Ferrari was so proud of its five-valve cylinder heads, it changed a naming convention that ran back over 25 years. For its previous mid-engine two-seaters, the three-digit name was derived from ...

Thunder Power's 4-valve cylinder head conversion for big-block Chevys bolts right onto production iron or aftermarket aluminum cylinder blocks. The heads even have the necessary bosses to add an extra ...

"After many years of involvement with the early automobile manufacturers, Harry Weslake founded Weslake and Company in 1934 to act as consultants to the makers of internal combustion engines. Over the ...

Porsche never made a four-valve head for an air-cooled 911. The 959 had 24 valves, but its heads were water-cooled. It wasn't until the first water-cooled 911, the 996, arrived in 1998 that the iconic ...