Although the 3.8-litre and 4.0-litre flat-six engines are naturally aspirated, high-rpm circuit driving generates substantial thermal loads across the cylinder heads and oil passages. Effective thermal management is vital to prevent the engine control unit from retarding timing or restricting power output. Optimising cooling efficiency on track-driven 991 GT3 models typically involves upgrading the frontal cooling capacity using enlarged centre radiators, fitting heavy-duty oil coolers to control lubricant breakdown, and utilising uprated water pumps to maintain steady coolant flow through the block during extended sessions.