Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel Full Length Article Experimental optimisation comparison of detonation characteristics between leaded aviation gasoline low lead and its possible unleaded alternatives Thanikasalam Kumar a,c, ⁎ , Rahmat Mohsin a , Zulkifi Abd. Majid a , Mohammad Fahmi Abdul Ghafr b , Ananth Manickam Wash a a UTM-MPRC Institute for Oil and Gas (IFOG), Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia (UTM), 81300 Skudai, Johor, Malaysia b Department of Aeronautical Engineering, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), 86400 Parit Raja, Johor, Malaysia c Crime Investigation Division, North Johor Bahru Police District, Royal Malaysia Police, 81300 Skudai, Johor, Malaysia ARTICLE INFO Keywords: Leaded aviation fuel Unleaded motor fuel Response surface method Detonation Optimization Lycoming O-320 ABSTRACT Federal Aviation Administration’s twenty years of research with two-hundred unleaded blends has not found a “drop-in” unleaded replacement for aviation gasoline 100 low lead, a specifcally formulated fuel for usage in naturally aspirated aircraft engines and contains tetraethyl lead additive to assist on detonation. Tetraethyl lead emission from piston aircrafts can cause serious health impacts and is a human carcinogenic substance. This research optimised the detonation efciency of 14 aviation/motor fuels/blends. Type of fuels/blends and engine speed were chosen as input parameters. Relative detonation index was the output parameter. The engine speed was difered from 2000 to 2700 and the fuels were changed at fourteen levels. The design matrix consisted of 98 runs and was based on one factor response surface methodology. Analysis of variance was done on the design model to authenticate the signifcance. Engine speed and type of fuel were set to be in range while relative detonation index was minimised. Confrmation experiment was performed to check and confrm the actual and predicted outcomes. Results showed that at 2300 engine speed, Research Octane Number 98 fuel exhibited the best desirability of 0.759 among all fuels/blends with 57.153% of relative detonation index. The outcome re- vealed that tetraethyl lead addition into the aviation gasoline low lead can be eliminated. 1. Introduction Motor gasoline (MOGAS) remains as a replacement to gasoline with lead in the form of tetraethyl lead (TEL) ever since 1964 after Experimental Aircraft Association (EAA) started evaluating it [1,2]. Very frst departure of a Cessna 150 in 1982, equipped with Continental 0–200 engine displayed fantastic outcomes. Nevertheless, for MOGAS to be utilized in airplanes, engine alteration; authorized through Sup- plemental Type Certifcate (STC) endorsement released by the Federal Aviation Administration (FAA), is mandatory. Such alterations, the al- ternative gasoline pumps and gasoline line distribution techniques guarantee the plane is suitable using MOGAS. Collectively, to date, https://doi.org/10.1016/j.fuel.2020.118726 Received 5 April 2020; Received in revised form 13 June 2020; Accepted 12 July 2020 Abbreviations: ANOVA, Analysis of Variance; AOPA, Aircraft Owners and Pilots Association; AP, Adequate Precision; ASTM, American Society for Testing Materials; AVGAS, Aviation Gasoline 100 Low Lead; BHP, Brake Horsepower; BMEP, Brake Mean Efective Pressure; BSFC, Brake-Specifc Fuel Consumption; BTHE, Brake Thermal Efciency; CAA, Clean Air Act; CC, Cubic Inches; CO, Carbon Monoxide; CO 2 , Carbon Dioxide; CRC, Coordinating Research Council; EAA, Experimental Aircraft Association; EGT, Exhaust Gas Temperature; EPA, Environmental Protection Agency; FAA, Federal Aviation Administration; FOE, Friends of the Earth; GAMA, General Aviation Manufacturer Association; Lycoming IO-360-DB, Fuel Injected (I) Horizontally Opposed (O) 360 CC (DB) series engine; Lycoming IO540-K, Fuel Injected (I) Horizontally Opposed (O) 540 CC (K) series engine; Lycoming O-320, Carburetted Piston Horizontally Opposed (O) 320 CC engine; Lycoming TIO- 540-J2BD, Turbocharged (T) Fuel Injected (I) Horizontally Opposed (O) 540 CC (J2BD) series engine; MMT, Methylcyclopentadienyl manganese tricarbonyl; MOGAS, Motor gasoline; MON, Motor octane number; NAAQS, National Air Ambient Quality Standard; NO x , Nitrogen Oxides; Ns, Engine Speed; PAFI, Piston Aviation Fuels Initiative; PN, Performance Number; R, Regression; RDI, Relative Detonation Index; RON, Research Octane Number; RPM, Revolution Per Minute; RSM, Response Surface Methodology; STC, Supplemental Type Certifcate; TEL, Tetraethyl Lead; UAT ARC, Unleaded AVGAS Transition Aviation Rulemaking Committee; UHC, Unburned Hydrocarbon; UTM, Universiti Teknologi Malaysia; WHO, World Health Organization ⁎ Corresponding author at: Crime Investigation Division, North Johor Bahru Police District, Royal Malaysia Police, 81300 Skudai, Johor, Malaysia. E-mail address: insp466@hotmail.com (T. Kumar). Fuel 281 (2020) 118726 Available online 11 August 2020 0016-2361/ © 2020 Elsevier Ltd. All rights reserved. T