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That has very little to do with the question.
LSPI Concern for GDI Non - Turbo Engine ?
- Thread starter ChrisD46
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MB229.5 and its counterparts, has its own lspi test.
I would be more concerned with buildup on the intake valves.
Why would you stay away from E10 fuels? Ethanol is literally the solution to LSPI with higher octane and a couple % slower burn.
IE 91 + 20% E85 and you will def not have LSPI
I would be more concerned with buildup on the intake valves.
Why would you stay away from E10 fuels? Ethanol is literally the solution to LSPI with higher octane and a couple % slower burn.
IE 91 + 20% E85 and you will def not have LSPI
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Not really.
SP addresses chain wear from Direct Injection (NA or FI) and LSPI from TGDI. The vast majority of DI engines have turbochargers so a modified Ford Ecoboost is used for these tests.
E10 or E85 mitigates LSPI? Can you link anything to that? I have not seen any correlation between LSPI and octane nor fuel composition. In fact the studies I have seen show no correlation between octane rating and LSPI.
"Fuel burn" is not related to LSPI, or at least I have never seen a study or paper that shows it is.
Ethanol will not at all mitigate lspi. It actually makes it worse in studies. This is likely one of the reasons it's seen more in the USA. Neither will thicker oils like the other person said.
The only way currently we have to mitigate lspi is to massively drop calcium (and some raise zinc but most do not)
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I would argue that the superknock would be more difficult to acheive with higher octane fuel as it is more difficult to ignite. Understanding that LSPI is related to build up on the pistons, higher octane could not hurt. I have noticed that SP has WAY lower calcium than SN.
It is really a ******** thing really, just get rid of the sorry small turbos DI engines and go back to 1980s-90- civic which got 35+ mpg and call it a day.
The purpose of me asking this question in my original reply to this post was, I have a 2020 chevy truck with the L8t 6.6, and thinking about running a 0w40 or 5w40, and wondering if the L8t could be effected by LSPI, even though it is not turbo.
@kschachn & @bhvrdr
1. Ethanol has less energy, ie lower temperature.
2. Ethanol has higher octane, does not combust (IGNITE) as easily.
3. Ethanol (E85) burns slightly slower, so even if pre-ignition occurs the effect is dampened.
4. You only need 20-30% Ethanol to reach substantially higher effective octane number.
5. Ethanol leaves less soot, one concern for LSPI.
I dont even have too look up studys, common sense knows what they will find.
Here is a quite recent american one anyway.
Note that they deactivated the piston "oil cooling jets" in the GM DI 2.0T engine.
"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."
What studies are you guys referring to that points to etanol worsening LSPI?
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This study however shows once past 30 percent the superknk decreases and at 50 percent does not occur...
Numerical Analysis of Low Speed Pre-Ignition and Knock Process in Downsized Turbocharged Direct Injection Engines with Ethanol-Gasoline Blends - International Journal of Automotive Technology
The feasibility of the calculation model and calculation methods is verified by engine bench test and visual rapid compression machine (RCM) test as reported in this paper. Using AVL software FIRE, the processes of low speed preignition (LSPI) and super knock triggered by the oil particles have...
link.springer.com
This study however shows once past 30 percent the superknk decreases and at 50 percent does not occur...
Numerical Analysis of Low Speed Pre-Ignition and Knock Process in Downsized Turbocharged Direct Injection Engines with Ethanol-Gasoline Blends - International Journal of Automotive Technology
The feasibility of the calculation model and calculation methods is verified by engine bench test and visual rapid compression machine (RCM) test as reported in this paper. Using AVL software FIRE, the processes of low speed preignition (LSPI) and super knock triggered by the oil particles have...
Whats EEE EB25 2MB25 and CP25?
Also downsized as in less then 1.5L ?
My question is HOW?
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Ahh Ford 1.6 thats how
And also this
" Therefore, to aid in increasing the probability of LSPI, the GDI injector was rotated 45° about its centerline to increase wall impingement by directing some of the fuel spray towards the wall. Fig. 1 also depicts this rotated injector orientation."
They ****ed about with the injector to spray at the cylinder walls.
Ethanol needs higher volume of fuel so..... i would disregard that study.
And if you have washed cylinder walls LSPI would not be my main concern.
U got any more of them studys?
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l8t is without turbo, so i suppose I am good, this is the consensus?
Yes
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I know an individual who possesses a profound fascination with engines. He immerses himself in their intricacies, meticulously disassembling them and engrossing himself in the accompanying documentation. Recently, he developed an interest in the history of LSPI and how it made an unexpected entrance in 2010. To his surprise, he even discovered the names of two key figures (Terrence & Chris, SwRI) behind this phenomenon, with Terrence Alger emerging as the primary evangelist. SwRI, a reputable company, played a pivotal role in LSPI inception. You can easily find more details with a quick online search.
Curiously, my acquaintance remains skeptical about the possibility of LSPI. He firmly believes that modern engine control units (ECUs), equipped with ion and knock sensors, can swiftly detect such issues. Consequently, the ECUs promptly cut off fuel supply to prevent any damage, triggering an emergency mode. This perspective holds some truth. Advocates of LSPI argue that the ECU supposedly requires prolonged detonation to consider the signal stable enough for a response. It's difficult to ascertain the absolute truth of this matter.
It's worth noting that the ignition-inducing properties of certain metal compounds present in oils have been recognized for quite some time. Studies ( https://saemobilus.sae.org/content/720153 ) as early as 1972 or 1973 explore the effect of these compounds on sudden ignition. However, since then, computer control systems for internal combustion engines have undergone significant changes, incorporating features like ionic and detonation sensors, among others. This progress leads us to question whether the LSPI issue has been exaggerated.
Moreover, it's important to acknowledge that not all engines are susceptible to LSPI. In fact, some oil manufacturers confidently claim that their products are entirely immune to such occurrences. Despite this, isolated incidents persist, such as the well-documented problem with Mercedes pistons and, of course, Ford - with any oils.
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An ECU you can not protect from low speed pre ignition. Otherwise it would not be one of the leading causes of modern small displacement turbo gdi engines....and it is.
I've calibrated multiple different types of ecu's and I'm familiar with ignition knock control routines as well as how to modify them.
Even some of the absolute best ignition knk control strategies from Simos and Bosch ala Audi and Porsche that can run timing advance that could take advantage of up to 98 octane relying on the IKC to keep the engine at peak timing will do nothing to stop lspi.
Unlike regular detonation, lspi can literally occur immediately and without ongoing lspi that would trigger knk sensor control.
In other words, if you get 1 bad enough incident of superknock and the knk sensor picks it up it's already too late.
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Indeed, I presented these very arguments to him, as they are widely recognized.
I emphasized that by the time the knock sensor detects any issue, it may already be too late, as the computer system is configured to respond differently. However, it's crucial to remember that the knock sensor alone doesn't hold all the answers. We must also consider the presence of an ion sensor, which plays a significant role in safeguarding the engine. It's evident that a few isolated knocks wouldn't possess enough strength to cause catastrophic damage. Therefore, it stands to reason that a series of such occurrences would need to transpire in order to pose a genuine threat.
The the other point to be made to him is that the not control strategy in the presence of spark knock is to initiate timing retard to prevent further spark knock.
Timing retard doesn't reduce lspi though. It can actually make it worse. Remember LSPI occurs prior to the spark.
Thats pure and utter bullcrap. Retarding timing ofc would not mitigate PRE IGNITION.
Ever heard of ecu controlled boost? Modern engine could even control rpm's if the gearbox is automatic. LSPI can definitively be avoided with automatics.
Saab had boost controlled anti knock since 1982. And refined it with T5 and T7 in the 90's with knock sensor in each cylinder.
"The numerical prefix 'tri-' in Trionic. 'Ion' comes from the fact that it uses ion current, measured by the spark plugs between combustion events which acts as a sensor for knock, misfire and synchronization detection. The ion current stream which was developed within the ion sensing system due to combustion can be deduced by monitoring the secondary current of the ignition coil. Using the value and wave shape of the current, after the actual spark event, the quality of the actual combustion process is determined,"
Automatic Performance Control - Wikipedia
Why LSPI is a new concern probably has to do with higher compression-ratios and low friction piston rings, but thats just my guess.
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I think the issue is that the conditions that produce LSPI (low engine RPM, higher load, high boost) were a result of the pursuit of fuel economy (avoiding a down shift and higher RPM). This is arguably why we didn't see it "become a thing" with early TGDI offerings from VAG for example, as their programming precluded this operating regime from producing the necessary conditions.Thats pure and utter ********. Ever heard of ecu controlled boost? Modern engine could even control rpm's if the gearbox is automatic. LSPI can definitively be avoided with automatics.
Saab had boost controlled anti knock since 1982. And refined it with T5 and T7 in the 90's.
Automatic Performance Control - Wikipedia
en.wikipedia.org
Why LSPI is a new concern probably has to do with higher compression-ratios and low friction piston rings, but thats just my guess.
When we saw mega-downsized mills with thimble pistons and lots of boost appear on the scene, trying to act like bigger engines and mated to cars more tailored for economy and subsequently programmed as such, this is when LSPI seemed to emerge and garner attention.
Thats pure and utter ********. Ever heard of ecu controlled boost? Modern engine could even control rpm's if the gearbox is automatic. LSPI can definitively be avoided with automatics.
Saab had boost controlled anti knock since 1982. And refined it with T5 and T7 in the 90's.
Automatic Performance Control - Wikipedia
Why LSPI is a new concern probably has to do with higher compression-ratios and low friction piston rings, but thats just my guess.
You seem to be confusing lspi with spark knock.
...and misunderstanding ECU and TCU IKC systems as well as how "rpms are controlled".
First, it is the TCU that determines shift points not the ECU.
Second, the ECU in all modern cars (since the 1990s) control boost via wastegate control and managed by load and torque lookup tables.
But let's talk about how the ECU can mitigate against spark knock versus lspi.
There are no ECU algorithms currently that even reliably detect lspi. This is not spark knk.
Second, if the ECU was detecting spark knock and retarded timing lspi would not be mitigated.
Low speed pre-ignition knock detection, mitigation, and driver notification | TREA
Explore innovation relationships and map ideas to the unified knowledge graph
trea.com
LSPI knock is often one or more orders of magnitude greater in intensity than spark knock. A typical knock control strategy is spark retardation. This control strategy, however, is not effective against LSPI knock and is actually detrimental in mitigating LSPI knock. This is because during LSPI knock, combustion has already been initiated prior to the spark discharge, and thus retardation of the spark timing provides the cylinder charge even more time for auto-ignition to occur.
This is exactly what causes lspi.
You have small displacement engines with small turbochargers on them that make boost literally off idle. I can show you 26psi of boost on my bone stock turbo logs by 2000rpm. Add 3psi to the below for manifold boost
This gives drivers that nice feel of being able to punch the car around in traffic doing light throttle passing. Even 30 and 40% throttle pedal inputs can get you full boost request. This is also the zone that manufactures would like to keep you in to be getting good fuel economy and making people happy about those fuel economy numbers.
Then you have these small turbos making less boost up top where fuel economy would be at its worst. But no lspi occurs up there.
Then you add to this 8-speed 9-speed and 10 speed automatic transmissions that will try to keep the car at 1200 RPM or even below at almost any speed that you could legally cruise at.
When you used to have four-speed transmissions people were cruising around at 70 mph and 2,800 RPM.
Now you can cruise around at 80 mph and 1200 RPM.
This creates a very rich environment for lspi.