ABSTRACT The 7 th International Conerence on Automotive Engineering (ICAE-7) A Comparative Study o a used 4-Stroke Motorcycle Engine Perormance Using E85 and Gasoline 91 Tongchit Suthisripok, Thananchai Promjun and Assawin Rangron Automotive Engineering, College o Engineering, Rangsit University From the comparative study o the used 4-stroke motorcycle perormance using E85 and gasoline 91, it conirmed that E85 can be eectively used as an alternative uel i the engine is properly tuned and modiied. The motorcycle tested model was Honda Nice 100S whose carburetor was purposely designed or the use o gasoline. The motorcycle was tuned on dynamometer at the relative rich airuel ratio (λ) o 0.85 which theoretically resulted in the best power output. The required actual air-uel ratio o E85 is 9.87 while that o gasoline 14.7. Under the required uel-rich mixture or E85, the main nozzle size was increased by 1% to 0.85 mm rom the original size o 0.75 mm used or gasoline 91. The compression ratio and ignition timing remained unchanged. From the perormance test on the dynamometer, the Honda Nice 100S resulted similar perormance to the use o gasoline 91. The maximum power output was 5 hp @ 7563 rpm which was 16.7% lower than the use o gasoline 91, while the maximum torque was 6 N-m @ 5395 rpm which was 14.3% lower. In average, the consumption rate o E85 was 56.9 km/l, 11% more than that o gasoline 91 which was 63.9 km/l. Those were collected rom the road tests under conditions; the city road test at average speed 60 km/h and the long riding test at control speed 60 km/h or about 0 km/trip on the certain route. Though the heating value o E85 was 9.3 MJ/kg which was 31.8% lower than that o gasoline o 43 MJ/kg, the uel conversion eiciency ( ) o E85 was 17% higher. For the emission o burning E85, the measured quantities o carbon dioxide (CO) 0.71% vol. and o hydrocarbons (HC) 19 ppm were higher than those rom gasoline 91, 0.67 %vol CO and 10 ppm HC. All were much below the legislation limits, that is, < 4.5% vol. CO and 10,000 ppm HC. 1. INTRODUCTION The imbalance o world oil supply and demand, its price luctuation, and political instability in oil producers caused energy crisis and suered world economic. In addition, environmental problems, air pollution and global warming, have become urgent issues or all to concern. Emission rom burning ossil uels is a major attribution to air quality, mainly big cities dense in population and vehicles. Consequently, emission standard and requirements are needed to be more stringent and tighten. Since Thailand is an agricultural country and a net oil importer, biouels rom agricultural products should be seriously developed to be alternative source o energy. This will certainly create suiciency and sustainable economy in various sectors; agricultural, transportation, automotives and the related industries. Agricultural products like sugar cane and cassava are suitable eedstock or ethanol production. Cassava and molasses, the sugar mill byproduct, are oten surplus and exported in raw. The surplus will give higher value i they are ed to ethanol plants. Comparing to sugar cane, cassava is easier to grow and abandon to others, and more importantly, its longer harvest period. Typically, cassava is a eedstock or starch and animal eed, mostly or export. Though cassava is an economical eedstock or ethanol production, the production cost is higher than the others. Thereore, the ethanol production rom cassava totally depends upon the market price o ethanol. During the last quarter o 008, the ethanol market price was not high and the energy policy on alternative uels was not clearly deined, its demand was not likely to increase. The cassava harvest in the year 009/010 was not aected. In 010, the high price o resh cassava drove its harvest rom 5 mil ton to 33 mil ton. According to the national energy policy on alternative energy, the ethanol production is planned or 5-6 mil liter per day, that is, 3 mil liter per day o ethanol rom molasses and the balance o -3 mil liter per day rom cassava. [6-7] The ethanol producing rom cassava is currently more than 3 mil liter per day. Ethanol and gasohol, the blend o gasoline and ethanol, are proved to be used as an alternative uel in automobiles. At present, the premium gasoline 95 is gradually replaced by gasohol, E10 and E0, and inally phased out. Ethanol is a potential clean uel with similar characteristics to gasoline; the study o the use o highly blend ethanol uel like E85, 85%vol ethanol blended with 15% gasoline, in the 4-1
The 7 th International Conerence on Automotive Engineering (ICAE-7) stroke motorcycles is encouraged. Because motorcycles are necessary vehicles or low and middle incomes, over 0 million motorcycles consuming gasoline 91/95 have been used nationwide. Since the end o 006, the motorcycle sales became sluggish due to economic suering and lack conidence in overall market. Most importantly, oil price went up to higher than US$ 100 per bbl; this lessened the consumers buying power. [8] Typically, the 4-stroke motorcycle engines use carburetor to meter the appropriate uel low or the engine air low. The study o the use o E85 as an alternative uel in a used motorcycle - carburetor type will be conducted in 3 areas, that is, engine perormance, uel consumption and emission.. THEORY In spark ignition engines, the uel is normally mixed with air in the engine intake system. Combustion o the uel-air mixture reacted inside the engine cylinder controls engine power, eiciency, and emissions. I oxygen is suicient, a hydrocarbon uel can be completely oxidized. That is, the carbon in the uel is then converted to carbon dioxide CO, and the hydrogen to water H O. The stoichiometric proportion o uel and air is the theoretical proportion o enough oxygen or conversion o the all the uel into completely oxidized products. The stoichiometric air-uel ratio or uel-air ratio depends on uel composition. Fuel-air mixtures with more than or less than the stoichiometric air requirement can be burned. With excess air or uel-lean combustion, the extra air in unchanged orms appears in the products. Under the uel-rich mixtures, the incomplete combustion occurs because there is insuicient oxygen to oxidize uel carbon and hydrogen. The incomplete combustion products are a mixture o CO and H O and carbon monoxide CO and hydrogen H as well as nitrogen N. Because the composition o the combustion products is signiicantly dierence or uel-lean and uelrich mixtures, and because the stoichiometric air-uel ratio or uel-air ratios depends on uel composition, it is more inormative to deine the uel-air equivalence ratio,, or the relative air-uel ratio,, as ollows: A F actual 1 (.1) A F stoic For uel-lean mixtures: 1; 1 For stoichiometric: 1 For uel-rich mixtures: 1; 1 For gasolinec H 8 15, the stoichiometric combustion reaction is C8H15 11.75( O 3.776N ) 8CO 7. 5H O N (.) A and 14.7. For uel containing F stoic oxygen, ethanolc H 5 OH, uel oxygen is included in the oxygen balance between reactants and products. The stoichiometric combustion reaction is written as: CH 5OH 3( O 3.776N ) CO 3H O 11. 3N (.3) and A 9.0. The stoichiometric air-uel F stoic ratio o E85, a mixture o 85% ethanol and 15% gasoline, would thereore be about 9.87. Since the actual combustion process in incomplete, the uel energy supplied to the engine per cycle is not ully released as thermal energy in the combustion process. The combustion eiciency is less than unity and varies with the uel-air equivalence ratio. When insuicient air is present, lack o oxygen prevents the uel energy supplied rom being ully released. The ratio o the work produced per cycle to the amount o uel energy supplied per cycle that can be released in the combustion process is commonly used to measure engine s eiciency. This is called the uel conversion eiciency,, given by: W c (.4) m Q HV m Q HV where Wc is work per cycle, P is power, and m is mass o uel which can be replaced by the average mass low rate, For analysis, it is a normal practice in internal combustion engine to use the lower heating value at constant pressure, since the engine overall is a steady low device and the water in the exhaust is always in vapor orm. It is sometimes useul to separate out the eects o incomplete combustion by deining thermal conversion eiciency, t, as an eiciency which relates the actual work per cycle to the amount o uel chemical energy released in the combustion process: W P m. c t (.5) cm Q HV
The 7 th International Conerence on Automotive Engineering (ICAE-7) The uel conversion eiciency, thermal conversion and combustion eiciency are related by (.6) c t mixture becomes richer. Provided that the engine combustion process remains stable, other engine operating and design variables have little eect on combustion eiciency. [] 3. TESTS Figure.1 The eect o air-uel ratio on engine power and emission. [9] Exhaust gas composition depends upon the relative proportions o uel and air ed to the engine, uel composition, and completeness o combustion. In practice, the exhaust gas o an internal combustion engine contains complete combustion products; CO and H O, as well as incomplete combustion products; CO, H, unburned hydrocarbons, and soot. Under uel-rich operating conditions, the amounts o incomplete combustion productions become more substantial since oxygen is insuicient to complete combustion inside the cylinder. For spark ignition engines, Since the motor cycle tested, Honda Nice 100S, was used over 30,000 kilometers, the engine conditions must be thoroughly inspected: 1. Fuel system 1.1 Fuel tank - inspect any rust and /or leak 1. Fuel line - inspect crack, i any, such lines must be replaced.. Carburetor - cleanse deposits/soot 3. Air ilter - change to the new air ilter 4. Transmission system - thoroughly inspected the system; chain stretch and sprockets wear, to assure that all were in good condition. Those are normally requiring periodic replacements, 5. Brake system - inspect brake conditions; brake pad thickness. Ater repeated use, the brake pads suraces wear away, the pad must be replaced periodically. 6. Lubrication system - thoroughly inspected. I any leak or seep was ound, it must be ixed. Then, the brand new lubrication oil will be used. 3.1 TEST EQUIPMENTS The test equipments were used are as ollows: 1. The used 4-stroke motorcycle, Honda Nice 100S. Dynamometer or dyno 3. MoTec Lambda ( or Relative Air/Fuel Ratio) Meter 4. Automotive Emission Analyzer OPUS 0 5. Test Fuels - Gasoline 91 and E85 6. Protune Compression Tester Kit 7. Speedometer - MAXR Racing Sports 8. Oxygen Sensor Figure. Fuel mileage versus average speed eect o ethanol on 008 Nissan Rogue [10] the combustion eiciency operating at lean equivalence ratio is usually in the range o 95 to 98%. For richer mixtures operating condition, lack o oxygen prevents to completely oxidize uel carbon and hydrogen. The eiciency steadily decreases as the Figure 3.1 Dynamometer 3
The 7 th International Conerence on Automotive Engineering (ICAE-7) Figure 3. MoTec Lambda ( or Relative Air/Fuel Ratio) Meter Figure 3.6 Speedometer - MAXR Racing Sports Figure 3.3 Automotive Emission Analyzer OPUS 0 Figure 3.4 Test Fuels- Gasoline 91 and E85 Figure 3.7 Oxygen Sensor 3. PERFORMANCE TEST ON DYNAMOMETER 1. Tight the motorcycle tested irmly on the dynamometer, and then calibrated the engine speed (rpm).. Start the engine, then ull accelerated at the set gear, the nd gear selected or this test. 3. Cut o the transmission system by irmly holding the hand clutch, so both tires were rolling reely. Data are then processed and resulted in torque and power output corresponding to speeds. 4. Apply brake and turn o the engine. Figure 3.5 Protune Compression Tester Kit Figure 3.9 Perormance test on Dynamometer Torque and Power 4
The 7 th International Conerence on Automotive Engineering (ICAE-7) 3.3 FUEL CONSUMPTION RATE TEST There were -test conditions - the long-riding at the controlled speed o 60 km/h on the certain route o about 0-km/trip and the city road test at the average speed o 60 km/h. 1. City road test at the average speed o 60 km/h The test data were collected rom daily riding in the city at the average speed o 60 km/h. The normal route was along the Phraholyothin road to Rangsit University and around the area.. Long riding test at the control speed o 60 km/h The long riding test was perormed on the local road around the Lakhok district during 09:00-1:00 hr. During that period, the traic was light and the weather was sunny and breeze. Each trip was about 0 km and the speed was controlled at 60 km/hr. 3.4 EMISSION MEASUREMENT 1. Turn on the emission test instrument and select the 4-stroke engine mode.. Start the engine and then insert the oxygen sensor right in the middle o its exhaust pipe. 3. Once data on the reading screen are stable, print out the recorded data. 4. Remove the sensor and turn o the engine. Figure 3.10 Emission Measurement 4. RESULTS Once the used 4-stroke motorcycle tested, Honda Nice 100S was thoroughly inspected and well set, the comparative tests; engine perormance, consumption rate, and emission, between the use o gasoline 91 and E85 were conducted. The test steps were as ollows: 1. Fine tuning the motorcycle on dynamometer at the uel-rich mixture (or ) o 0.85 which gives the best perormance or gasoline engine. (see Fig..1). Perorm the road tests long riding and city riding 3. Periodically measure emission 4. Ater riding or about 4,000 km, then change uel to E85 and repeat step 1 to 3. 4.1 PERFORMANCE TEST RESULTS When ueled with gasoline 91, the maximum torque was 7 N-m@541 rpm and the maximum power output was 6 hp at 6330 rpm. For E85, the stoichiometric air-uel ratio is about 9.87 and it was 14.7 or gasoline. The combustion condition o E85 was operated in uel-richer mixture than that o gasoline 91. Upon the engine tuning at the relative rich airuel ratio ( ) o 0.85 which theoretically gave the best power output, the main nozzle size was increased by 1% to be 0.85 mm rom its original size o 0.75 mm used or gasoline 91. The compression ratio and the ignition timing remained unchanged. From the perormance test on dynamometer, the maximum torque was 6 N-m @ 5395 rpm and the maximum power output was 5 hp @ 7563 rpm. When ueling with E85, the engine perormance dropped about 16.7% as shown in Fig. 4.1. Though E85 is an oxygen-containing uel, there is insuicient oxygen to ully oxidize uel under such uel rich mixture condition. Besides that, but it is more diicult to vaporize because o having higher heat o vaporization; 840 kj/kg or ethanol. To improve the engine perormance, the ignition timing can still be advanced within 5-10 O. Theoretically, E85 gives higher power output as its combustion is better than the use o gasoline 91. When burning ethanol, temperature around the intake area is low and denser and higher intake volume was orced into the cylinder. Thereore, the volumetric eiciency is higher and result in better engine perormance. From the perormance test data, the calculated uel conversion eiciency o E85 was 17% higher than that o gasoline 91 as shown in Table 4.1. It proves that E85 is an eective alternative uel or the 4-stroke motorcycles i the engines are properly modiied and tuned. 5
The 7 th International Conerence on Automotive Engineering (ICAE-7) Figure 4.1 Torque and Power Output o the used 4-stroke motorcycle tested on Dynamometer - Gasoline 91 and E85 Table 4.1 Comparison o uel conversion eiciency between gasoline 91 and E85 Gasoline 91 E85 Density* @ 15 O C, kg/m 3 0.7381 0.7747 Average mass low rate m, kg/s 3 3 0.7381 10 0.7747 10 Lower Heating Value Q, MJ/kg 43 9.3 LHV Power Output** ( P max ), hp 6 5 Fuel conversion eiciency.17,ron 91 1, RON 91 Note: * From Bangchak Petroleum Public Co. Ltd. (BCP the oil reiner) ** Perormance test data on dynamometer Calculation basis: Fuel volume 1 liter and 1 hp = 0.746 kw 4. FUEL CONSUMPTION RATE RESULTS The uel consumption rate was tested on both the city riding at the average speed o 60 km/h and the long riding at the control speed o 60 km/h about 0-km/trip on the ixed route. For each uel type, the -condition road tests were in total about 4,000 km. Data collected rom each test set o uel used, gasoline 91 and E85, was graphically displayed in Fig. 4.. Under the properly engine tuning and modiying, (d) and () in Fig. 4., the average consumption rate o E85 rom both riding tests was 11% more than that o gasoline 91. E85 has heating value o 9.3 MJ/kg which was 3% lower than that o gasoline 91. As well, the stoichiometric air-uel ratio o gasoline and E85 is 14.7 and 9.84. When ueling with E85, it is certainly required much uel-richer mixture condition. Upon the engine tuning on dynamometer at the best given power output ( ) o 0.85, its main nozzle size was increased rom 0.75 mm to 0.85 mm. Once the engine was properly tuned up and modiied, it s riding perormance with E85 uel was as comortable as ueling with gasoline 91. There was no diiculty in engine starting except that in the cold weather, it needed to choke the engine. 6
The 7 th International Conerence on Automotive Engineering (ICAE-7) Figure 4. Comparison o uel consumption rate o the used 4-stroke motorcycle - Gasoline 91 and E85 4.3 Emission Test Results Beore and ater the engine tuning on the dynamometer at the relative rich air-uel ratio ( ) o 0.85 gave the best power output, the emission in the exhaust o burning both gasoline 91 and E85 were periodically measured. The emission contents, carbon monoxide (CO) and hydrocarbon (HC), measured rom both uels were compared graphically in Fig. 4.3 and 4.4. Beore enginetuning at the o 0.85, the amount o carbon monoxide in the exhaust o burning gasoline 91 was 1.4 %vol and then reduced to 0.67 %vol ater tuning the engine at the best given power output ( ) o 0.85. The measured amount was much lower than the legislation limit o 4.5 %vol. When ueling with E85, the engine was tuned at the best given power output o 0.85; the required air-uel ratio was much richer. As a result, the amount o the carbon monoxide (CO) and hydrocarbon (HC) in the exhaust were very high as 5.6 ppm and 1690 ppm, respectively. Though E85 can be used to uel the engine, its combustion condition was not yet good and resulted in high amounts o incomplete combustion products, CO and HC, in the exhaust. The motorcycle was then again ine tuned and adjusted the main nozzle size by +1%, rom 0.75 mm original used or gasoline to 0.85 mm, the measured amount o carbon monoxide and o hydrocarbon decreased drastically to 0.71 %vol and 19 ppm. However, both products were higher than those in the exhaust o the gasoline 91 but much lower than the legislation limits o <4.5 %vol or CO and 10,000 ppm or HC. As the instrument or measuring nitrogen oxide (NOx) was not available, there was no data or the amount o nitrogen oxide in the exhaust rom both uels. Since the operating condition o gasoline engines was mostly in uel-rich mixture, the NOx caused much less problem than in the uel- lean mixture. 7
The 7 th International Conerence on Automotive Engineering (ICAE-7) Figure 4.3 Comparison o the amount o carbon monoxide (CO) in exhaust o the used 4-stroke motorcycle Gasoline 91 and E85 Figure 4.4 Comparison o the amount o hydrocarbons (HC) in exhaust o the used 4-stroke motorcycle Gasoline 91 and E85 5. CONCLUSION This study conirmed that E85 is an eective alternative uel or used 4-stroke motorcycles i the engine conditions are properly tuned and modiied. For practical purposes, the engine modiication must be simple and cost eective. The motorcycle tested was Honda Nice 100S whose carburetor was purposely designed or the use o gasoline. To achieve the optimum perormance condition or the use o E85, the engine was tuned up on dynamometer at the relative uel rich mixture ( ) o 0.85 which theoretically gave the best power output. The stoichiometric air-uel ratio o E85 is 9.87 while that o gasoline is 14.7. As such required uelricher mixture condition or E85, the main nozzle size was increased 1% rom its original use o 0.75 mm to 0.85 mm while maintaining the compression ratio and the ignition timing. When ueling with E85, the achieved perormance tests on dynamometer 8
The 7 th International Conerence on Automotive Engineering (ICAE-7) reduced by 16.7% or the power output and 14.3% or torque. From the road tests, the average consumption rate o E85 was 11% more. For emission measurement o burning E85, the amount o carbon monoxide (CO) and hydrocarbon (HC) were 0.71 %vol and 19 ppm, respectively. Those were higher than in the exhaust o burning gasoline 91. However both contents were much lower than the legislation limits, <4.5 %vol or CO and <10,000 ppm or HC. Under the properly tuned and modiied condition or E85, the riding perormance was smooth and the engine can be started without any problem. In cold weather, it needs choke to ease the engine starting. In case o no use longer than 3 days, it also needs choke to assist the engine starting. From the use o E85, it experienced that lubricating oil became much less viscous at the same changing distance o about 4,000 km. Like gasoline, lubricating oil is petroleumbase product. When ueling with E85, a mixture o 85% alcohol and 15% gasoline, the reaction o lubricating oil and such uel resulted dierently. For E85 use, the changing schedule o lubricating oil would be shorter. Because o ethanol s strong solvent properties, components; rubber, plastic, and seal, exposed to E85 must be requently checked. For conirmation on both issues, more tests are needed. Since E85 has higher octane number o 105, it is possible to advance the ignition timing within 5-10 O or better perormance. Then the consumption rate and emission must be retested. Ethanol rom Cassava - Fiscal Year 009. http://03.156.104.73/~dip_cms/joomla_1.5.1 4-x/download/report5.pd 7. Department o Alternative Energy Development and Eiciency, Ministry o Energy, 010. Ethanol Feedstock Estimate, Jan. 4, 010. http://www.dede.go.th/dede/ileadmin/usr/bers/ gasohol_documents/gasohol_009/demand_s upply_new401010.pd 8. Car Manuacturing, domestic Sales and Exports rom Thailand, Statistics o Sales and Exports rom 1993 onwards. http://www.thaiwebsites.com/cars-thailand.asp 9. Technical column, Correct Air/Fuel Ratio, Apr. 0, 006. http://www.quadparts.co.za/orum/viewtopic.ph p?p=41&sid=5abbd89b7486c663e4dc9 11d976 10. Wertheimer, H, More Ethanol Equals More CO Emissions, Energy Tribune, Oct. 13, 009, http://www.energytribune.com/articles.cm?aid =437 7. ACKNOWLEDGEMENTS The study was conducted successully with the great supports rom Bangchak Peteroleum Public Co. Ltd., and A.A.S Autoservice Co. Ltd., and College o Engineering, Rangsit University. The Bangchak Peteroleum Company (BCP) provided the quality test uels, gasoline 91 and E85. The A.A.S Autoservice Company gave valuable technical advice along with standard testing equipment, dynamometer. 6. REFERENCES 1. Promjun, T. and Rangron, A., 008. A Comparative Study o 4-Stroke Motorcycle Engine Perormance using E85 and Gasoline 91", Thesis (B.Eng. Automotive Engineering), College o Engineering, Rangsit University, Thailand.. Heywood, J.B., 1988. Internal Combustion Engine Fundamentals, McGraw- Hill, Inc. 3. Cengel, Y.A. and Boles, M.A.., 007. Thermodynamics: An Engineering Approach, 6 th Edition, McGraw Hill, Inc. 4. Plint, M. and Martyr, A., 001. Engine Testting Theory and Pratice, nd ed., Butterworth-Heinemann. 5. Pulkrabek, W.W., 1997. Engineering Fundamentals o the Internal Combustion Engine, Prentice-Hall International, Inc. 6. Department o Industrial Promotion, Ministry o Industry, 009. Feasibility Study o 9