Gordini had some decidedly odd ideas.
High compression, hemispherical heads lead to long thin combustion chambers. This gives a slow burn (lots of ignition advance needed) so more heat is lost into the piston and head (overheating, pinking, holed pistons). One way to counter this is to twin plug the engine. This greatly shortens the burn time and you can reduce the ignition advance quite a bit (5° to 10°) which also reduces all the bad things above. Finding the space for two plugs can be difficult and Gordini used true hemi chambers. So he made a a small chamber for the spark plug above the combustion chamber. Two small passages led to the combustion chamber. The idea was this would function like a twin plug head. Well, it didn't. Gordini retired/left and Renault took over. They resigned the chamber so it had an aggressive squish area on one side. This created a lot of turbulence which greatly speeds up the burn time. The engine now produced more power and less heat. Win, win and no magic required.
