Breathing: Ability of an engine to take in air-fuel mixture and to discharge exhaust gases efficiency. Many of the modern car engines are provided with 4 valves per cylinder for better breathing. Related posts: Personnel Management Operative Functions Administrative Role of PM Competency HR Management Role Change Personnel Policies Personnel Procedures Appealed Policies Implied Policies Specific Policies Personnel records Research Pure research Personnel research Attitude or Opinion Survey Turnover Secondary research Applied research Personnel audit Read more articles Previous PostBreakerless ignition Next PostButterfly Valve