects of detonations, which makes it possible to increase the compression ratio for more performance.
Additionally, with teams still limited in how much fuel can be used in a race (currently 110kg), for the same amount of fuel injected, greater thermal efficiency is achieved – which also equates to more power. .
Ferrari pushed the development to exploit the maximum pressure of the injection system, which reaches 500 bar as permitted by regulations, and aimed for five discharges for each engine cycle.
But the extreme concept caused the internal temperature to rise, causing the spark plug to suffer and eventually break.
Engineers therefore had to tweak their mapping so as not to push the spark plug over the limit, while an external supplier worked on delivering new materials to ensure the component could cope with the needs of the motor in maximum power mode.
Ferrari’s performance in Abu Dhabi suggests the spark plug problem appears to have been resolved, which will be a big boost for Ferrari’s hopes for 2023 where it knows it cannot afford a repeat. of its reliability issues.