FIA Seeks Black-and-White Hot-Engine Test for Ratio Rule

Engine manufacturers and the FIA scheduled two meetings for next week — a Monday technical workshop followed by Thursday’s Power Unit Advisory Committee (PUAC) — to try to resolve a dispute over an alleged compression-ratio loophole in the 2026 Technical Regulations. The issue centers on Article C.5.4.3, which caps geometric compression ratio at 16.0 and requires measurement at ambient temperature; checks to date have been performed under ambient conditions, while the FIA is exploring methods to measure compression ratios with engines hot after an earlier expert gathering produced only partial agreement and requested additional test data. Ferrari power unit technical director Enrico Gualtieri described talks as positive but said more work and data were needed, and FIA single-seater technical director Nikolas Tombazis said officials wanted the matter “put to bed in a totally absolute black and white way” before the Australian Grand Prix at Albert Park.

Reports have identified Mercedes as the team most likely to have exploited the regulatory ambiguity, with Red Bull implicated to a lesser extent; the interpretation is said to allow higher on-track compression and a potential performance gain of up to about 15 bhp, roughly 0.4 seconds per lap. Several manufacturers, including Ferrari, Honda and Audi, sent a joint letter to the FIA before Christmas raising concerns, and Red Bull’s similar interpretation helped align other firms politically in calls for guarantees about engine legality. Former driver Ralf Schumacher publicly urged Ferrari to “keep their mouths shut,” invoking the team’s 2019 fuel-flow controversy and a subsequent confidential agreement with the FIA, while also praising the engineers who flagged the loophole.

The FIA has outlined three possible remedies to address the situation: permit additional spending to redesign engines (considered unlikely), impose limits on the performance extractable from Mercedes’ Petronas fuel, or require a legal declaration from Mercedes affirming compliance — with Motorsport Italia noting that a false declaration could carry severe consequences, including potential disqualification. No immediate rule change or sanction has been announced; officials emphasize that next week’s meetings are intended to build consensus on a technical testing method and any formal testing procedure or rule amendment would be handled at PUAC level. It remains unclear whether teams unhappy with the pace or outcome of the process will lodge formal protests at the start of the 2026 season if a clear resolution is not reached in time.