A Comparative Study of Variable Camshaft Phasing and Port Throttling for Performance and Emissions

An experimental study has been performed to analyse and compare the effects on performance and emissions of two forms of Internal Exhaust Gas Recirculation (IEGR) systems. Variable valve event phasing, specifically increasing intake and exhaust event overlap, through control of the intake camshaft, has been used as an IEGR control mechanism and for increased full load performance. Port throttling in combination with long valve event overlap periods has been used to increase peak torque and power and when allied to a single upstream throttle, IEGR control has been demonstrated. Barrel throttles have been used for the port throttled variant and this type of port throttle is responsible for some of the benefits found.