To carry out the tests, a four-stroke Honda engine, OHV, single-cylinder of 163 cm3, maximum power of 5.5 CV/3,600 rpm and net power of 4.8 CV/3,600 rpm was used. The maximum torque of 1.10 kgf.m/3,600 rpm and net torque of 1.05 kgf.m/2,500 rpm. The oil capacity in the crankcase is 0.6 liters and the fuel (gasoline) capacity is 3.1 liters. The idle rotation is . This engine model does not have a lube filter.
I was used the manufacturer recommended lubricant ( genuine Honda SAE 10W-30 SJ JASO MA semi-synthetic).
This engine was mounted on a bench where it was coupled to an alternator through pulleys and belt, to simulate the daily workload, as shown in Figure 1.
To verify if the alternator was performing the function of simulating a workload, a rotation test was carried out with and without the alternator, that is, the engine was put to work coupled and without being coupled to the alternator.
As the engine was purchased new, specifically for this project, it was necessary to go through the break-in process, according to the owner's manual (HONDA, 2015) , with a 20-hour operation. At the end of the break-in, the engine was overhauled, with the removal of the used lubricant, which was discarded, and disassembled for internal cleaning. After the overhaul, with the engine mounted, the specific cycles for the work were started.
In order for the lubricant to have the same demand in all tests, with the different mixtures of fuel and contaminants, the rotation was predetermined and fixed.
The determination of a rotation around 2000 rpm is due to the fact that this is the rotation where the vehicle has a moderate fuel consumption and a good performance.
To achieve this rotation, regulation of the idle speed through its screw was used. The engine was started up with clean gasoline and the adjustment was made, which was not changed until the end of all the tests.
3.1 BENCH INSTRUMENTATION
The workbench has an hourmeter and tachometer clock, and the reading was taken alternately, that is, with the engine off, the clock shows the hours accumulated so far and when you press the selector button, it shows the partial hours worked. When the engine is running, the watch shows the engine speed and pressing the selector switches it to the split hours worked.
The hourmeter/tachometer clock operates on the energy induced by the spark plug cable. This clock has two wires and to be installed, just wind one of the wires around the spark plug cable, making five turns and the other wire must be connected to the motor frame, which is the negative.
Figure 2 shows the detail of the assembly of the hourmeter wire on the engine spark plug cable.
The hourmeter makes it possible to configure the type of engine to which it is connected, that is, whether the engine is two or four strokes and the number of cylinders the engine has. In this case it was configured as a four-stroke, one-cylinder engine only.
3.2 TEST STEPS – CYCLES
The duration of each cycle was defined based on the regulatory speed of an average city, which is between 40 and 50 km/h. Honda's stationary engine is similar to a motorcycle engine, where lubricant changes must be made every 4,000 km. According to the motor vehicle manuals, this change interval of 4,000 km is based on a normal use system, but if the use is severe, this interval should be half this mileage, ie 2,000 km.
Thus, as the engine is on a bench, coupled to an alternator, the severe work regime was adopted. Based on these data, converting kilometers into hours, we find 40 hours, which was the duration of each cycle. Equation (1) presents the calculation made to find out how many hours there should be in each cycle.
The tests were with “clean” gasoline and with a contaminant, namely kerosene, ethanol and thinner, in percentages of 5, 10, 15 and 20% in each cycle, totaling sixteen tests, four with each contaminant.
All fuel measurements were made using a test tube, pipette and beaker. These glassware were used in order to make the volumes as accurate as possible.
The cycles lasted for 40 hours.
The engine was filled with lubricant and fuel and started to run. After completing the forty-hour cycle, the engine was turned off and the lubricant sample removed, as shown in Figure 3.
The samples were taken right after turning off the engine, so the engine was still hot and the sample would also be very homogeneous.
A 20 ml disposable syringe and hose were used, and the sample taken was approximately 300 ml, so that all tests could be performed.
After taking the sample, the engine crankcase was drained and the engine was disassembled for a very thorough internal cleaning, removing the rest of the used lubricant from the crankcase and cleaning the cover of this crankcase.
The rest of the lubricant used, after taking the sample, was packed in plastic containers and then discarded in workshops that carry out oil changes and give the proper destination to this lubricant, thus contributing to the non-contamination of the environment.
For this procedure, it was necessary to remove the motor from the bench, place it on a table and start disassembly. The next step is to remove the pulley, using a pulley puller and only then start the disassembly of the crankcase cover, which is fixed with eight screws.
For this disassembly and cleaning procedure, absorbent paper was used, avoiding the use of cloth because this releases fragments or lint that is harmful to the engine. Then, the engine was assembled again, filled with new lubricant and gasoline with a new percentage of contamination, the partial hour meter was reset and a new cycle started.
This cleaning and sampling procedure was the same for all cycles and all contaminants.
After all the cleaning, the engine was reassembled, the pulley was installed again and the engine returned to the bench. At this time, it was filled with new lubricant (not in use) and the fuel tank was filled with a new percentage of mixture.
When running the engine, the hourmeter/tachometer begins to measure the running time with the predetermined amount of fuel and also marks the engine speed.
When starting the engine, it was waited 10 minutes to ensure that the engine had stabilized working conditions, such as ideal temperature, thus guaranteeing the same parameter for all tests.
After 10 minutes, a film of about 90 seconds of the tachometer was made. Then, all rotation values were recorded, second by second, until reaching sixty readings. With these values, rotation graphs were plotted for analysis.
3.3.1-PQA (Particle Quantifier Analyzes)
For this test, the ferrous particle monitor from Kittiwake Developments Ltda was used as shown in Figure 4.
This Monitor examines the sample through an inductive field, which when detecting the presence of magnetic materials presents the result in the form of a dimensionless index called the PQ index. This index is directly related to the amount of ferromagnetic materials contained in the oil, very useful information in the construction of trend graphs.
After a sample homogenization step, using a pipette, 2 ml of lubricant was placed in each container of the PQA Monitor, which then receives the lid and identification.
3.3.2 -Spectrometer of infra-red
Infrared spectrometry was performed according to the specifications (SPECTRO SCIENTIFIC, 2013 and SPECTRO SCIENTIFIC, 2014) . With the apparatus we obtained the measurements of Oxidation, Sulfatation, Nitriding and TBN (Total Acid Number).