The Acura NSX engine went through two major changes that can be classified as “different” engines. The original NSX engine was a 3.0-liter extruded aluminum VTEC (variable valve timing) V6 engine fitted with an electronic throttle. In 1997, the engine displacement was increased to 3.2-liters, and the inner cylinder walls were made from a thinner fiber-reinforced metal (FRM). This new engine, the C32B, was lighter and produced 20HP more than the original design. The second engine design change occurred in 2002, when the NSX engine started using a DOHC (double over-head cam) design. Honda never identified any other changes, if any, that were incorporated into the 3.2-liter V6 DOHC engine. However, over its life-cycle, the body and chassis of the vehicle went through considerably more changes.