The 90-degree small-block design, which dates back to 1955 in the 195-hp Corvette, continues to use two valves per cylinder and an overhead-valve architecture requiring one pushrod per valve. “The 2-valve technology is not a disadvantage in terms of performance,” Damico says. “We can make the engine lighter and the packaging better.”
While most other auto makers have moved on to more sophisticated overhead-cam architectures, with the exception of Chrysler’s Hemi V-8, Damico says the OHV design offers some key advantages, such as the ability to integrate fuel-saving cylinder deactivation with little extra cost.
Plus, OHV powerplants tend to be much easier to package because the cylinder heads on OHC engines – especially those with two camshafts per cylinder bank – take up a lot of room under the hood, Damico says.
“You can’t put a DOHC engine in a Corvette,” he says. Jamie Meyer, product integration manager-GM Performance Parts, estimates one-third of the approximately 40,000 classic vehicles at the recent Detroit-area Dream Cruise event used GM small-block engines, many of them under the hoods of competitor nameplates.
http://wardsauto.com/ar/gm_makes_case_110831/