Engine Block, Cylinder Heads, Crankshaft, Pistons (return)

To achieve both light weight and durability, the engine block is made of aluminum alloy. While cast iron cylinder liners are used on the 3.0-liter engine, the cylinders on the 3.2-liter V-6 are made using an advanced metallurgical technique called Fiber Reinforced Metal (FRM), in which an ultra lightweight alumina-carbon fiber is cast into the traditional aluminum alloy for enhanced rigidity. This process allows displacement to be increased without increasing bore centers while providing outstanding cooling characteristics.

The 3.2-liter engine has cylinder bore surfaces consisting of a 0.5 mm-thick layer with fibers of carbon and alumina (aluminum oxide, or Al2O3) in the aluminum alloy. In production, the cylinder block's aluminum alloy is poured around cylinder cores composed of these two fibers. The cores absorb the molten aluminum during the casting. After casting, the cylinders are bored to a slightly smaller diameter than the outside diameter of the cores, leaving a tough, wear-resistant, composite cylinder wall integral with the block but reinforced by the fibers. The process allows larger bores within the same external block dimensions and bore spacing, and makes open-deck block construction possible. This is appropriate for the 3.2-liter NSX engine's higher performance level. The elimination of iron cylinder liners allows a weight reduction of 5.3 lbs. for the larger displacement engine.

Because aluminum-on-aluminum is not an ideal combination for durability with a piston sliding in a cylinder, the 3.2-liter aluminum pistons are given an iron coating. The piston crown has been reshaped to improve heat resistance, and the pin diameter enlarged to cope with the higher power output. Conventional aluminum pistons are used in the 3.0-liter engine with iron liners.

The crankshaft on the NSX engine is a forged unit made of a special high-strength steel to cope with the high power output of both engines.

The low-pressure cast aluminum cylinder heads maximize flow into the combustion chambers in the 3.2-liter engine, where 36 mm intake valves are used. Even though the valve diameter is 1 mm larger than in the 3.0-liter engine, a unique cup shape is incorporated into the valve head to allow it to maintain the same weight. To further increase air flow, a special four-angle valve-seat machining process is used to create a gentle radius leading from the intake port into the combustion chamber - a process typically reserved for racing applications. The head gasket on the 3.2-liter V-6 is made of stainless steel to ensure a positive seal with the FRM cylinders. The combustion chamber for both engines is a pent-roof design with generous squish area to promote swirl and enhance combustion efficiency. The spark plug is centrally located for optimum flame propagation and features a platinum tip for improved durability and longer service life.