All engine parts have been made
as light as possible. Major weight-reducing features are:
- Sleeveless cylinders with minimal
dimension between bores
- The intake manifold used on
the Insight's 1.0-liter engine is made out of plastic resin instead
of aluminum alloy. The entire manifold weighs only 2.2 pounds, roughly
half the weight of a comparable aluminum manifold. The individual
pieces that make up the manifold, such as the intake runners, plenum
chamber and throttle-body mounting, are permanently connected with
a vibration-welding technique. The cylinder head cover is also made
- Additional weight-saving engine
components made with plastic resin include a 0.39-pound water-pump
pulley, a 0.2-pound air-intake tube and a 0.88-pound valve cover.
rocker arm shaft shared by intake and exhaust valves
- Rocker arms made of aluminum
- Optimally light pistons.
- Borrowing the technology from
Honda's high-performance S2000 sports car, the IMA engine uses special
compact, high-strength, forged-steel, carburized connecting rods.
Carburization toughens the rod's surface so that it resists crack
formation. Carburizing allowed Honda engineers to reduce the cross
section of the connecting rods, thereby reducing their weight (always
a penalty in a reciprocating engine) by 25 percent, while increasing
their strength by more than 50 percent.
- The Insight IMA engine features
a magnesium-alloy oil pan. Like a cast-aluminum pan, the Insight's
magnesium pan adds stiffness to the engine block, helps muffle engine
noise and also helps to cool engine oil, but it is 35 percent lighter
than aluminum. The magnesium alloy specified for the Insight engine's
oil pan is a new type that exhibits less thermal-induced expansion
and contraction (creep) at high temperatures, so the oil pan remains
oil tight. Honda engineers designed additional weight-saving measures
into the Insight's magnesium oil pan by incorporating the engine
oil-filter bracket, AC-compressor bracket and an engine-block stiffener
into the casting.
Magnesium-alloy oil pan