The 1991 Acura NSX features VVIS (Variable-Volume Intake System) which is a magnesium plenum below the intake chamber which opens 6 butterfly valves above 4800 rpm. This allows for a larger air passage to the engine at higher rpm"s. The "91 NSX also features VTEC (Variable Valve Timing and Lift Electronic Control). A normal cam lobe is accompanied by a second and more aggressive cam lobe that turns on at around 5800 rpm that keeps the valves open wider and longer. The automatic version of the "91 NSX only had 252 bhp.

acura-nsx-1991-1