Engine Weight Reduction Technologies - Honda Insight Owner's Manual

E W R
NGINE EIGHT
All engine parts have been made as light as possible. Major weight-reducing features are:
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Sleeveless cylinders with minimal dimension between bores
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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 of plastic.
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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.
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Single rocker arm shaft shared by intake and exhaust valves
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Rocker arms made of aluminum
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Optimally light pistons.
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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.
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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.
T
EDUCTION ECHNOLOGIES
Magnesium-alloy oil pan
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