Do F1 race cars use a 4 valves per cylinder or 5 valves?

You mean vw and there funky 5v setups. More valves = more air The 5v means the can have more variations with the active cam timings. More duration and less lift. Means less chances of interference. The little 1. read more

Formula 1 engine manufacturers use a pneumatic system to close the valves to allow for very high RPM without valve float. The main benefit of the desmodromic system is the prevention of valve float and that there are no heavy power robbing springs used to close the valves, better protection for the engine if it is over revved, and better performance and/or overall efficiency. read more

A multi-valve engine design typically has three, four, or five valves per cylinder to achieve improved performance. Any four-stroke internal combustion engine needs at least two valves per cylinder: one for intake of air and fuel, and another for exhaust of combustion gases. read more