This paper presents the enhancement of the thermophysical properties (thermal conductivity and viscosity) of engine oil using nano-lubricant additives and a characterization of tribological behaviour in terms of sliding contact interfaces (piston ring assembly) in automotive engines. Al₂O₃, TiO₂ and Al₂O₃/TiO₂ hybrid nanoparticles were suspended in commercially available engine oil (5W-30) in a concentration of 0.25 wt% for formulating nano-lubricants. The sizes of Al₂O₃ nanoparticles were within the range 8–12 nm while the TiO₂ nanoparticles used had a size of 10 nm. The tribological experiments were performed using a tribotester to simulate the sliding reciprocating motion of the piston ring/cylinder liner interface in an engine. The performed tribological tests were all carried out under varying speeds, loads and sliding distances. The experimental results showed that nano-lubricant additives enhanced the thermophysical and tribological properties. The thermal conductivity of lube oil was measured by the 3ω-wire method. Nano-lubricants provide low kinematic viscosity and an increase in the viscosity index by 2%. Meanwhile, thermal conductivity was enhanced by a margin of 12–16% for a temperature range of 10–130 °C facilitating the dissipation of frictional heat and maintaining engine oil properties, as compared with commercial lubricants. The tribological tests showed a minimization of the friction coefficient and wear rate of the ring by 40–50% and 20–30%, respectively. According to the results, nano-lubricants can contribute to improving the efficiency of engines and fuel economy in automotive engines.

Emission legislation has become progressively tighter, making the development of new internal combustion engines very challenging. New engine technologies for complying with these regulations introduce an exponential dependency between the number of test combinations required for obtaining optimum results and the time and cost outlays. This makes the calibration task very expensive and virtually impossible to carry out. The potential use of trained neural networks in combination with Design of Experiments (DoE) methods for engine calibration has been a subject of research activities in recent times. This is because artificial neural networks, compared with other data-driven modeling techniques, perform better in satisfying a majority of the modeling requirements for engine calibration including the curse of dimensionality; the use of DoE for obtaining few measurements as practicable, with the aim of reducing engine calibration costs; the required flexibility that allows model parameters to be optimized to avoid overfitting; and the facilitation of automated online optimization during the engine calibration process that eliminates the need for user intervention. The purpose of this review is to give an overview of the various applications of neural networks in the calibration of spark-ignition engines. The identified and discussed applications include system identification for rapid prototyping, virtual sensing, use of neural networks as look-up table surrogates, emerging control strategies and On-Board Diagnostic (OBD) applications. The demerits of neural networks, future possibilities and alternatives were also discussed

This paper reviews the serviceability of hydrous ethanol as a clean, cheap and green renewable substitute fuel for spark ignition engines and discusses the comparative chemical and physical properties of hydrous ethanol and gasoline fuels. The significant differences in the properties of hydrous ethanol and gasoline fuels are sufficient to create a significant change during the combustion phase of engine operation and consequently affect the performance of spark-ignition (SI) engines. The stability of ethanol-gasoline-water blends is also discussed. Furthermore, the effects of hydrous ethanol, and its blends with gasoline fuel on SI engine combustion characteristics, cycle-to-cycle variations, engine performance parameters, and emission characteristics have been highlighted. Higher water solubility in ethanol‑gasoline blends may be obviously useful and suitable; nevertheless, the continuous ability of water to remain soluble in the blend is significantly affected by temperature. Nearly all published engine experimental results showed a significant improvement in combustion characteristics and enhanced engine performance for the use of hydrous ethanol as fuel. Moreover, carbon monoxide and oxides of nitrogen emissions were also significantly decreased. It is also worth pointing out that unburned hydrocarbon and carbon dioxide emissions were also reduced for the use of hydrous ethanol. However, unregulated emissions such as acetaldehyde and formaldehyde were significantly increased.