Numerical/Experimental Studies on Performance at Low Engine Speeds: A Case study Downsized Iranian National Engine (EF7)

Engine downsizing is a trusted method to reduce fuel consumption and pollution emitted from internal combustion engines. In this method, engine displacement volume is reduced while maintaining the same power/torque characteristics. However, there still exist several limitations to utilize this technology. In this paper, the naturally aspirated type of Iranian national engine (EF7-NA) for a possible downsized version is investigated. A one-dimensional engine model equipped with a zero-dimensional two-zone combustion sub-model was developed and validated via experimental results for both natural aspirated and turbocharged engine types. Then experimental and numerical studies were carried out for the primary concept, deactivation of one cylinder besides using a turbocharger. To overcome the concept shortages, especially in lower ranges of engine speed, numerical studies were extended. Deployment of several turbochargers with different performance maps and different valve timing via a dual continuous variable valve timing (CVVT) system were investigated. The results showed that there is a feasible method for EF7 engine downsizing via a 3-cylinder type equipped with a modified turbocharger and valve timing. The maximum difference between base-engine and downsized version torque is about 7% in low engine speeds.