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Open AccessArticle

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

Department of Mechanical Engineering and Engineering Science, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA
School of Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia
Author to whom correspondence should be addressed.
Energies 2018, 11(6), 1545;
Received: 21 April 2018 / Revised: 3 June 2018 / Accepted: 5 June 2018 / Published: 13 June 2018
(This article belongs to the Section Energy Fundamentals and Conversion)
PDF [15525 KB, uploaded 13 June 2018]


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. View Full-Text
Keywords: engine; exhaust tuning; rarefaction wave; pressure; torque engine; exhaust tuning; rarefaction wave; pressure; torque

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Sawant, P.; Warstler, M.; Bari, S. Exhaust Tuning of an Internal Combustion Engine by the Combined Effects of Variable Exhaust Pipe Diameter and an Exhaust Valve Timing System. Energies 2018, 11, 1545.

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