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Articles on Engine Knock

Started by SHOdded, April 05, 2016, 08:29:17 AM

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SHOdded

2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

Detonation (aka Knock) – Destroyer of Engines and Bank Accounts
http://www.vikingspeedshop.com/detonation/
2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

#2
Ford: Ticking/Knocking Noise Or Rattle From Engine On Startup
http://www.underhoodservice.com/ford-tickingknocking-noise-rattle-engine-startup/

QuoteSome vehicles equipped with a 4.6L, 3-valve or 5.4L, 3-valve engine may exhibit a ticking and/or knocking noise after reaching normal operating temperature, or may exhibit a rattle upon starting. The noise may also be described as ticks, taps, knocks or thumps. In some cases the noise may be a normal characteristic of these engines. In other cases the noise may require further investigation. Sorting out and defining the noise as reported by the customer is important to diagnose and repair the condition.

Models:

2005 Mustang
2004 F-150
2005 F-150, F-250, F-350
2005 Expedition
2005 Lincoln Navigator

Note: The 4.6L, 3-valve and the 5.4L, 3-valve engines are installed in several vehicle platforms, which may influence the intensity of noise due to vehicle differences in sound transmission paths, hood and body insulation packages and root cause of the component(s) causing the noise.

Pre-checks

1. Make sure you have a detailed description of the noise the customer is concerned with, including details such as:
• Is the noise occurring at idle or above idle speed?
• Does it disappear above 1,200 RPM?
• Does the noise occur when the engine is hot? Cold? Both?

These engines generate a lot of "normal" noises, so it is critical to confirm the noise the customer is concerned with and the environment the customer is in when the noise is noticeable to them. Validate by using your own perception.

2. Compare the noise generated with a new vehicle, if available, with an engine build date of March 30, 2005, or later for the Mustang and April 18, 2005, or later for the F-150, F-250, F-350, Expedition and Navigator.
3. Diagnose the noise when the engine is at normal operating temperature (oil at 160º F or above). Verify the oil temperature with a diagnostic scan tool and monitor the engine oil temperature (EOT) PID. Startup rattle may only occur with cold oil.
4. Check the type of oil filter installed on the vehicle. A dirty or clogged filter may cause a pressure drop. Look for aftermarket brands not recognized in the market or a production filter that has gone beyond the standard Ford-recommended change interval.
5. Check for signs of oil brand used and viscosity.

Once the above pre-checks are complete, check for sound level from the following components in the order listed. Compare the sound from these components to the noise the customer is concerned with to determine the source.

Injection/Fuel System

Injector noise (ticking) is considered normal. Noise increases with RPM, hot or cold, and is recognized at the top of the engine.

Valve Train

Lash adjusters can make a ticking or tapping noise noticeable at any engine RPM or temperature. The noise is audible through the wheel well or an open hood. However, with the hood down, the lash adjuster noise can be heard as a light tapping noise through the wheel well and is considered normal.

Tracing this noise requires isolating it to a cylinder bank. If one bank is louder than the other bank, focus the diagnosis on the loud bank. If both banks seem loud with the hood down, compare wheel well sound level to another comparable vehicle.

Use a stethoscope on the top of the cam cover bolt heads to confirm which bank is affected. Move the probe from front to rear if necessary.

If isolated, only replace the intake and exhaust lifters on the affected cylinder bank.

Variable Cam Timing

The 4.6L, 3-valve and 5.4L, 3-valve variable cam timing (VCT) feature may emit a light knock in normal operation and is audible only at idle speed with a hot engine (gear selector in park or neutral). However, it may be masked by or mistaken for other noises generated from either the injector firing or a malfunctioning valve train as described earlier.

The noise does not affect the performance or durability of the part.

VCT phasers may knock at hot idle. The knock may be heard inside the passenger compartment or the wheel well area. Some light noise is normal. The engine may require a cold soak overnight to effectively make a full diagnosis at hot idle, particularly when a VCT phaser is suspected. The knock is not prevalent at cold temperatures.

To Test For VCT Noise

1. Place the transmission in park or neutral
2. Bring engine oil temperature to 160º F or above as indicated by the scan tool EOT PID.
3. Allow engine to idle and determine if noise is noticeable.
4. Set engine speed to over 1,200 RPM. If the noise is a VCT knock, it should disappear.
5. Return the engine speed to idle and verify if the knock returns.

If the noise intensity is more than a lightly audible knock at hot idle than under 1,200 RPM at engine operating temperature, replace the cam phaser using the "In-Vehicle Repair Camshaft Phaser and Sprocket" procedure found in the Workshop Manual, section 303-01.

Startup Rattle

Some 2004 F-150 and 2005 F-150, Expedition, Navigator, F-Super Duty and Mustang vehicles may have a rattle on startup that lasts 1 to 3 seconds. If initial pre-checks have been completed and the noise sounds like it is coming from the front engine, replace the VCT Phaser Kit. If the engine continues to make the rattle noise after initial startup, do not exchange the VCT.

Courtesy of Identifix.
2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

#5
Engine oil, LSPI, and super knock
http://www.amsoil.com/newsstand/articles/prevent-super-knock/
Quote
New Oil Technology Needed to Prevent Super Knock
A potentially catastrophic problem is surfacing in today's engines. Here's how we're working to solve it.

New Oil Technology Needed to Prevent Super Knock
Original equipment manufacturers (OEMs) have been aggressively downsizing engines to meet strict fuel-economy and emissions standards without sacrificing power and torque. Most new engines today use some combination of turbochargers, direct-fuel injection and variable valve timing to make more power than their larger counterparts while delivering improved fuel economy.

This scenario seems like all up-side for drivers. But today's smaller, hotter-running engines pose significant challenges to lubricants. The latest is a phenomenon called low-speed pre-ignition (LSPI), which can destroy pistons and connecting rods.



What is LSPI?

As its name implies, LSPI is the spontaneous ignition of the fuel/air mixture prior to spark-triggered ignition. It's another version of pre-ignition, which has been around since engines were invented. In this case, though, it occurs under low-speed, high-torque conditions in turbocharged gasoline-direct-injected (TGDI) engines and is much more destructive than typical pre-ignition.

In a properly operating engine, spark-triggered ignition typically occurs a few degrees before the piston reaches top dead center (TDC). This careful timing ensures the downward force of the exploding fuel/air mixture works in tandem with downward piston momentum, resulting in optimum engine efficiency and power.

LSPI effectively throws off engine timing. In turbocharged engines operating under certain conditions, particularly at low speeds and under high torque, like when taking off from a stoplight, the fuel/air can spontaneously ignite too early in the combustion cycle. The expanding combustion charge collides with the piston as it's still moving up the cylinder. The collision between the exploding combustion charge and the upward-moving piston can destroy the pistons or connecting rods.

LSPI

What causes LSPI?

Current thinking suggests the cause is due in part to oil/fuel droplets or particles in the cylinder auto-igniting randomly. The droplets/particles heat enough to ignite the air/fuel mixture before the spark plug ignites. This means oil formulation can play a role in reducing LSPI.

Testing has shown that certain motor oil components can promote LSPI, while others can help quench it. Even the formulation of gasoline plays a role; however, it's easier to solve the problem by reformulating motor oil.

Oil formulators face a difficult balancing act. It's no easy task figuring out how to formulate a motor oil that delivers excellent wear protection, resists the increased heat of turbocharged engines, prevents deposits, acts as a hydraulic fluid and, now, combats LSPI. The important thing to keep in mind is that it is the performance of the total formulation that counts, not just the quantity of one or two motor oil components.

New performance specs coming

Difficult or not, fighting LSPI must be done. Next-generation oils will need to pass an LSPI test to meet the new API SP and ILSAC GF-6 performance specifications set to take effect in mid-2019. General Motors is ahead of the game and requires oils to pass their own LSPI test to meet its updated GM dexos1 specification (known as dexos1:2015) scheduled to take effect Aug. 31, 2017.

For now, you don't have to worry too much. Your vehicle's computer is programmed to avoid operating conditions that lead to LSPI. However, operating your engine under those conditions does promise fuel economy gains, so once oils hit the market that combat LSPI, you can bet the OEMs will program their vehicles to benefit from those efficiency gains.

We're hard at work reformulating Signature Series Synthetic Motor Oil, XL Synthetic Motor Oil and OE Synthetic Motor Oil in preparation for the new engine challenges addressed by the new specifications.

After months of vigorous testing, the results are in: AMSOIL synthetic motor oil provided 100 percent protection against LSPI in the engine test required for the GM dexos1  Gen 2 specification, proving it can protect turbocharged direct-injected engines.

The complete line of AMSOIL synthetic motor oils will be upgraded to meet these challenges. Stay tuned.
2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

https://www.motor.com/magazine-summary/resolving-low-speed-pre-ignition/

QuoteJANUARY 2017 ISSUE
RESOLVING LOW-SPEED PRE-IGNITION
By Bob Chabot

Unless resolved, LSPI is a barrier to achieving aggressive fuel economy and emissions standards.

Market demand and legislation are driving automakers to find ways to improve fuel economy and reduce CO2 emissions across their vehicle fleets. U.S. regulations will see passenger car fuel economy standards jump from an average of 35.5 mpg in 2016 to 54.5 in 2025, while ever-lowering tolerances for greenhouse gas emissions. Even more aggressive standards have been proposed in Europe and Asia.

To achieve the goals of more power, torque and pressure, automakers initially focused on downsizing gasoline engines. For example, Ford Motor Co. and General Motors Corp. have launched 3-cylinder, 1.0L boosted engines (EcoBoost and Ecotec, respectively) that deliver the same output as their 1.6L 4-cylinder engines, but also provide an approximately 20% improvement in fuel economy and lower CO2 emissions. These reduced engine displacements delivered improved engine efficiencies that included lower pumping mechanical friction losses, down-speeding of the engine by using higher transmission gear ratios, higher engine torque at lower engine speeds; and lower gases-to-wall heat transfer.

Both Ford and GM say they have plans to increase production of these smaller engines to meet growing consumer demand in markets worldwide. Ford already produces 100,000 EcoBoost engines per month, and aims to offer the technology in approximately 80% of its vehicles by 2016. GM says it expects to produce 2.5 million units annually at five global plants by 2017.

But early downsized engines also sacrificed engine performance. To offset lower power output, automakers began adding turbochargers to boost engine operating pressure. In addition, the rapid proliferation of turbocharged, higher pressure gasoline direct injection (TGDI) engine technology in the past five years has been stunning.


What exactly is low speed pre-ignition (LSPI)? LSPI is an unexpected consequence of downsizing and boosting engines. Also known as stochastic pre-ignition (SPI), megaknock, superknock or deto-knock. LSPI most commonly occurs at low speeds during a period of rapid acceleration. LSPI is believed to be caused by droplets or particles in the combustion chamber—combinations of fuel and oil—that ignite prior to spark, resulting in uncontrolled, abnormal combustion. This creates spikes in engine pressure, ultimately causing internal engine damage. In some cases, researchers reported that just a single LSPI event was sufficient to cause severe engine damage.

In the early days of downsizing and boosting engines, it was not clear how much impact LSPI would have. It soon became apparent that LSPI events were more widespread and that lubricant, fuel and engine design research was needed to determine an optimal path forward. The first step required industry consortia to develop more general knowledge about LSPI.

Initially it was thought that pre-ignition sources were located at hot spots in the cylinder, or were from soot accumulation. However, further optical investigation revealed that pre-ignition actually occurred randomly throughout the combustion chamber, which means surface ignition is not the only source of LSPI.

More current research suggests that the auto-ignition of oil droplets or deposit particles is probably the major cause of LSPI. In addition, it soon became apparent that LSPI events are more widespread than previously thought and that they represent a barrier to automakers safely maximizing performance and fuel efficiency simultaneously, let alone meeting more stringent regulatory standards.

Low-speed pre-ignition is poised to become an increasing service/repair problem. Just five years from now, it's estimated that a quarter of all cars on the road in North America and 39% of global production will utilize this combination of engine hardware. However, despite the benefits of downsized, boosted gasoline engines that operate at low speeds and high torque, an unintended but serious consequence has emerged that the industry must resolve—LSPI.

The challenge in a nutshell? As a larger percentage of today's engines are downsized and turbocharged over time, more vehicles in operation will suffer low-speed pre-ignition and potentially experience engine damage and/or failure. In addition, as more stringent fuel economy standards take effect, vehicles will increasingly be operating in regimes where LSPI events are more likely to occur.

Addressing LSPI sooner than later is top of mind for manufacturers. At the most recent JSAE/SAE Powertrains, Fuels and Lubricants International Meeting held in September 2015 in Kyoto, Japan, LSPI was one of the primary agenda topics. Attendees recognized that advanced downsized and boosted engines now spend much more time in a low-speed high-torque regime that easily leads to LSPI.



At the meeting, industry experts reached consensus on several points:

•LSPI arises from interactions between lubricants, fuels and engine design/operation. Resolving LSPI will likely require a holistic approach that addresses all three areas.

•LSPI occurs very close to the engine's optimum operating area where fuel economy, performance and driveability are balanced under constant load (e.g., highway cruising).

•Downsized, boosted engines can easily slip into LSPI in that zone, which can cause potential engine damage (e.g., broken pistons, bent connecting rods or severe engine failure).

•Until LSPI is rectified, automakers may be restricted in their ability to maximize the performance and fuel efficiency of their advanced engine designs, creating a barrier to meet future demanding fuel-performance and emissions requirements.

No Simple Fix

"LSPI is not a simple problem," explained Thomas Briggs, Jr., manager of engine systems research and development at Southwest Research Institute (SWRI) in San Antonio, TX. Briggs led SWRI's Pre-ignition Prevention Program team that includes industry partners (GM, Ford, Honda, Infineum International, Afton Chemical and others) that began investigating LSPI in 2011.

"When the fuel is injected directly into the combustion chamber, it dilutes the oil film lining the cylinder," Briggs shared. "This fuel dilution reduces the surface tension and viscosity of the oil, causing an oil-fuel mixture to accumulate in the upper reaches of the piston top land crevice. The mechanical energy of the upstroke during compression pushes droplets into the combustion chamber, where they vaporize and can auto-ignite prior to spark ignition and subsequent engine damage.

"The team used high-speed video, crevice sampling and other specialized tools to better determine the source of the problem. Captured video showed that droplets of material were coming out of the piston crevice in the engine. Sometimes those droplets burned, leading to LSPI and strong engine knock. The video also showed that the material was a complex cocktail of fluids—fuel, lubricant, soot and other material. It's clear to us now that resolving LSPI issues will require addressing lubricants, fuels, engine design and more."

Southwest Research Institute and its partners are now involved in a follow-up consortium which started in 2014 and is scheduled to wrap up in 2018. Currently, ways are being investigated to replicate what happens in an engine on a test bench and develop standardized tests for LSPI. This will give researchers greater access and more tools to understand what's going on. The goal is to determine the chemical steps that lead to LSPI, which will help in figuring out what should be done to address it.

The program wrapped up in 2014, having produced information that gave additive companies a rough idea of what was needed to solve the problem. "We already know that LSPI arises when engines are in the 1500-2000 rpm range, a relatively slow speed, while still exerting plenty of torque," Briggs said. "That's also when a large supply of fuel is present. Yesterday's engines spent little time in these operating conditions, but it's very possible they too would experience LSPI if they had."

A Holistic Systems Approach

Industry researchers and manufacturers increasingly realize that vehicles are complex systems that require a holistic approach to resolving problems. Certainly an advance in one area may help, but doing so without considering other areas has already led to unintended consequences. The serious issues caused by LSPI, after downsizing then boosting engines, have amply demonstrated that.

"An area that SWRI is working on now is LSPI testing," Briggs shared. "While LSPI tests already exist that can readily discriminate between the LSPI impact of various lubricant formulations, they are being further refined into upcoming ILSAC GF-6 and GM dexos 1. But we also need to standardize testing across the industry and incorporate new understanding on a dynamic basis into LSPI testing so it remains relevant over time. For instance, continued research on the mechanisms behind LSPI and possible fixes for it in areas outside of lubricant formulation need to be considered as LSPI testing evolves."

"We know LSPI occurs in the combustion chamber, and the most practical solution is a holistic solution that takes into account engine design, engine oil formulation and fuel quality," advised Ian Bell, Research and Development Director for Afton Chemical in Richmond, VA, a company in the lubricant formulation and lubricant manufacturing business. For any manufacturer in one of those areas, solutions must integrate a multiperspective approach. In addition, positive innovation in one area must not severely compromise overall system performance. Whether engine design, lubricant formulation, fuel quality or backwards compatibility, R&D in one area must also include consideration of the others."

For example, Bell noted that when Afton recently presented a survey of LSPI performance for a broad range of commercially available GF-5 lubricant products, all failed proposed LSPI requirements for the new GF-6 standard about to be introduced.

"Lubricant formulations will have to change," Bell said. "But the lubricant manufacturers' holistic solution will need to reduce or eliminate LSPI while still providing improved performance in other areas it hasn't been concerned with before."

Specifically, Bell cited:

Engine Durability. To preserve the chief function of engine oil, a formulation must be able to cool, lubricate and clean engines to reduce wear and maximize service life.

Oil Formulation. Oil additives, such as viscosity modifiers, ensure that oil performs in both hot and cold weather, while performance additives ensure oil remains clean, durable and effective. There is a clear impact from all organic materials, and base oils can also be significant, so lubricant manufacturers must bear this in mind going forward.

Fuel Quality. Today more than ever, oils depend on friction modifiers in fuels to help maximize the amount of usable energy, while maintaining stable viscosity to reduce engine drag.

Backwards Compatibility. The average age of a light vehicle in the U.S. is more than 11 years old, and it's growing. Tomorrow's lubricants must address LSPI in the vehicles of today, yet remain fully compatible and effective in the vehicles of yesterday. The new ILSAC GF-6 and next-generation GM dexos 1 (2015) standards do that.

Lubricant formulation is just one of the elements to resolve the LSPI challenge. Manufacturers in other areas must take a similar approach and collaborate with each other. It's about raising the competency bar across the industry landscape for us all—from those who build vehicles to those who service them.
2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

#7
Effects of fuels and lubricants on low-speed pre-ignition in gasoline engines

https://futurepowertrains.co.uk/wp-content/uploads/2016/01/Future_Powertrain_Conf_2016_BP_dist.pdf

QuoteConclusions
• Stringent vehicle CO2 and fuel economy targets are in place in most major automotive markets.
• Gasoline engine downsizing has been a widely deployed technology in pursuit of these targets.
• The operating conditions in a modern downsized gasoline engines can induce a low-speed pre-ignition problem which can lead to destructive mega-knock events.
• LSPI is influenced by the engine operating conditions and calibration approach, the fuel distillation characteristic, and the chemical composition of the lubricant.
• In particular, for the lubricant, replacing calcium-based detergents with magnesium-based detergents is one possible approach to eliminating LSPI frequency.
• ZDDP appears to have suppressant effect on LSPI.
2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

#8
Influence of the Engine Oil on Pre-ignitions at Highly Supercharged Direct injection Gasoline Engines

https://www.atz-magazine.com/download/2016_77_06%20I_036-041_W%20Vorentflammung%20TU_Wien_101048_online.pdf

QuoteCONCLUSION
The developed test methodology allows very precise reproducible evaluation of oil induced pre-ignitions. The investigations confirm that the oil composition has a significant impact on the pre-ignition behaviour of highly charged gasoline engines. In addition to the base oil properties especially metal-based additives are decisively involved in triggering pre-ignitions. Increasing the calcium content results in a highly non-linear increase in pre-ignition frequency, while magnesium detergents show no tendency to pre-ignite. In addition, antioxidants effectively reduce the tendency to selfignition by reactions in the low temperature regime. With appropriate formulations engine oils will be able to make a significant contribution to reducing the pre-ignition problem.
2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

Chemistry is a complex thing, as this patent shows.  It is not just calcium, but the chemistry of the calcium complex that matters in determining LSPI event occurrence.

https://patents.google.com/patent/US20170015926A1/en



Quote[0207]
As shown in Table 4, there is a significant improvement in LSPI performance when the amount of calcium from an overbased ("OB") detergent is decreased from about 2400 to about 1600 ppm calcium. Comparing R-1 to C-1, the LSPI Ratio was reduced by about 78% but performance in TEOST-33 test went from passing to failing as calcium was decreased. If the amount of calcium from an OB detergent is further reduced to 1100 ppm (C-2), the LSPI Ratio is even more significantly improved; however, performance in the TEOST-33 test is still poor at this level of calcium. In C-3, the detergent system is completely removed demonstrating that without detergent, LSPI is improved 100%. However, again, the TEOST 33 test performance is sacrificed. Example 1-5 utilizes a low based sodium sulfonate instead of the low based calcium sulfonate used in inventive examples I-1, I-2, I-3, and I-4 and shows that a significant reduction in LSPI Ratio can be obtained using a sodium-containing low-based/neutral detergent instead of a calcium-containing low-based/neutral detergent.
[0208]
An unexpected improvement in LSPI can be obtained by combining a low base or neutral ("LB/N") calcium detergent (I-1 to I-4) with an OB calcium detergent without sacrificing performance in the TEOST-33 bench oxidation test. Inventive Example I-1 passes the TEOST-33 test while delivering a more significant improvement in LSPI events with an almost 81% reduction in the LSPI Ratio relative to R-1. Inventive Examples I-2 and I-3 provide an even greater reduction in the LSPI Ratio without loss of performance in the TEOST-33 test. Example I-4 demonstrates the use of a LB/N calcium phenate in place of the LB/N calcium sulfonate. I-4 also shows a significant improvement in the LSPI Ratio as well as passing TEOST 33 test. The examples presented in Table 4 clearly demonstrate that the amount of calcium from an OB calcium detergent may be maintained at a higher level by adding additional calcium from a LB/N calcium detergent while still passing the TEOST 33 test and ensuring a significant reduction in LSPI Ratio. Further, unexpectedly, the results obtained in the TEOST 33 test may be improved even in the absence of high amounts of OB calcium detergent. In fact, off-setting the OB calcium detergent with LB/N calcium detergent, unexpectedly and surprisingly improved TEOST 33 test while also reducing the LSPI Ratio.
[0209]
The present data shows that off-setting OB Ca sulfonate with LB/N Ca sulfonate in an amount of greater than 8% LB/N Ca Sulfonate in the total detergent provides an improvement in LSPI while maintaining performance in TEOST 33 test.
2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

The same team's application for patent on Magnesium-based detergent research

http://www.freepatentsonline.com/y2017/0015927.html

The challenge then becomes keeping that TBN up, as you see in Table 5.  Which probably means shorter OCIs are better, in order to maintain LSPI resistance.

2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

You want to prevent LSPI, but if it happens, you want your engine to be damage-resistant, right?  One way is to improve the coatings applied to piston rings, as stated in this PR blurb from Mahle

QuoteNew MAHLE piston ring coating for high-output engines
Sep 15, 2015, 10:32 ET from MAHLE

FARMINGTON HILLS, Mich., Sept. 15, 2015 /PRNewswire/ -- MAHLE delivers improved top piston rings using a new thermal spray coating for modern high-output direct-injection turbocharged gasoline engines (GTDI).

Under development since 2011 at MAHLE's thermal spray development labs in Muskegon and St. Johns, Michigan, the new process initially was designed for high-output GTDI engines currently in production by two U.S. domestic automakers.

The market for high-output turbocharged engines is expected to achieve a market share of 30 percent or more by 2020.

The new coating also was developed to help meet requirements for new production engines planned for 2018-2020, which call for less cylinder-bore friction and the use of lower-viscosity oils and alternative fuels. It provides the superior performance of a more costly premium inlaid top ring.

The new coating, also referred to as MSC312, improves upon the scuff-and-wear capabilities of MAHLE'S well-known MSC385 coating because of its chromium nitride composition. MSC312 uses chromium nitride in top ring coatings applied through a high-velocity oxygen fuel (HVOF) method.

Typically high-output engines under 3.5 liters are susceptible to low-speed pre-ignition or "mega-knock."

HVOF coatings are the only family of coatings that currently can survive high levels of low-speed pre-ignition in GTDI engines without damaging the top piston ring.

Tested against the MSC385 (chrome carbide HVOF) currently used in several North American production engines, MSC312 improves wear by up to 25 percent as well as providing improved scuff resistance. The thickness of the new coating also can be adjusted to meet engine durability requirements.

Chromium nitride (CrN) coatings are common in the piston-ring industry when applied by physical vapor deposition. CrN generically provides excellent wear resistance and low friction between piston ring and cylinder wall. It also resists scuffing at the ring-to-wall interface. MAHLE's new coating is the first thermally applied piston ring coating to use chromium nitride in its formulation. The addition of molybdenum-chrome provides enhancements to pure CrN.

In the past, top-ring coatings were applied using conventional plasma methods. In downsized GTDI engines conventional top-ring plasma rings are not sufficiently robust to survive high levels of low speed pre-ignition activity associated with low-speed, high-boost conditions found with GTDI engines.

Conventional plasma methods are used for ring production at MAHLE's St. Johns plant and at MAHLE's facilities in Europe, South America and Aguascalientes, Mexico.

About MAHLE:

MAHLE is a leading international supplier to the automotive industry. With its products for combustion engines and their peripherals as well as solutions for electric vehicles, the group addresses all the crucial issues related to the powertrain and air conditioning technology—from engine systems and components to filtration to thermal management. MAHLE products are fitted in every second vehicle worldwide. MAHLE components and systems are also used off the road—in stationary applications, for mobile machinery, as well in railroad, marine, and aerospace applications.

In 2014, the group generated sales of EUR 9.94 billion with around 66,000 employees. Today, MAHLE is represented in over 30 countries with 170 production locations. At 16 major development locations in Germany, Great Britain, Luxembourg, Slovenia, the USA, Brazil, Japan, China, and India, more than 5,000 development engineers and technicians are working on innovative solutions.

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2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

Hmm ... base oil and LSPI?  Idea still in development

Lube oil chemistry influences on autoignition as measured in an Ignition Quality Tester
works.bepress.com/francis-haas/7/download

QuoteSeparate variation in Ca and Mg additive package levels, indicated no statistically significant
ignition effect. Similarly, neither aging of the oils nor peroxide addition yielded a significant effect
on measured DCNs (Derived Cetane Numbers) of oil-surrogate blends. Considering that some of these tests also screened for
binary and ternary synergies among compositional factors, many of the present results indicate a
general insensitivity of homogeneous ignition to oil/additive formulations for the base oil currently
investigated. However, DCN-indicated ignition does significantly respond to base oil organic
composition characteristics classified by API Group number. The measured DCNs range from
19.6 to 42.1 and monotonically increase as Group number increases from I→IV. Notably, one
Group V oil reduced DCN at the 25% blend level. The present screening results indicate that, at
ASTM D6890 DCN test conditions, the bulk hydrocarbon chemistry governs ignition and renders
secondary any effects of reasonable levels of Ca and Mg detergent, oil degradation by aging, or
absorption of metastable combustion byproducts.
2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

https://www.thefreelibrary.com/Influence+of+crankcase+oil+properties+on+low-speed+pre-ignition...-a0478973890

Quote
Influence of crankcase oil properties on low-speed pre-ignition encountered in a highly-boosted gasoline direct injection engine.

Author:   Teng, Ho; Luo, Xuwei; Hu, Tingjun; Miao, Ruigang; Wu, Min; Chen, Bin; Zeng, Fanhua
Article Type:   Report
Date:   Nov 1, 2016
Words:   5910
Publication:   SAE International Journal of Fuels and Lubricants
ISSN:   1946-3952
INTRODUCTION

[FIGURE 1 OMITTED]

For turbo-charged gasoline direction injection (TGDI) engines with homogeneous mixture combustion, pre-ignition (PI) is frequently encountered, typically at speeds < 2500 rpm and brake mean effective pressures (BMEP) [greater than or equal to] 15 bar. This abnormal combustion is known as low-speed pre-ignition (LSPI). Since PI occurs much earlier than the spark timing for normal combustions, it often leads to severe knock combustion. This abnormal combustion may be characterized with three stages: early-stage combustion triggered by PI, rapid combustion, and severe knock combustion with huge pressure fluctuations as shown in Figure 1. Since the pressure fluctuations during the knock combustion are on the same order of magnitude for the peak firing pressures (PFP) in normal combustions, the PI induced abnormal combustion is also termed as the super knock.

[FIGURE 2 OMITTED]

The cause for LSPI is widely believed to be due to the liquid particles of the crankcase oil entering the engine cylinder [1, 2, 3, 4, 5, 6, 7, 8, 9]. For TGDI engines, the oil enters the cylinder mainly in two ways: as the oil transport through the piston-liner clearance and as the oil loading in the blowby recirculation or the oil carryover. Figure 2 illustrates the oil transport mechanism proposed by Yilmaz [10]: the oil entering the engine cylinder through the piston-liner clearance in three ways, i.e., oil throw-off by the piston motion, the oil mist in the reverse gas flow when the cylinder pressure becomes lower than that in the ring grooves, and evaporation of the oil wetted the cylinder wall. The oil throw off and the oil mist in the reverse gas are related to the piston motion and thus may be combined as the oil transport. According to the test results of Yilmaz, the oil transport increases with the engine speed; at a given engine speed, the oil transport decreases with the engine load as a result of increase in oil evaporation from the cylinder wall [10]. This suggests that the oil transport may not be a unique characteristic for the low-speed and high-load operations where LSPI is encountered.

[FIGURE 3 OMITTED]

For highly boosted TGDI engines, the blowby recirculation reaches its maximum in the LSPI zone on the engine speed-load map [11]. Due to a high level of fuel dilution of the crankcase oil in the LSPI zone [12], the crankcase oil becomes highly volatile and, as a result, considerable liquid oil particles are carried by the blowby recirculation and burned in the engine cylinder as part of the oil consumption. After being cooled at the intercooler, small liquid oil particles may coalesce and form large and more viscous liquid oil particles. Figure 3 shows a phenomenon of hydrocarbon fouling or carbon deposits on the back and stem of the intake valves due to the liquid oil particles in the blowby recirculation for a 1.5L TGDI engine tested by the present authors. Considerable carbon deposits were built up on the backs and stems of the intake valves after the engine was operated at low speeds and high loads for a certain period of time. As the liquid oil particles landed on the intake valves and intake ports, some large and viscous liquid oil particles in the blowby recirculation could also land on the combustion chamber roof during scavenging, which is used as a method for boosting the low speed torques in almost all TGDI engines for [11,12]. Based on the blowby flow rates in the scavenging zone and the characteristics of the liquid oil particles in the blowby recirculation, the number of liquid oil particles entering the engine cylinder as the oil carryover is estimated on orders of [10.sup.7]~[10.sup.8]/cycle for each cylinder [11]. Due to the cooling in the intercooler, the liquid oil particles entering the engine cylinder become less volatile and thus more easily land on the combustion chamber roof with an assist of the air short circuiting flow from the intake ports to the exhaust ports during scavenging. If they are not fully vaporized in the compression stroke, then these liquid oil particles could become the triggers for LSPI.

The influence of the additives in the oil has been studied by many investigators [e.g., 13, 14, 15, 16, 17, 18, 19, 20]. Most of these investigations were focused on the oil-soluble metals added into the oil as the detergents. According to these studies, the impacts on LSPI of the oil additives can be classified as promoters, quenchers, or neutral (no effect). Based on our tests on three different highly boosted TGDI engines (1.5L/1.8L/2.0L) all lubricated with 5W-30 synthetic oil, LSPI is seldom encountered in a new engine with fresh oil, but it is unavoidable for the engines operated for a long period of time, especially with the contaminated crankcase oil and the contaminated intake system. This indicates that the engine condition and the levels of the oil as well as the intake system contaminations have a significant impact on LSPI. In a previous SAE paper [12], we investigated the effect on LSPI of the fuel dilution of the crankcase oil. The aim of this investigation is to understand the influence on LSPI of the crankcase oil with different SAE viscosity grades. Six different market available engine oils were tested with the same engine at the same load point. The oils tested covering SAE 0W-20, 0W-30, 0W-40, 5W-20, 5W-30 and 5W-40 from two different international oil suppliers.

TGDI ENGINE UNDER STUDY

The engine under study is an inline 4-cylinder 1.5L TGDI engine fueled with RON93 gasoline. The basic engine parameters are presented in Table 1. The engine is equipped with a high-efficiency, waste-gated turbo charger and dual cam-phasers allowing both intake and exhaust cams to shift up to 60 deg-CA with respect to their home positions independently. The engine is highly boosted and has a flat torque curve with low-end speed at 1500 rpm and high-end speed at 4600 rpm. Figure 4 shows the engine torque and power curves normalized with their peak values. The side-mounted fuel injector has 6 orifices, with the maximum injection pressure being 150 bar. The fuel spray targets on the piston top are illustrated in Figure 5.

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

The base engine oil is SAE 5W-30 synthetic oil with high temperature and high shear performance. Selected physical properties given in the oil specification are presented in Table 2. Figure 6 shows the distillation curve for the RON93 gasoline used in the engine tests. The oil temperature range for the engine operations is shown in the shaded area for a reference. It is seen that for oil temperatures greater than 140[degrees]C, up to 25% of the gasoline entering the oil may remain in the oil in case of fuel dilution, which is unavoidable in TGDI engines.

[FIGURE 6 OMITTED]

CONDITION FOR LIQUID OIL PARTICLES IN CYLINDER TO BECOME AN IGNITER

Figure 7 illustrates a process for a liquid oil particle in the engine cylinder to ignite the air-fuel mixture. Flash point of the oil is the temperature at which the oil gives off vapors that can be ignited with a flame held over the oil if the oxygen required by the flame is available. Flash point can be used as a measure for the oil volatility [21]. Fire point of the oil is defined as the lowest oil temperature at which the oil vapor produced enables supporting combustion once being ignited. In comparison to gasoline, the engine lubrication oil is a fluid with high boiling point and high auto ignition temperature, with the values for these two characteristic temperatures being very close. Flash point, fire point and boiling point are properties for the liquid oil, but the auto ignition temperature is a property of a combustible gaseous mixture. Figure 8 shows the values of fire point, flash point and viscosity at 100[degrees]C for different SAE viscosity grade oils reported in the literature. Note that flash point and fire point for the engine oils are their high-temperature properties, and thus for two-grade SAE oils these properties are similar to those of the corresponding summer-grade oils. In general, the higher viscosity grade the SAE oils, the lower the oil volatility, and the higher the flash and fire points.

Figure 9 shows the estimated probability for the auto ignition and mass of evaporation at different temperatures for 5W-30 synthetic engine oil [22], where the red line is the auto ignition and the dotted blue line is the distillation curve for synthetic 5W-30 oil. It is seen that the auto ignition is governed by the most volatile species in the oil, i.e., the species with lower boiling points.

[FIGURE 7 OMITTED]

[FIGURE 8 OMITTED]

[FIGURE 9 OMITTED]

[FIGURE 10 OMITTED]

With the characteristics shown in Figure 9, it is difficult for the liquid oil particles in the engine cylinder to become an igniter because the oil mist could be vaporized rapidly and the temperature of the liquid oil particles on the walls of the cylinder and combustion chamber may never reach 300[degrees]C due to the water cooling. However, the crankcase oil properties for highly boosted TGDI engines can be altered with fuel dilution, which can be up to 10% or greater due to condensation of the fuel vapor on the cylinder wall, dispersed liquid fuel drops in contact with the cylinder wall, or impingement of the fuel sprays on the piston top [12]. At low engine speeds and high loads, the level of the fuel dilution is high because of more fuel entering the oil as a result of longer fuel spray penetrations due to high fuel demands at low piston speeds, and a low rate of the gasoline evaporation from the oil at relatively low crankcase oil temperatures. Thus, a large fraction of the heavy species in the gasoline entered the oil can stay in it. The auto ignition temperatures as well as representative species in gasoline are presented in Figure 10, where the red line and dotted blue line plot respectively the auto ignition temperatures and contents of the species in the gasoline. The heavy species in gasoline are those with lower auto ignition temperatures than that for the undiluted oil whose auto ignition temperature typically falls in a range between 300 and 350[degrees]C as shown in Figure 9. The ignitability of the diluted oil is governed primarily by that of the most volatile species in the oil, i.e., the gasoline species with low boiling points and low auto ignition temperatures in the diluted oil.

Figure 11 shows impacts of the gasoline content on the flash point (blue line and square points) and the fire point (red line and triangle points) of the engine oil (5W-30). The flash point and fire point were measured following the standards ASTM D3828-12a (method B) and ASTM D92-12b, respectively. It is seen that the flash point and fire point decrease with increase in the gasoline content. The minimum auto ignition temperature of the diluted oil is determined by the most volatile species in the diluted oil--the heavy species of gasoline in the oil, the auto ignition temperatures of which are close to those of diesel fuel. Fuel dilution causes decreases in the temperatures characterizing volatility, flammability and ignitability of the liquid oil particles entering the engine cylinder, making them have a high tendency for self ignition in the cylinder condition at the late stage of the compression stroke.

[FIGURE 11 OMITTED]

[FIGURE 12 OMITTED]

The relationship between the auto ignition temperature of the liquid oil particles entered in the engine cylinder and the frequency of LSPI was investigated experimentally by Takeuchi et al. [23]. They found that the frequency of LSPI increased with lowering the auto ignition temperature of the oil. Based on their data, a relationship between the LSPI frequency and the auto ignition temperatures of the engine oil is plotted in Figure 12. The correlation shown in Figure 12 indicates that there is a strong link between fuel dilution and LSPI.

LSPI CHARACTERISTICS FOR BASE ENGINE OIL

Behavior of LSPI for the base engine oil (5W-30 synthetic) was investigated experimentally at the low-end maximum torque at 1500 rpm (for short, the low end torque), where LSPI was encountered most frequently. In the tests, the engine was operated with the stoichiometric mixture and the engine-out coolant temperature was controlled at 90[degrees]C. LSPI was noticed to occur highly randomly among the engine cylinders, and was with different patterns [11]. The most representative pattern was that the LSPI events (cycles with PFP up to 180 bar) occurred in a train with one event followed by a normal combustion cycle (with PFP lower than 85 bar) alternatively, as shown in Figure 13. For the particular test shown in Figure 13, the abnormal combustion took place in Cylinder 3. The number of LSPI events in the train varied from just a couple of events to more than 10 events, depending on the levels of the dirtiness in the combustion chamber roof and walls of the intake ports.

[FIGURE 13 OMITTED]

[FIGURE 14 OMITTED]

Figure 14 shows the p-V diagrams for normal and abnormal combustions corresponding to the first LSPI event in Figure 13. PFP for the abnormal combustion in Cylinder 3 occurred much earlier than the rest cylinders with normal combustions, and the value of PFP for Cylinder 3 is much greater than those for the other cylinders. Figure 15 compares the mass of fuel burned (MFB) for the super knock combustion in the first LSPI event in Cylinder 3 (the dash line on the left) with that for the normal combustion cycle for the same cylinder just before the first PI event taking place (solid line on the right). Three differences are apparent: 1) the ignition in the cycle with PI is about 24 degCA earlier than that of the normal combustion cycle, as suggested by the first 5% mass of fuel burned (MFB05); 2) in the second half combustion, represented by the 50% mass of fuel burned (MFB50) to the 90% mass of fuel burned (MFB90), the abnormal combustion is much faster than the normal combustion; 3) the location of PFP for the normal combustion cycle is at about 80% mass of fuel burned (MFB80) but that for the abnormal combustion is pretty much at the onset of the super knock. The fuel mass involved in the super-knock combustion is generally less than 10% as shown in Figure 15.

It is not possible to eliminate the LSPI triggers from the engine cylinder; however, intensities of the super knock can be mitigated through weakening the conditions favoring PI in the scavenging zone. It is known from engine combustion control practice that mixture enrichment has two effects: 1) it increases the ignition delay due to slowing down the ignition kinetics and requiring higher ignition energy as a result of decrease in the oxygen concentration; 2) it accelerates the flame speed as long as the excess air coefficient X less than the value corresponding to the maximum flame speed ([lambda] [approximately equal to] 0.75 for turbo-charged gasoline engines). Increasing the ignition delay retards the start of combustion ignited by the liquid oil particles, making the crank angle for PI move to the top dead center (TDC), and acceleration in the flame speed reduces the end gas involved in the knock combustion, both of which mitigate knock intensities.

[FIGURE 15 OMITTED]

[FIGURE 16 OMITTED]

Figure 16 compares cylinder pressure traces for two LSPI events with the engine being operated with a stoichiometric mixture and an enriched mixture with X equal to 0.75 respectively. The engine was operated under the low-end torque with the engine coolant temperature being 90[degrees]C. It is seen that the mixture enrichment did not prevent LSPI but it did mitigate the intensities of knock. Note that for the case with the enriched mixture, LSPI occurred in Cylinder 4, not Cylinder 3 (the pressure trace for Cylinder 2 was not recorded due to a malfunction transducer). The terms of LSPI and super knock should not be used interchangeably because if the flame speed is sufficiently high, the pre-ignition may not lead to knock combustion. Note that pre-ignition stresses on that the mixture is ignited by a difference source before the spark ignition, while knock is an abnormal combustion phenomenon occurring at the late stage of the combustion, only related to a small portion of the mixture known as the end gas whose temperature reaches that for auto ignition before the flame front reaches it. The faster the flame speed, the less the end gas involved in the knock combustion, and the weaker the knock intensity.

LSPI CHARACTERISTICS FOR DIFFERENT OILS

Procedure for LSPI Testing

It was noticed that LSPI was unavoidable when entering the LSPI zone from low speeds but it rarely occurred when entering the same zone from high speeds, as illustrated in Figure 17, where the zone specified by the red line indicates the loads and speeds at which LSPI events are encountered, and the zone for scavenging is indicated by the green line with double dots. The intake and exhaust manifold pressures for the full load curve are also presented in Figure 17. For the engine under study, there existed reverse flows of the hot exhaust gas from the exhaust ports to the intake ports during the valve overlap at engine speeds greater than 2500 rpm, and this hot reversed flow made some liquid oil particles on the intake ports and intake valve backs vaporized; as a result, the effective number of the liquid oil particles entering the cylinder in the scavenging flow followed became less than that when entering the LSPI zone from low engine speeds. For results in Figure 17, the crank oil was the base engine oil.

[FIGURE 17 OMITTED]

In order to understand the influence of different type of the engine crankcase oil on the characteristics of LSPI, six different market available engine oils were tested with the same engine at the low-end torque load point. The oils tested were market available products from two international oil suppliers, covering SAE 0W-20, 0W-30, 0W-40, 5W-20, 5W-30 and 5W-40, with all of them being synthetic. Viscosities, flash points and fire points for these oils agree well with those shown in Figure 8. The investigations were conducted only on the engine operations with a stoichiometric mixture.

LSPI characteristics for the selected oils were tested following a same 5hr-test procedure, covering 3.5hr operations for the "engine conditioning" and 1.5hr operations for the LSPI test. In the conditioning stage, the engine was operated for 2.5 hrs under high loads with 1 hr at 4000rpm with 70% load and 1.5 hrs at the low-end torque, followed by 1hr at idle. After conditioned, the load point of the engine was switched to the low-end torque for the LSPI test. The low-end torque load point was operated twice for different purposes: the first one was for generating hydrocarbon fouling on the intake ports and intake valves, and the second one was for the LSPI test. The LSPI characteristics were studied only when entering the LSPI zone from low speeds. The test on each type of the engine oil was repeated three times and only the worst case was selected for comparison. A correlation between the cylinder pressures and the knock sensor signals was pre-determined for the engine under study, and a threshold for the overpressure in detecting a LSPI event was set based on PFP values in the normal combustion cycles and the maximum PFP values in the spark knock combustions. When the cylinder pressure reached the threshold, the cylinder pressures for 41 cycles were recorded as one data file, with 20 cycles before and 20 cycles after the first detected overpressure cycle. The number of cycles in one recording was selected based on our observations: the LSPI events occurring in a sequence seldom exceeded 10.

LSPI Characteristics for Different Oils

In order to including the influence of the engine coolant temperature on the characteristics of LSPI, the tests were conducted with the two different engine coolant temperatures: 90[degrees]C and 105[degrees]C, respectively. For all the oils tested, fuel dilution levels and flash points were tested after each of the tests. The fuel dilution levels in the duration of the test procedure are shown in Figure 18. The fuel dilution test was conducted following the standard ASTM D352504 (2010), which represents the 95% probability. The flash points for the diluted oils fell in a range between 87 and 97[degrees]C, with the 0W oils having higher flash points than the 5W oils. These values are about 150[degrees]C lower than the fresh oils [24], suggesting that volatility and ignitability of these oils be influenced considerably by the fuel dilution.

[FIGURE 18 OMITTED]

The results for some oils with poor repeatability of the LSPI events due to unknown reasons were not taken for comparison. Selected test results are presented in Tables 3 to 6. The results indicate that the behavior of LSPI is highly random. As can be seen that 0W oils are not necessary to be better than 5W oils, and there is no clear trend for the influence on LSPI of the oil viscosity or the engine coolant temperature. In our previous tests on the base engine oil [11], the frequency of LSPI was observed to decrease with increasing the coolant temperature. However, in this investigation, the influence of the engine coolant on LSPI was not apparent.

Selected cases for illustrating the random behavior of LSPI are given in the following. Figure 19 shows a LSPI test with the engine lubricated with 0W-30 (supplier-1 product) and the coolant temperature being 105[degrees]C. In this particular data recording, the LSPI event train had 12 events, with 11 of them associated with superknock (cycles with high PFP values). Figure 20 presents the result of a repeating test under the same condition. In this case, only a single LSPI event was detected in a different cylinder, and the preignition did not lead to knock combustion. Figure 21 compares the cylinder pressure trace for the first LSPI event in Figure 19 with that for the isolated LSPI event in Figure 20. In the repeating test, the cylinder pressure fluctuations are negligible as shown in the right chart in Figure 21. Regardless a LSPI event leads to superknock or not, it still should be classified as abnormal combustion because its pressure rising rate after start of combustion and PFP are much greater than those in the normal combustion cycles, and thus engine vibrations will be different from those in the normal combustion cycles. This is also the mechanism for detecting the LSPI events with the engine knock sensor.

[FIGURE 19 OMITTED]

[FIGURE 20 OMITTED]

[FIGURE 21 OMITTED]

[FIGURE 22 OMITTED]

Figure 22 compares the cylinder pressure traces for a LSPI test (left chart) and those for a repeating test (right chart) under the conditions with the engine lubricated with 0W-20 (supplier-2 product) and the oil temperature being 105[degrees]C. In both tests, only an isolate LSPI event was detected. Although occurred in the same cylinder in these two tests, the LSPI event in the repeating test did not lead to super knock as shown in the right chart in Figure 22.

We noticed in this investigation that although LSPI occurred frequently as long as the engine load and speed fell into the LSPI zone, the behavior of LSPI was different and the event often occurred in different cylinders. It was difficult to reproduce the same LSPI pattern in the same cylinder with the engine operated under the same conditions. This suggests that LSPI be triggered in a complicated condition with contributions from many variable parameters, related to the intake flow, the exhaust flow, physical conditions of the liquid oil particles entering the engine cylinder, the number density of the liquid oil particles in the blowby recirculation, the scavenging duration and flow rate, the level of hydrocarbon fouling in the intake system, etc. It is only meaningful to characterize the behavior of LSPI in a statistical sense.

Impact of Hydrocarbon Fouling on Intake Valves and Ports

It was noticed in the tests that LSPI occurred mainly in the scavenging zone on the engine map given in Figure 17. As was aforementioned, in the scavenging zone, hydrocarbon fouling or carbon deposits can be significant on the intake ports as well on the back and stem of the intake valves. Figure 23 shows a LSPI test with the engine oil being 0W-20 (supplier-1 product) and the coolant temperature being 105[degrees]C. In this test, 13 LSPI events (cycles with PFP values about 150 bar) occurred in the event train in Cylinder 4, with all of them leading to superknock. The number of LSPI events in the event train was the highest among all of the LSPI tests that we conducted so far.

[FIGURE 23 OMITTED]

In order to investigate the impact of the hydrocarbon fouling in the intake system on LSPI, the black, sticky, sluge-type hydrocarbon fouling on the inner surface of the outlet pipe of the intercooler as well as on the walls the intake manifold and intake ports was wiped out with towels with removal of the intake manifold assembly from the engine. After this cleaning action, the intake assembly was reinstalled then the test was restarted under the same engine operation conditions. The harder hydrocarbon fouling on the intake valves was not touched being afraid of that the falling offs could enter the engine cylinder. The result of the test with the partially cleaned intake system is presented in Figure 24. It is seen that although the intake system cleaning action did not eliminate LSPI, there were only three LSPI events in the event train and they occurred in Cylinder 1, with Cylinder 4 behaved normally. In all the tests on other oils with the partially cleaned intake system, LSPI occurred rarely, and once occurred the number of the LSPI events in the event train became much less. Due to the random nature of LSPI, it may not be concluded that the triggers for LSPI were originated from the oil loading in the blowby recirculation; however, it can be stated based on our tests that the hydrocarbon fouling in the intake system has a strong influence on the LSPI events in the event train, i.e., how many LSPI events occur in a sequence when LSPI is encountered.

[FIGURE 24 OMITTED]

SUMMARY

An experimental investigation was conducted on the influence of the crankcase oil properties on the engine combustion in the LSPI zone with a highly boosted 1.5L TGDI engine. The engine oils tested covered SAE 0W-20, 0W-30, 0W-40, 5W-20, 5W-30 and 5W-40. In the tests, the fuel dilution levels reached 5.3 to 6%. With these levels of the fuel dilution, the flash points for the diluted oils dropped by about 150[degrees]C, indicating that the properties of the crankcase oil were altered by the fuel dilution. Since the gasoline species were the most volatile and ignitable components in the diluted oils, the volatility and ignitability of the diluted oils differed from those of the fresh oils significantly. There was no clear indication on which SAE oil tested had a stronger influence on LSPI than other oils, either promoting or inhibiting LSPI. This may be due to that the influences on LSPI of the related properties for the different oils might not be as strong as that of the gasoline content in the diluted oils. For any tested oil, it was difficult to reproduce the same LSPI pattern in the same cylinder with the engine operated under the same conditions. This suggests that LSPI be triggered in a complicated condition with contributions from many variable parameters, related to the intake flow, the exhaust flow, physical conditions of the liquid oil particles entering the engine cylinder, number density of the liquid oil particles in the blowby recirculation, the scavenging duration and flow rate, the level of hydrocarbon fouling in the intake system, etc. It may be only meaningful to characterize the behavior of LSPI in a statistical sense.

Ho Teng, Xuwei Luo, Tingjun Hu, Ruigang Miao, Min Wu, Bin Chen, and Fanhua Zeng

Jiangling Motors, Co., Ltd

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[13.] Welling, O., Collings, N., Williams, J., and Moss, J., "Impact of Lubricant Composition on Low-speed Pre-Ignition," SAE Technical Paper 2014-01-1213, 2014, doi:10.4271/2014-01-1213.

[14.] Dingle, S., Cairns, A., Zhao, H., Williams, J. et al., "Lubricant Induced Pre-Ignition in an Optical SI Engine," SAE Technical Paper 2014-011222, 2014, doi: 10.4271/2014-01-1222.

[15.] Morikawa, K., Moriyoshi, Y., Kuboyama, T., Yamada, T. et al., "Investigation of Lubricating Oil Properties Effect on Low Speed Pre-Ignition," SAE Technical Paper 2015-01-1870, 2015, doi:10.4271/201501-1870.

[16.] Moriyoshi, Y., Yamada, T., Tsunoda, D., Xie, M. et al., "Numerical Simulation to Understand the Cause and Sequence of LSPI Phenomena and Suggestion of CaO Mechanism in Highly Boosted SI Combustion in Low Speed Range," SAE Technical Paper 2015-01-0755, 2015, doi:10.4271/2015-01-0755.

[17.] Morikawa, K., Moriyoshi, Y., Kuboyama, T., Yamada, T. et al., "Investigation of Lubricating Oil Properties Effect on Low Speed Pre-Ignition," SAE Technical Paper 2015-01-1870, 2015, doi:10.4271/201501-1870.

[18.] Boese, D., Ritchie, A., and Young, A., "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)," SAE Technical Paper 2016-01-0716, 2016, doi:10.4271/2016-01-0716.

[19.] Ritchie, A., Boese, D., and Young, A., "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," SAE Int. J. Engines 9(2):832-840, 2016, doi:10.4271/2016-01-0717.

[20.] Long, Y., Wang, Z., Qi, Y, Xiang, S. et al., "Effect of Oil and Gasoline Properties on Pre-Ignition and Super-Knock in a Thermal Research Engine (TRE) and an Optical Rapid Compression Machine (RCM)," SAE Technical Paper 2016-01-0720, 2016, doi:10.4271/2016-01-0720.

[21.] Ishida, H. and Iwama, A., "Some Critical Discussions on Flash and Fire Points of Liquid Fuels," Fire Safety Science: Proceedings of the First International Symposium, 218-226, 1986.

[22.] Hu, T., Teng, H., Luo, X., Lu, C. et al., "Influence of Fuel Dilution of Crankcase Oil on Ignitability of Oil Particles in a Highly Boosted Gasoline Direct Injection Engine," SAE Technical Paper 2015-01-2811, 2015, doi:10.4271/2015-01-2811.

[23.] Takeuchi, K., Fujimoto, K., Hirano, S., and Yamashita, M., "Investigation of Engine Oil Effect on Abnormal Combustion in Turbocharged Direct Injection--Spark Ignition Engines," SAE Int. J. FuelsLubr. 5(3):1017-1024, 2012, doi:10.4271/2012-01-1615.

[24.] Luo, X., Teng, H., Hu, T., Miao, R. et al., "Mitigating Intensities of Super Knocks Encountered in Highly Boosted Gasoline Direct Injection Engines," SAE Technical Paper 2015-01-0084, 2015, doi:10.4271/201501-0084.

CONTACT INFORMATION

Ho Teng

Chief Engineer in Engines

Jiangling Motors Co., Ltd

Phone: +86 791 8526-7012

hteng1@jmc.com.cn

ACKNOWLEDGMENTS

The authors thank colleagues of the gasoline engine team at JMC for helps during the engine tests on LSPI and Shanghai Oil Gas & Chemicals Testing Center of SGS for conducting the crankcase oil property measurements.

ABBREVIATIONS

BDC--Bottom dead center of piston

BMEP--Brake mean effective pressure

PI--Pre-ignition

LSPI--Low speed pre-ignition

MFB--Mass of fuel burned

MFB05--5% of mass of fuel burned

MFB50--50% of mass of fuel burned

MFB90--90% of mass of fuel burned

PFP--Peak firing pressure

TDC--Top dead center of piston

TGDI--Turbocharged gasoline direct injection

VVT--Variable valve timing

Table 1. Basic parameters for the TGDI engine
under study.

Engine configuration                    14
Engine displacement                    1.5L
Bore                                  79 mm
Stroke                                76 mm
Compression ratio                     9.5:1
Number of valves per cylinder           4
Fuel injection equipment         Direct injection
Max injection pressure               150 bar
Injector mounting                  Side mounted
Fuel                              RON93 gasoline
Turbo flow control                  Waste gate

Table 2. Selected properties of engine crankcase oil.

Oil grade                                 5W-30
Density @ 15[degrees]C [kg/L]             0.852
Viscosity @ 100[degrees]C [cSt]           11.7
Viscosity @ 40[degrees]C [cSt]            67.5
Total base number TBN [mg-KOH/g]           10
Flash point [[degrees]C]                   229
Noack volatility @ 250[degrees]C [wt%]    < 10

Table 3. Oils from supplier-1, engine coolant temperature
= 90[degrees]C.

SAE grade                  0W-30   0W-40   5W-20   5W-30   5W-40

#PI in event train           1       7       2       1       1
#PI w/ superknock            1       6       1       1       0
#PI w/o super knock          0       1       1       0       1
[PFP.sub.max] [bar]        125     155     130     125     115

Table 4. Oils from supplier-1, engine coolant temperature
= 105[degrees]C.

SAE grade                  0W-20   0W-30   0W-40   5W-30

#PI in event train          13      12       4       6
#PI w/ superknock           13      11       3       6
#PI w/o superknock           0       1       1       0
[PFP.sub.max] [bar]        155     155     155     155

Table 5. Oils from supplier-2, engine coolant temperature
= 90[degrees]C.

SAE grade                0W-40   5W-20   5W-30   5W-40

#PI in event train          1       1       1       1
#PI w/ superknock           0       1       0       1
#PI w/o superknock          1       0       1       0
[PFP.sub.max] [bar]       115     125     115     150

Table 6. Oils from supplier-2, engine coolant temperature
= 105[degrees]C.

SAE grade                0W-20   0W-30   0W-40   5W-20   5W-30   5W-40

#PI in event train         1       1       8       2       6       3
#PI w/ superknock          1       0       7       1       6       2
#PI w/o superknock         0       1       1       1       0       1
[PFP.sub.max] [bar]      150     110     155     135     155     155
COPYRIGHT 2016 SAE International
Copyright 2016 Gale, Cengage Learning. All rights reserved.

2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!

SHOdded

And now ... Commercial Break! :P

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QuoteNOV 9, 2016 3:12 PM
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The new product was created in order to help car owners maintain a clean, efficient engine. Without proactive cleaning using an effective intake valve cleaner such as Max-Blast, engines are susceptible to formation of IVD's. This is especially the case with GDI (Gasoline Direct Injection) engines, which form coked, stubborn-to-remove IVD's. Accumulation of IVD's can lead to power loss, increased emissions, reduced fuel economy, rough idle, harder starts and misfire codes.

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! No longer available
2007 Ford Edge SEL, Powerstop F/R Brake Kit, TXT LED 6000K Lo & Hi Beams, W16W LED Reverse Bulbs, 3BSpec 2.5w Map Lights, 5W Cree rear dome lights, 5W Cree cargo light, DTBL LED Taillights

If tuned:  Take note of the strategy code as you return to stock (including 3 bar MAP to 2 bar MAP) -> take car in & get it serviced -> check strategy code when you get car back -> have tuner update your tune if the strategy code has changed -> reload tune -> ENJOY!