Comparison of Otto cycle and Atkinson cycle with optimized Intake cam profile of a turbocharged spark ignition engine

Mohammadi, A.; Mohsenirad, Mohsen; Ajami, Nima; Parivar, Amirhossein; Nejat, Mohammad

doi:10.22034/er.2026.2078266.1120

Comparison of Otto cycle and Atkinson cycle with optimized Intake cam profile of a turbocharged spark ignition engine

Articles in Press

Document Type : Original Article

Authors

A. Mohammadi ¹

mohsen mohsenirad ²

nima ajami ²

amirhossein parivar ²

mohammad nejat ²

¹ Lavizan, Shabanloo St, Departm

² ipco

10.22034/er.2026.2078266.1120

Abstract

This study investigates the performance of a spark-ignition engine with an increased effective compression ratio achieved through Atkinson-cycle operation via intake cam profile design. A conventional four-stroke turbocharged spark-ignition engine with a geometric compression ratio of 9.2 and a maximum power output of 112 kW was selected as the baseline engine. A validated one-dimensional engine simulation model was developed, incorporating in-cylinder pressure calibration using a turbulent combustion model for spark-ignition engines. Based on this model, Atkinson-cycle operation was implemented through intake camshaft optimization. Engine performance was evaluated over a wide range of speeds and loads, with particular emphasis on brake-specific fuel consumption (BSFC), torque, and overall fuel economy. Comparative analyses were conducted between the baseline engine and the optimized Atkinson-cycle configuration. The results indicate that intake valve timing optimization enables a reduction in average fuel consumption of approximately 2–3%, with an overall fuel consumption improvement of 2.5%. These findings demonstrate that Atkinson-cycle implementation through valve timing modification can effectively enhance fuel economy under the investigated operating conditions.

Keywords

Turbocharged SI Engine

Optimization cam profile

Fuel Economy

BSFC

Subjects