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Technical Paper

Impact of Engine Age and Engine Hardware on Low-Speed Pre-Ignition

2018-09-10
2018-01-1663
For engines used in LSPI testing, the life of the engine is often limited as LSPI activity decays with age. This reduction in LSPI activity may correlate to the engine liner wear and it is suggested that the amount of oil transport along the engine liner, which is a function of the liner roughness amongst other factors, is a dominant mechanism for this observed reduction. ...Low-speed pre-ignition (LSPI) is a well-studied phenomenon in boosted, spark ignition engines. The impact of lubricant formulation has received a lot of attention in recent years, yet the impact of engine hardware and engine wear on LSPI is still not fully understood. ...The impact of lubricant formulation has received a lot of attention in recent years, yet the impact of engine hardware and engine wear on LSPI is still not fully understood. This paper addresses some of these questions using results from multiple installations of the GM 2.0 L LHU engine platform.
Technical Paper

On-Road Monitoring of Low Speed Pre-Ignition

2018-09-10
2018-01-1676
The most notable of these is an abnormal combustion phenomenon known as low speed pre-ignition (LSPI). LSPI is an uncontrolled combustion event that takes place prior to spark ignition, often resulting in knock, and has been known to cause catastrophic engine damage. ...Several engine tests have been developed within the industry to better understand the phenomenon of LSPI. While data from these tests have greatly increased the industry’s knowledge about LSPI, they may not accurately represent LSPI as it occurs while the vehicle is in actual service. ...LSPI is an uncontrolled combustion event that takes place prior to spark ignition, often resulting in knock, and has been known to cause catastrophic engine damage. LSPI propensity depends on a number of factors including engine design, calibration, fuel properties and engine oil formulation.
Journal Article

The Impact of Lubricant Volatility, Viscosity and Detergent Chemistry on Low Speed Pre-Ignition Behavior

2017-03-28
2017-01-0685
It was observed that increasing the concentration of calcium leads to an increase in the LSPI rate. At low calcium levels, near-zero LSPI rates were observed. The addition of zinc and molybdenum additives had a negative effect on the LSPI rate; however, this was only seen at higher calcium concentrations. ...Given these results, there is no indication that the general trend towards lower viscosities will prove problematic for LSPI. There is also the potential for improving LSPI rates without reducing detergent concentrations if the observed magnesium result can be confirmed. ...The impact of additive and oil chemistry on low speed pre-ignition (LSPI) was evaluated. An additive metals matrix varied the levels of zinc dialkyldithiophosphate (ZDDP), calcium sulfonate, and molybdenum within the range of commercially available engine lubricants.
Technical Paper

Assessment of the impact of low-speed-pre-ignition mitigation techniques on emission levels

2018-09-03
2018-36-0100
Low-speed-pre-ignition (LSPI) presents a great challenge for developing smaller, more efficient internal combustion engines. ...Current research focuses on understanding the causes of LSPI and developing strategies to mitigate its intensity or eliminate it completely. On this paper, the effect of different LSPI mitigation strategies on emission levels is evaluated. ...On this paper, the effect of different LSPI mitigation strategies on emission levels is evaluated. For this purpose, a 1.0 naturally aspirated port fuel injection (PFI) engine was used.
Journal Article

Influence of Crankcase Oil Properties on Low-Speed Pre-Ignition Encountered in a Highly-Boosted Gasoline Direct Injection Engine

2016-10-17
2016-01-2270
Followings were found: 1) LSPI events were observed when the engine was operated with a stoichiometric mixture for all the oils tested. 2) No clear indication on which SAE oil tested had a stronger influence on LSPI than other oils, either promoting or inhibiting LSPI, because the influences on LSPI of the related oil properties might not be as strong as that of the high gasoline content in the oils, which reached about 6% in the tests. 3) Behavior of LSPI was random in all the tests and a particular LSPI pattern observed in a test was difficult to be reproduced under the same condition. ...Followings were found: 1) LSPI events were observed when the engine was operated with a stoichiometric mixture for all the oils tested. 2) No clear indication on which SAE oil tested had a stronger influence on LSPI than other oils, either promoting or inhibiting LSPI, because the influences on LSPI of the related oil properties might not be as strong as that of the high gasoline content in the oils, which reached about 6% in the tests. 3) Behavior of LSPI was random in all the tests and a particular LSPI pattern observed in a test was difficult to be reproduced under the same condition. ...This paper reports an experimental investigation on the influence of the crankcase oil properties on the engine combustion in the low-speed pre-ignition (LSPI) zone. The investigation was conducted on a highly boosted 1.5L TGDI engine operated at the low-speed-end maximum torque, at which LSPI events were observed most frequently.
Journal Article

Combined Effects of Engine and Oil Age on Low Speed Pre-Ignition

2019-01-15
2019-01-0033
The impact of lubricant formulation has arguably received the most attention, leading to the introduction of the Sequence IX test for LSPI as part of the API SN PLUS lubricant service category. This test, as with most other LSPI evaluations, considers the performance of the fresh oil. ...For each engine, multiple tests, each comprising of multiple segments of a high-load, low-speed test point, known to amplify the occurrence of LSPI, were analyzed to investigate the combined effect of oil and engine age on LSPI activity. Three different baseline oils, which were repeated multiple times, as well as several candidate oils, were included in the data set. ...Selected oils were subject to extended LSPI tests, but no correlations could be found between LSPI activity and used oil analyses results.
Journal Article

Engine Operating Condition and Gasoline Fuel Composition Effects on Low-Speed Pre-Ignition in High-Performance Spark Ignited Gasoline Engines

2011-04-12
2011-01-0342
Hence, a new combustion phenomenon has been observed at high loads and low engine speed and is referred to as Low-Speed Pre-Ignition or LSPI. In cycles with LSPI, the air/fuel mixture is ignited prior to the spark which results in the initial flame propagation quickly transforming into heavy engine knock. ...In the attempt to gain a better understanding of the causes of and potential mitigation methods for LSPI, several engine controls factors and operating conditions were investigated with respect to their effects on LSPI. It was recognized that the two dominant factors in influencing the LSPI occurrence frequency are engine load as governed by fueling rate (energy flux) and in-cylinder air/fuel ratio. ...From this study, it was recognized that the fuel chemical composition strongly influences the likelihood and magnitude of LSPI. Fuel blends with high levels of aromatics increase the frequency at which LSPI occurs somewhat where as oxygenated fuels and, especially, low aromatic blends reduced the LSPI frequency.
Journal Article

Engine Oil Additive Impacts on Low Speed Pre-Ignition

2016-10-17
2016-01-2277
Consistent with previous reports, the detergent system was found to have the largest impact on LSPI frequency. Furthermore, once a balanced detergent system was identified and its LSPI impact was minimized, the effect of other additives, ash-containing as well as ashless, became apparent. ...Low speed pre-ignition (LSPI) is an undesirable combustion phenomenon that limits the fuel economy, drivability, emissions and durability performance of modern turbocharged engines. ...Because of the potential to catastrophically damage an engine after only a single pre-ignition event, the ability to reduce LSPI frequency has grown in importance over the last several years. This is evident in the significant increase in industry publications.
Journal Article

Controlling Low-Speed Pre-Ignition in Modern Automotive Equipment Part 3: Identification of Key Additive Component Types and Other Lubricant Composition Effects on Low-Speed Pre-Ignition

2016-04-05
2016-01-0717
The increased boost pressures are creating a new abnormal combustion phenomenon known as Low-Speed Pre-Ignition (LSPI). Lubricants and fuels have been implicated as significant influencers of LSPI frequency and intensity. ...This paper explores major lubricant components in order to assess their impact on LSPI activity as promoters, quenchers or having no effect (neutral) on LSPI based on this baseline lubricant, with a strong focus on the most common metal detergent cations used in modern automotive lubricants. ...Part 1 of the series described the development of a statistical approach for measuring and quantifying LSPI activity. This statistical approach was shown to be consistent and repeatable. Part 2 of the series further refined the methodology from Part 1 to reduce the frequency of false positives and negatives.
Technical Paper

Understanding degradation of engine oil additives and its effect on abnormal combustion in a gasoline engine

2023-09-29
2023-32-0035
Engine oil additives have been found to affect abnormal combustion in turbocharged gasoline direct injection (TGDI) engines, called low speed pre-ignition (LSPI). Some of metal containing additives such as zinc dithiophosphates (ZnDTP) and molybdenum dithiocarbamates (MoDTC) have been found to reduce LSPI events. ...Some of metal containing additives such as zinc dithiophosphates (ZnDTP) and molybdenum dithiocarbamates (MoDTC) have been found to reduce LSPI events. In this study, we investigated degradation of ZnDTP and MoDTC in gasoline engine operation and effects of the degradation on LSPI performance. ...In this study, we investigated degradation of ZnDTP and MoDTC in gasoline engine operation and effects of the degradation on LSPI performance.
Technical Paper

Alternative Engine Oil Formulating Solutions to Reduce Low Speed Pre-Ignition

2019-12-19
2019-01-2153
Operating downsized, turbocharged, direct injection engines at low speeds and high loads has led to an abnormal combustion phenomenon known as Low Speed Pre-Ignition (LSPI), wherein the fuel-air mixture ignites before the spark occurs. LSPI can lead to extremely high pressures in the combustion chamber, which can damage hardware such as pistons, piston rings, and spark plugs. ...Lubricants, fuels, and engine operating conditions have been shown to impact LSPI. Any of these can be modified to improve LSPI performance. One solution which has been used widely in the industry is reformulating the lubricant additive package. ...In particular, calcium-based detergents have been shown to promote LSPI, while magnesium detergents appear neutral to LSPI. Reducing the usage of calcium detergents can impact other performance areas such as deposit control and fuel economy, and limits formulating flexibility.
Journal Article

The Effects of Piston Crevices and Injection Strategy on Low-Speed Pre-Ignition in Boosted SI Engines

2012-04-16
2012-01-1148
Previous experiments associated increases in hydrocarbon emissions with the blowdown event of an LSPI cycle [1]. Also, the same experiments showed that there was a dependency of the LSPI activity on fuel and/or lubricant compositions [1]. ...Based on these findings it was hypothesized that accumulated hydrocarbons play a role in LSPI and are consumed during LSPI events. A potential source for accumulated HC is the top land piston crevice. ...Further experiments were conducted to determine the sensitivity of the effect of the shape and size of the crevice volume on the LSPI rate, yielding significant changes in the LSPI frequency. In addition to the piston hardware study, it was found that the LSPI behavior is strongly dependent on the mixture formation, particularly the injection strategy and type of injection system used (PFI versus GDI).
Journal Article

The Effect of EGR on Low-Speed Pre-Ignition in Boosted SI Engines

2011-04-12
2011-01-0339
However, in highly boosted SI engines - where the engine displacement is reduced and turbocharging is employed to increase specific power - a new combustion phenomenon, described as Low-Speed Pre-Ignition (LSPI), has been exhibited. LSPI is characterized as a pre-ignition event typically followed by heavy knock, which has the potential to cause degradation of the engine. ...By operating the engine with 10% EGR an increase in fueling rates of 15% and engine torque of 17% was possible while reducing LSPI frequency by roughly 80% and LSPI intensity by approximately 30% over non-EGR conditions. ...However, because LSPI events occur only sporadically and in an uncontrolled fashion, it is difficult to identify the causes for this phenomenon and to develop solutions to suppress it.
Technical Paper

A real-world fleet test of the effects of engine oil on Low Speed Pre-Ignition occurrence in TGDi engine

2019-12-19
2019-01-2294
The findings from this study have shown that LSPI does happen in the field and engine oil formulations impact the number of LSPI events whilst operating in uncontrolled real-world conditions, further confirming that the right engine oil formulation is a critical component for protecting TGDi engines. ...In the last decade, numerous studies have been conducted to investigate the mechanism of Low Speed Pre-Ignition (LSPI) in Turbocharged Gasoline Direct Injection (TGDi) engines. According to technical reports, engine oil formulations can significantly influence the occurrence of LSPI particularly when higher levels of calcium-based additives are used, increasing the tendency for LSPI events to occur. ...According to technical reports, engine oil formulations can significantly influence the occurrence of LSPI particularly when higher levels of calcium-based additives are used, increasing the tendency for LSPI events to occur.
Technical Paper

Autoignition of a Lubricating Oil Droplet with Fuel Ingredients on Abnormal Combustion of Supercharged SI Engine

2020-11-30
2020-32-2318
It is called Low Speed Pre-ignition (LSPI). The lubricating oil which has a tolerance for LSPI has been introduced already in automobile market nowadays. ...However, cause and mechanism of LSPI does not clear sufficiently. It has been reported that the peculiar behavior of LSPI corresponded with behavior of lubricating oil from piston crown [1, 2]. ...This paper focuses on effect of fuel ingredients on autoignition of a lubricating oil droplet about LSPI. On the ignition source point of view, it is important to clear the mechanism of a lubricating oil droplet autoignition in cylinder.
Technical Paper

Investigation of Engine Oil Effect on Abnormal Combustion in Turbocharged Direct Injection - Spark Ignition Engines (Part 2)

2013-10-14
2013-01-2569
Engine test that consisted of 2 phases was designed in order to confirm the correlation between LSPI frequency and engine oil degradation. The LSPI frequency measurement phase and engine oil degradation operation phase were conducted alternatively without changing engine oil. ...Abnormal combustion phenomena referred to as Low Speed Pre-Ignition (LSPI) has been recognized as potential restriction to improve low speed engine torque that contributes fuel economy improvement. ...As reported in the part 1 [1], the study showed that engine oil composition had significant influence on the frequency of LSPI in both preventive and contributory effects. Further investigation was conducted to evaluate engine oil formulation variables and other factors that may have influences on the LSPI, such as engine oil degradation.
Technical Paper

Effect of Oil Additives and Fuel Concentration in Lubricating Oil on Abnormal Combustion of Supercharged SI Engine

2022-01-09
2022-32-0007
The spark ignition engine with supercharger which is supplied the fuel directly in cylinder (SI engine) has a phenomenon of abnormal combustion as called Low Speed Pre-Ignition (LSPI). It has been reported that the LSPI would be related with lubricating oil and the ingredients of fuel and oil additives [1] [2]. ...The mechanism of LSPI does not clear sufficiently, especially, relation ignition source of LSPI with the lubricating oil additives and the fuel concentration in lubricating oil. ...This research focuses on the source of LSPI which is autoignition of a lubricating oil droplet in cylinder. The effect of oil additives as Zn, Mo, Mg, Ca and concentration of fuel on autoignition of a lubricating oil droplet has been investigated.
Technical Paper

Controlling Low-Speed Pre-Ignition in Modern Automotive Equipment: Defining Approaches to and Methods for Analyzing Data in New Studies of Lubricant and Fuel-Related Effects (Part 2)

2016-04-05
2016-01-0716
The type and quality of the fuel and lubricant has been found to influence LSPI occurrence rates. A methodology for studying LSPI has been implemented, and a rigorous statistical approach for studying the data from a stationary engine test can provide consistent results as shown in Part 1 of the series. ...In recent years, an abnormal combustion phenomenon called low-speed pre-ignition (LSPI) has arisen from the downsizing of gasoline engines in order to improve fuel economy and comply with global CO2 legislation. ...A methodology for studying LSPI has been implemented, and a rigorous statistical approach for studying the data from a stationary engine test can provide consistent results as shown in Part 1 of the series. LSPI events can be determined by an iterative statistical procedure based on calculating the mean and standard deviation of peak pressure (PP) and crank angle location of 2% mass fraction burned (MFB02) data, determining cycles with parameters which exceeded n standard deviations from the mean and identifying outliers.
Technical Paper

Lubricating Oil Droplets from Piston Crown on Abnormal Combustion in Supercharged SI Engine

2020-11-30
2020-32-2302
However, it has a problem of abnormal combustion which is called Low Speed Pre-ignition (LSPI). It is cleared gradually that the character of lubricating oil effects on LSPI. The lubricating oil which has a tolerance for LSPI has been introduced already in the market nowadays. ...The lubricating oil which has a tolerance for LSPI has been introduced already in the market nowadays. However, cause and mechanism of LSPI occurrence does not clear sufficiently. ...In previous conference SETC 2018, it was reported that the peculiar behavior of LSPI corresponded with behavior of lubricating oil from piston crown [1, 2, 3]. This paper focuses on frequency of lubricating oil scattering from piston crown.
Journal Article

Market Fuel Effects on Low Speed Pre-Ignition

2021-04-06
2021-01-0487
Conclusions about the effects of fuel on LSPI have been more varied, but as part of a recently completed research consortium, the LSPI tendency of market fuels with a range of properties, including composition, boiling point distribution, ethanol content and particulate matter index (PMI) were evaluated. ...It was found that the PMI and certain boiling points correlated the best with the frequency of LSPI events. In addition, decreased LSPI severity, quantified by the peak-to-peak knock values, was found to correspond with increased octane numbers and higher ethanol content of the market fuels. ...Low-Speed Pre-ignition (LSPI) is an undesirable abnormal combustion phenomenon observed in turbocharged, direct-injection spark-ignition engines and is characterized by early heat release, high cylinder pressures and severe, potentially damaging knock.
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