Exhaust Tuning of an Internal Combustion Engine by the Combined Effects of Variable Exhaust Pipe Diameter and an Exhaust Valve Timing System

Abstract

Changes to engine geometry and specifications can produce better torque, power, volumetric efficiency and more. The technique known as wave tuning can lead to better engine torque and power. This paper focuses on increasing the engine torque by improving the exhaust fluid flow through the exhaust manifold. Phasing and intensity of the pressure waves in the exhaust manifold have significant effects on scavenging, valve overlapping and pumping losses. In this research, individual and combined effects of variable exhaust runner diameter and exhaust valve timing on the fluid flow from exhaust of the engine are studied using computer simulation. An engine simulation software, Ricardo Wave, is utilized in this research. The analysis is conducted on a 1-D model of a KTM 510 cc single cylinder, four-stroke Sl engine. The data gathered shows that varying only the exhaust pipe diameter continuously with speed yields an average of 4.23% improvement in torque from the original engine model. However, due to practical constraints, the diameter is limited to vary in three steps (36 mm, 45 mm and 60 mm). This has reduced the average improvement of torque to 3.78%. Varying the valve timing alone gains an average of 1.94% improvement in torque. Varying both the exhaust pipe diameter in three steps and the exhaust valve timing yields an average of 4.69% improvement in torque. This average is conducted over the engine speed ranges from 2000 to 11,000 rpm.

Elucidating Optimal Exhaust Manifold Divergence and Temperature Distribution in Improving Low-End Engine Speed Performance

“…As a result, the configuration of the exhaust manifold is critical in determining the pressure, velocity, and overall efficacy of the exhaust system. [11] An exhaust manifold's diameter may affect an engine's torque, according to Sawant et al, [12]. Lower rpm torque is improved by smaller diameters, whereas higher revolutions per minute torque is improved by bigger diameters.…”

Flow characterisation in an exhaust manifold of a single-cylinder internal combustion engine (ICE)

“…The shape of the exhaust manifold and the collector geometry is crucial for tuning of the torque curve in a multiple cylinder ICE [4]. Previous studies have shown that pipe diameter and valve timing for the exhaust system play a prominent role in overall engine performance [5]. Besides, the sharp elbows and long exhaust pipe was found to increase the exhaust backpressure [3], that is directly influencing the performance of the engine.…”