Noise Reduction

Honda is working to reduce noise during acceleration. The main source of acceleration noise is the engine, especially in the air intake and exhaust systems. The technologies presented here were implemented in the Crossroad, released in February 2007, to suppress intake and exhaust noise, reducing exterior noise to 73dB (A), lower than the 76dB (A) required by regulations.^*

*1.8-liter five-speed automatic transmission VTEC vehicle

Case Study

Engine Noise Reduction Technology •High-rigidity cylinder block •High-rigidity crankshaft •High-rigidity chain case •Engine chamber acoustic material Intake noise/radiation noise reduction technology •Large, high-rigidity air cleaner •Large, high-rigidity resonator chamber	Cylinder Block Exterior Curved surfaces and rib layout for high rigidity and radiation noise suppression	Chain Case Structure •Curved surfaces for high rigidity •Reduction of radiation noise	Intake System •High-volume resonator •chamber for noise reduction
Exhaust noise reductionbr •Large, noise-absorbing chamber •Large muffler	Crankshaft •Pin diameter/width, journal diameter/width optimized •Optimal balance weight for stable crank operation and reduced impact	All-aluminum lower block structure and stiffener-integrated aluminum oil pan •Improved crank support and power plant rigidity