My car is Chrysler 300C V6 2013 with SOHC So it write 24 valve as you explain have to 12 valves Because you say each Cylender on top only 2 valves it means my car have to 12 valves but actualy 24 valves please more explain to me Many thanks
Each cylinder needs at least 2 valves: one intake valve to draw in the air and fuel mix, and one exhaust valve to release the exhaust gases after combustion.
To make the engine more efficient, sometimes more than 2 valves are used. These days, it's common to have 4 valves per cylinder: 2 intake valves and 2 exhaust valves.
This helps because 2 valves allow more air to be drawn into the cylinder than one, in other words it reduces the air resistance in the intake.
with a SOHC the single cam per cylinder bank operates both the Intake and Exhaust valves. A DOHC has a cam for Intake valves and another cam for operation of Exhaust valves. Both SOHC and DOHC can have any number of exhaust and intake valves per cylinder - in practice we see 1,2 or 3 intake or exhaust valves per cylinder regardless of the number of cams.
A SOHC engine can still have 4 valves per cylinder as explained above but the phasing between the intake and exhaust timing cannot vary like it can in a VVT DOHC engine.