Improvement of performance by 2-Step variations of intake runner length and intake valve timing in the induction system of a SI engine

Abstract

In this research, intake runner length, and valve timing are varied individually and simultaneously over a range of values to capitalize the induction pressure waves to boost volumetric efficiency. 1-D model of the stock engine built in Ricardo Wave software is validated with 90% accuracy against experimental test results. The volumetric efficiency of the engine is boosted by an average of 3.2% over the speed range of the engine when infinitely variable runner lengths are used. When only two variations in runner length are used, the volumetric efficiency has boosted by around 1.4% on average. On the other hand, when infinitely variable valve timings along with two variations in runner lengths are used, the volumetric efficiency has boosted by an average of 7.78 %. Due to the existence of two different runner lengths, the span of variations required in valve timing is reduced further optimizing the volumetric efficiency. However, to ensure feasibility of the design, manufacturing, assembly and operation, it is better to use only two valve timings. The co-presence of only two different runner lengths and two different valve-opening timings, the average boost of 5.40 % in volumetric efficiency throughout the operating speed range of the engine is encountered.