Imperial College London


Faculty of EngineeringDepartment of Mechanical Engineering

Chair in Thermofluids



+44 (0)20 7594 7032p.aleiferis




Ms Serena Dalrymple +44 (0)20 7594 7029




615City and Guilds BuildingSouth Kensington Campus






BibTex format

author = {Roberts, P and Kountouriotis, A and Okroj, P and Aleiferis, P and Cooper, B},
doi = {10.4271/2018-01-0892},
journal = {SAE Technical Paper Series},
title = {Effects of Valve Deactivation on Thermal Efficiency in a Direct-Injection Spark-Ignition Engine under Dilute Conditions},
url = {},
volume = {2018},
year = {2018}

RIS format (EndNote, RefMan)

AB - Reported in the current paper is a study into the cycle efficiency effects of utilising a complex valvetrain mechanism in order to generate variable in-cylinder charge motion and therefore alter the dilution tolerance of a Direct Injection Spark Ignition (DISI) engine.A Jaguar Land Rover Single Cylinder Research Engine (SCRE) was operated at a number of engine speeds and loads with the dilution fraction varied accordingly (excess air (lean), external Exhaust Gas Residuals (EGR) or some combination of both). For each engine speed, load and dilution fraction, the engine was operated with either both intake valves fully open - Dual Valve Actuation (DVA) - or one valve completely closed - Single Valve Actuation (SVA) mode.The engine was operated in DVA and SVA modes with EGR fractions up to 20% with the excess air dilution (Lambda) increased (to approximately 1.8) until combustion stability was duly compromised. At 1500 Revolutions Per Minute (RPM), 3.6 bar and 7.9 bar Gross Mean effective Pressure (GMEP), the dilution tolerance of the engine was significantly increased for a given combustion stability limit utilising SVA. This resulted in fuel consumption reductions of up to 3.8% and 3.1% respectively for these two engine speed and load conditions as a result of being able to operate the engine with more thermodynamically attractive mixtures when adopting SVA. At 2000RPM, 9.8 bar GMEP, the dilution tolerance was only marginally increased which resulted in a fuel consumption reduction of 1.3% when adopting SVA over DVA (for the same reasons outlined above).Increased dilution tolerance in all cases was achieved as a result of significant enhancement in charge motion when adopting SVA. By enhancing the in-cylinder charge motion (confirmed using Computational Fluid Dynamics (CFD)), ignition to 10% Mass Fraction Burned (MFB) and 10-90% MFB durations for equivalent levels of dilution were significantly shorter when adopting SVA. This therefore allowed greater dilution tolera
AU - Roberts,P
AU - Kountouriotis,A
AU - Okroj,P
AU - Aleiferis,P
AU - Cooper,B
DO - 10.4271/2018-01-0892
PY - 2018///
SN - 0148-7191
TI - Effects of Valve Deactivation on Thermal Efficiency in a Direct-Injection Spark-Ignition Engine under Dilute Conditions
T2 - SAE Technical Paper Series
UR -
UR -
VL - 2018
ER -