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Tests of mechanical losses are conducted on a dynamic engine dyno, where the measurement of torque needed for a combustion engine running under set conditions is possible. The aim of the test is to define the influence of the engine oil in use on the engine’s mechanical efficiency and the reduction of frictional losses. The choice of engine oil also influences the engine’s fuel consumption – and thereby CO2 emissions. The results permit improvement of the lubricating properties of engine oils through quantification of the influence of individual oil additives on the friction within the engine.
Tests of fuel dilution of engine oil and the resulting influence on wear of individual engine components are conducted on an engine dyno. In modern Diesel engines, such dilution phenomena most often occur due to frequent active regenerations of the particulate filter (DPF). During testing, through control of the number of DPF regenerations, a designated value of fuel concentration in engine oil is maintained, which allows evaluation of the negative influence of phenomena linked to fuel dilution of engine oil on engine components. During such tests, oil samples are subjected to regular chemical analyses in order to determine the level of dilution, as well as the content of metallic elements.
Tests determining an oil’s propensity to form sediments on mechanical parts of the engine – for example, the compressor housing – or its influence on the wear of lubricated elements, for example the camshaft or the driveshaft. Elements tested can be weighed (mass increase due to deposits formed; mass loss due to material wear) and also subjected to both visual analyses and meteorological measurements, before and after the test. Oil validation tests, for example, durability tests (test duration approx. 1000 h), cold start, efficiency of the lubricating system, allow all engine components whose durability is influenced by the engine oil to be tested. For modern turbocharged engines, oil validation tests are often performed by determining the quantity of sediments formed on the compressor housing and their influence on engine parameters. Requirements for oil characteristics concern the temperature rise of the boost air and sediment formation on the compressor. Sediments on the compressor heavily influence its efficiency and durability, both raising the temperature of the boost air and lowering the efficiency of the entire engine.
Determination of the influence of the fuel in use on engine parameters, efficiency, exhaust emissions, injection system functionality, etc. Tests of injector nozzle clogging, comparisons of fuels and additives (for engine clean-up or higher performance) and durability tests are performed. Depending on the test type, suitable specialist apparatus is used; for example, a fuel consumption meter together with a fuel conditioning system, exhaust analysers or opacimeters. Engine dynos are equipped with lines supplying the engine with liquid and gaseous fuels. When needed, there is the possibility of combining fuels or additives in order to achieve the desired mixture. Analyses of the chemical composition of fuels, fuel mixtures or sediments formed during the fuel combustion process are performed on site and can greatly improve the analysis of results and the testing process.
Fuel economy tests are conducted to determine the specific fuel consumption of an engine fuelled with various fuel types, using high precision measuring equipment monitoring fuel consumption which is integrated into the fuel conditioning system (maintaining the fuel temperature and pressure).
Comparative tests of the “benchmarking” type are conducted on an engine dyno in order to determine the influence fuel and engine oil produced by different manufacturers on engine parameters. During the test, comparative analyses are conducted based on data such as: engine performance, exhaust emissions, fuel consumption, engine subassembly wear and other defined factors. This type of testing allows evaluation of products available on the market and the selection of fuels or engine oils meeting customer requirements.
These tests aim to determine the influence of using “dirty” fuel on the formation of sediments and injector nozzle clogging/coking, as well as evaluation of the usage of cleanup additives. Modern diesel engines are equipped with injection systems which require fuels of the highest quality. Due to that fact, tests are conducted on an engine dyno with the aim of specifying the influence of elements like sodium and potassium on the propensity for sediment formation in the injectors’ nozzles at high temperatures, which results in a deterioration of spray formation, a decrease in engine performance and an increase in fuel consumption. Simultaneously, tests of cleanup additives – which decrease the formation of sediments and restore the original engine parameters – are conducted.
In this type of oil test, the gearbox works in all gears at two load points, i.e. at maximum torque and at maximum power. Loading the gearbox in this way, it is possible to simulate a high vehicle mileage in a relatively short time (for example, approximately 150000 km for a petrol engine in around 5 weeks, and approximately 180000 km for a Diesel engine in around 6 weeks). Obtaining a daily mileage at a level of 4000 to 5000 km during road testing would be impossible – furthermore, it is worth emphasizing that the reproducibility of the results generated during bench tests is crucial for this type of research.
