Design of intake system of an internal combustion (IC) engine is critical to improve the performance of the engine. Induction pressure waves (compression and rarefraction waves) are created in the intake runner due to valve operations. If the intake runner is tuned correctly, a compression wave can boost the intake air flow improving the volumetric efficiency which increases the torque and power of the engine. This paper varies the intake runner diameter and valve timing individually, and then together to achieve optimum volumetric efficiency. A single-cylinder, four-stroke spark-ignited 510 cc naturally aspirated engine was used for the analysis. Simulations were carried out using engine simulation software Ricardo Wave to find the effect of intake valve diameter and timing on the engine performance. A chassis-dyno test was made on the engine to know its factory state performance and compared the performance with the simulation data which proved to be within ± 12%. The differences were mainly due to the losses from the engine shaft to the wheel of the car standing on the roller of the chassis dyno, which were not considered in the simulation. Gains achieved upon combined effects of variation of both intake diameter and valve timing across the engine speed range were appreciable. It was observed that when only intake diameter was varied, the improvement in volumetric efficiency was approximately 6%. Similarly, when only intake valve timing was varied, around 3% improvement was seen. However, upon varying both intake valve diameter and timing for each speed simultaneously, an average increment of 7% was noted. Moreover, this integration also resulted in reduced range of variations of diameter and timing compared to individual range of variations required by the each, thus the associated complications such as packaging and weight of the assembly was also found to be reduced.