70AARCUDA
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The 1.8L (LUW) engine uses a 2-stage intake "resonator" manifold.
From the GM literature:
"The Ecotec 1.8L’s two-stage variable intake manifold optimizes fuel economy and performance. At engine speeds below 4,000 rpm, inlet air passes through 35.8-inch-long (910 mm) intake tracts that help increase torque. At speeds greater than 4,000 rpm, a rotary sleeve within the lightweight composite intake manifold closes off the full length of the intake tracts, forcing air through a shorter, 10.2-inch (260 mm) path that helps build horsepower."
Summary:
• below 4,000 rpm = 35.8" (910mm) intake tract...for torque.
• above 4,000 rpm = 10.2" (260mm) intake tract...for horsepower.
From the GM literature:
"The Ecotec 1.8L’s two-stage variable intake manifold optimizes fuel economy and performance. At engine speeds below 4,000 rpm, inlet air passes through 35.8-inch-long (910 mm) intake tracts that help increase torque. At speeds greater than 4,000 rpm, a rotary sleeve within the lightweight composite intake manifold closes off the full length of the intake tracts, forcing air through a shorter, 10.2-inch (260 mm) path that helps build horsepower."
Summary:
• below 4,000 rpm = 35.8" (910mm) intake tract...for torque.
• above 4,000 rpm = 10.2" (260mm) intake tract...for horsepower.
