page_title: Multi-valve
section_title: Alternative technologies
hierarchical_section_title: Multi-valve / Multi-valve rationale / Alternative technologies
caption_attribution_description: English: Cutaway model of i-AVLS (SUBARU EJ25 SOHC engine) by OTICS Corporation at Tokyo Motor Show 2007. 日本語: i-AVLS（スバルEJ25エンジンに搭載）のカットモデル。東京モーターショー2007のオティックスブースにて。
context_page_description: In automotive engineering a multi-valve or multivalve engine is one where each cylinder has more than two valves. A multi-valve engine has better breathing and may be able to operate at higher revolutions per minute than a two-valve engine, delivering more power.
context_section_description: Turbocharging and supercharging are technologies that also improve engine breathing, and can be used instead of, or in conjunction with, multi-valve engines. The same applies to variable valve timing and variable intake manifolds. Rotary valves also offer improved engine breathing and high rev performance but these were never very successful. Cylinder head porting, as part of engine tuning, is also used to improve engine performance.
caption: Cutaway model of Subaru's i-AVLS variable valve timing system on SOHC 4-valve-per-cylinder EJ25 boxer engine at Tokyo Motor Show 2007.
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