castrol

[SR5]

Originally Posted by Gokhan

It explains LSPI very well -- you probably didn't fully understand it either before you saw it, like the direct injection mixing the oil with the fuel and lowering the autoignition temperature;.


Originally Posted by Shannow

Nope, I got it...I did all the IC engine theory subjects I could take...when I did my engineering degree, including emissions theory, oil and fuel adsorption and desorption on cylinder walls, and teh behavior of crevice volumes...



Originally Posted by Gokhan

OK, you figured out the LSPI phenomenon before any scientists did, who actually spent a long time trying to understand it and had some success only very recently. Why didn't you publish a paper on it?


Gokhan he never said that. Shannow just said that he understood the concept before you explained it to him. You sometimes write in a style as if something doesn't exist until you discover it, and then you need to explain it to us like we can't work it out for ourselves.

Please try and write posts with less ego, it makes it difficult to read your posts.

 

[bbhero]

Humility....

Something missing in this world more and more....

And I heard someone last pm say something I found rather profound about this. Made me think myself. And how maybe I need to handle some circumstances different at times.

 

[Gokhan]

Originally Posted by SR5
Gokhan he never said that. Shannow just said that he understood the concept before you explained it to him. You sometimes write in a style as if something doesn't exist until you discover it, and then you need to explain it to us like we can't work it out for ourselves.

Please try and write posts with less ego, it makes it difficult to read your posts.

Originally Posted by bbhero
Humility....

Something missing in this world more and more....

And I heard someone last pm say something I found rather profound about this. Made me think myself. And how maybe I need to handle some circumstances different at times.

If you go back and read what was posted, I was being very nice and kind to him after he trolled me about a post I made a year and a half ago when I made an innocent post in the current thread -- this is what he does, frequently trolls me out of the blue over irrelevant old posts going as far back as a decade that should be closed matter -- but then instead of leaving it there or replying nicely, he eventually went as far as saying I was "in the habit of making stuff up that fits my imaginings, posting it as fact, and then dying in the trenches over it." I don't know how he comes up with these words -- in a way they are actually funny because they are so over-the-top.

I should know better by now not to be provoked by his childish antics.

 

[bbhero]

Candidly...

I think you both need to settle in and settle down... You both are very, very, very intelligent people. You both add a lot of very good information on here. Just don't allow commentary to get personal.

You both are good guys. . So... Be better to each other.

And stay a bit humble...

 

[Garak]

The thing is, Gokhan, is they're not irrelevant. If you say one thing at one time and are absolutely convinced of it, then some months later say something absolutely opposite to that with no explanation as to why your view is now different, you're going to get called on it. I'm wrong all the time. However, if we have some revelation of that along the way, it's good to show the thought process, rather than handing out, hypothetically, one set of advice to one problem a year ago, then one year later recommending something that's the exact opposite, with no apparent rhyme or reason.

It isn't an antic if it got you to start discussing it. If he wouldn't have pointed out the gap in your statements, I would have.

I have zero doubt whatsoever that you've experienced detonation in your Corolla. I've seen it happen frequently on older vehicles, too. That doesn't make it LSPI, which isn't quite the same. At least we can agree that it's not predetonation.

The pinging you get in your Corolla was mostly solved with more advanced engine controls. That hasn't been the case with LSPI. If they were the same thing, the same solutions would work, right?

 

[Gokhan]

You need to understand what low-speed preignition (LSPI) is, beyond the acronym people are accustomed to. I post its illustration again:

(1) The damage is actually not caused by the preignition event itself but it's caused by the "super knock" detonation that follows it after the spark ignition.

(2) The reason why the super knock occurs is the high-power density of the engine, specifically the high turbo boost.

(3) Preignition is likely caused by the oil additives (in particular the calcium detergent) that lower the autoignition temperature of the fuel.

(4) Preignition is likely aided by the direct injection, which increases the mix of the oil into the fuel. However, it can also happen in port-injection engines to a lesser extent.

Basically, the LSPI event is very similar to detonation that would be caused in a highly boosted engine by advancing the spark timing too much -- you get a much more violent detonation because of the high turbo boost than you would get in a naturally aspirated engine but preignition also seems to lead to even a more powerful knock than advancing the timing.

At the end of the day, preignition and detonation are the same phenomena that happen in every other engine. The question is why and how they happen in TGDI or some other high-power-density turbocharged engines with port injection.

Again, at the end of the day, both preignition and detonation are autoignition and they are determined by the autoignition temperature of the gasoline - air - oil - carbon particles mixture as well as the temperatures in the engine. Since temperatures in highly boosted engines or other high-power-density engines can be very high, this is why LSPI happens in these engines and why the detonation can be so violent.

Current postulate in the industry is that LSPI can be mitigated by carefully choosing the oil additives, as they seem to be the main reason behind the preignition. In addition engine design is also crucial.

Coming back to the Corolla, both 1985 Corolla and 2009 Corolla had the exact same low-speed pinging on occasions -- so, it's not an old vs. modern Corolla thing. While I agree that there is probably preignition, it can't always be ruled out. I do advance the spark timing beyond the factory specs, which is causing it in the 1985 Corolla. So, advancing the ignition timing is simulating preignition, which is followed by light knock. You can call it "low-speed detonation with advanced ignition timing simulating preignition."

As for whether SN PLUS oils help non-LSPI preignition and detonation in other engines, I think this is quite possible. As I said it's all about autoignition and if a better oil increases the autoignition temperature, that would help reduce pinging in any engine at least when the oil is a factor. This is just like higher octane gas would reduce LSPI in TGDI engines as well as pinging in other engines.

This seems to be a good article on the relation between preignition and the subsequent detonation:

https://journals.sagepub.com/doi/10.1177/1468087414530388
Relationship between super knock and preignition
Zhi Wang, Hui Liu, Tao Song, Yunliang Qi, Xin He, Shijin Shuai, and JianXin Wang
State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing, China

"However, preignition/super knock tends to occur at low-speed, high-load conditions, which is the main obstacle for improving power density and fuel economy. ... Super knock is the severe engine knock triggered by preignition. Preignition may lead to super knock, heavy knock, slight knock, and nonknock. Significantly advancing spark timing can only simulate preignition, not super knock. Although knock intensity tends to increase with earlier preignition timing, higher unburned mixture fraction at start of knock, and higher temperature and pressure of the unburned mixture at start of knock, knock intensity cannot be simply correlated to any of the parameters above."

So, there are similarities in LSPI in TGDI engines and the low-speed detonation in Corollas in that (1) they both occur in low-speed, high-load conditions and (2) they both need an ignition event that comes in well advance of the top dead center. The differences are that (1) in the Corolla the too-far-advanced ignition is caused by the spark vs. in the TGDI engine likely by the oil additives and (2) in the TGDI engine the detonation is a super knock likely because of the super boost and perhaps some other factors as well vs. in the Corollas it's only a light knock due to the lack of boost and lower cylinder temperatures and pressures.

This article discovered that the fuel composition greatly affects LSPI events, even when the octane rating is the same:

https://www.sciencedirect.com/science/article/pii/S0016236118308858

More about LSPI vs. autoignition here, base-oil type also being a factor:

https://www.infineuminsight.com/articles/passenger-cars/lspi-and-lubricant-auto-ignition/

 

[Garak]

That's all correct, but deflection from the issue at hand. The simplest solutions to ordinary pinging in a vehicle, such as your Corolla, are to increase octane or retard timing. The latter is generally done by an acoustical sensor. Changing to an LSPI friendly oil isn't going to be a solution to an acute pinging problem.

The one thing that has even the slightest bit of similarity is that carbon deposits can exacerbate ordinary pinging. Ordinary pinging has almost been completely defeated thanks to modern knock sensors. I haven't heard a pinging event in a car that's been manufactured in the last twenty years. At least up here, oil companies were, before modern knock sensors became the norm, advising to run mid grade in older cars, if pinging would appear and they used to run fine on regular.

With LSPI, if it were enough to increase octane or retard timing on demand, the OEMs would have done so and we would have heard nothing about this. Those things aren't the answer and the problem is more complex.

 

[Gokhan]

Actually, the problem is neither more complex nor that different in nature. What makes the real difference in the TGDI engines is the "super knock" that sometimes follows the preignition, which can damage the engine. Super knock has to do with the highly boosted engine among other things. Also, you can retard the spark advance to easily reduce or eliminate the knock in conventional engines if that's what's causing the knock but when preignition is what is causing the knock, that's harder to deal with in any kind of engine -- TGDI or conventional.

The low-speed light knock I have experienced happens exactly in the same way in both the SOHC carbureted 1985 Corolla and the brand-new DOHC dual VVT-i 2009 Corolla I owned at one point -- producing exactly the same "frying" sound in exactly the same driving conditions -- gentle merging on the freeway on the same ramp.

I will write down the similarities and differences between the TGDI LSPI and the Corolla low-speed light knock:

(1) They both happen in low-speed, high-load conditions and they are both unpredictable, as many variables affect them.

(2) Both are caused by an ignition event that happens somewhat too early.

(3) Both can be mitigated by tuning the engine parameters. In the TGDI case this would be to reduce the boost among other things. However, in either case this is not desirable because doing so results in lower horsepower and lower fuel economy.

(4) Both can be mitigated to some extent by using higher-octane fuel. However, chances are that the TGDI engines already spec the highest-octane fuel available.

(5) In the Corollas the initiating event is the somewhat too advanced ignition timing. In TGDI engines the initiating event is preignition caused by some hot spot, postulated to be an oil additive like calcium detergent in the air - fuel - oil mixture but it's not known exactly.

(6) Perhaps the biggest difference is that in a properly tuned Corolla, the knock is light and harmless. However, in a TGDI engine you may get a super knock in some occasions, which could damage the engine. This has to do with the high turbo boost among other variables.

(7) Since oil is a main factor in LSPI, it is postulated that LSPI can be mitigated to a good degree by optimizing the oil chemistry, especially the additives. It's not clear if these LSPI-optimized oils (such as API SN PLUS) also help with the low-speed light knock in conventional engines. Since these optimized oils have a higher autoignition temperature, it's possible that they could help with conventional preignition and knock as well, depending on how much the oil is a factor in these events, which could be important in engines with high oil consumption.

All this said I just ran into a great 35-page-long review article on the LSPI subject, which has open access under the Creative Commons license, for those who are interested and have time. Enjoy!

https://www.sciencedirect.com/science/article/pii/S0360128516300764
Knocking combustion in spark-ignition engines
Zhi Wang (a), (b) Hui Liu (a) Rolf D Reitz (c)
(a) State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing, 100084, China
(b) Center for Combustion Energy, Tsinghua University, Beijing 100084, China
(c) Engine Research Center, University of Wisconsin-Madison, Madison, WI 53706-1687, USA
Received 17 July 2016, revised 29 March 2017, accepted 29 March 2017, available online 3 May 2017

 

[Garak]

Despite the charts, we still have no answer for the elephant in the room. There obviously is a quantitative difference since ordinary knock sensors are unable to eliminate this problem. Turbo gasoline engines requiring premium are not new. I had one from the 1991 model year. It had a knock sensor. In fact, some complained the knock sensors were so sensitive that you would lose power over extremely rough roads or with really problematic motor mounts.

 

[Gokhan]

Originally Posted by Garak
Despite the charts, we still have no answer for the elephant in the room. There obviously is a quantitative difference since ordinary knock sensors are unable to eliminate this problem. Turbo gasoline engines requiring premium are not new. I had one from the 1991 model year. It had a knock sensor. In fact, some complained the knock sensors were so sensitive that you would lose power over extremely rough roads or with really problematic motor mounts.

Read the review article I linked if you are interested in LSPI. It is 35-page-long but summarizes everything known about LSPI.

Here is an excerpt from the end of the article regarding your question of knock control with LSPI in TGDI engines, which is ongoing research (posted under the Creative Commons license):

6.2.2. Detonation suppression and utilization

Super-knock is at present the major challenge for improving the power density in IC engines, not only for SI combustion, but also for HCCI combustion and dual fuel combustion if the premixed mixture concentration is high enough. A premixed charge is actually to some degree inhomogeneous in an engine combustion chamber, and this is likely to influence a developing detonation. There are two approaches to suppress super-knock. One is to eliminate pre-ignition sources, and the other is to avoid super-knock (detonation initiation). When a BMEP of up to 25 bar is desired in production engine, eliminating random pre-ignition becomes more-and-more of a challenge, and avoiding destructive detonation will be paid more attention. This may proceed by eliminating the transmission routes of shock waves, or by damping their amplitudes so as to suppress super-knock even with a pre-ignition (e.g., organizing a strong gradient of temperature and concentration, or introducing reaction inhibitors to prevent a shock wave coupled with heat release). Suppressing detonation prevents damage to the internal combustion engine, and the methods to be explored could also benefit industrial safety (e.g., preventing mine gas explosion and dust explosion accidents).

Since most detonations are initiated near the walls due to SWRID, a promising way to avoid super-knock is to remove radical species in the end gas near the walls. For instance, organizing pure air or EGR to be located at the periphery of the combustion chamber will help to avoid shock wave coupling with chemical kinetics near the wall. Or, organizing temporally-spatially distributed combustion, described as 1st stage combustion near walls, from burned gases without radicals such that the 2nd stage combustion occurs at the cylinder center.

Almost all existing knocking combustion studies focus on auto-ignition/detonation suppression, and the possibility of utilizing auto-ignition/detonation could be a future research direction. For instance, controllable HCCI is an example for utilizing lean mixture auto-ignition in internal combustion engines. Controlled detonation could be applied as for PDE/RDE (Pulse detonation engine or Rotary detonation engines) in the aerospace field. Some key scientific problems remain to be investigated, including detonation initiation. These problems include hotspot ignition, deflagration, sequential auto-ignition-detonation, detonation, and combustion mode transition in ignitable mixtures over wide temperature and pressure ranges.

In order to suppress/utilize detonation, it is required to decouple/couple shock waves and reaction fronts. This may be accomplished by changing the amplitude and propagation direction of the shock wave via mixture stratification and reactivity distributions, or wall interactions. Such research will not only be helpful to improve the performance of internal combustion engines, but also may benefit the development of advanced aerospace engines.

6.2.3. Engine knock control and super-knock solution

Simulation works are effective to guide knock research and engine development in order to achieve high efficiency and high load operation. Utilizing a reduced surrogate fuel mechanism, a practical flame model and an accurate heat transfer model in 3D-CFD to capture auto-ignition ahead of the flame, will be helpful to evaluate knock intensity and optimize the combustion system in a spark-ignition engine.

Using direct injection of a second fuel, such as ethanol/methanol or gasoline blends, is an effective means to avoid knock in spark-ignited engines. Further study may focus on the dynamics of alcohol vaporization effects on the charge temperature of the unburned mixture at high loads above 25 bar BMEP.

Pre-ignition and super-knock will still be major obstacles for engine development in the next decades. For pre-ignition and super-knock suppression, two aspects should be paid close attention to: One is the properties of the lubricant oil and fuel, including their cleanliness, additives, laminar flame thickness, ignition delay, etc. The other concerns the engine design and optimization, including piston ring land structure, spray pattern, injection strategies, flow motion, sealing system, and cooling system, etc. To develop an effective solution, more research is necessary to clarify the detailed mechanisms of pre-ignition and super-knock, especially the role that oil droplets, fuel and deposits play in this process. With the understanding that future engine oil formulations will have to meet performance and durability requirements, besides suppressing pre-ignition, a critical balance must be maintained for a holistic solution. The effect of fuel properties, including olefin, aromatic, ethanol, and methanol content on pre-ignition and super-knock is also a productive future research direction.

Finally, integration of cooled EGR, Atkinson/Miller cycles and multi-stage boost is also a potential solution to achieve above 27 bar BMEP.

 

[Garak]

It would seem to me that direct injection does matter, and the point remains that the traditional solutions do not work as well.

 

[avi1777]

what i dont get is there was small displacement 4 cyl turbo charged cars years and years ago with no lspi issues like my 2 wrx sti's both 2002models why only in recent years the lspi started to be a problem.and i think if it was a problem in a n.a engines the manual would say to use sn plus oil but in my2017 mazda cx 5 it dosnt.in fact u can use just about anything and its a very high compression gdi engine.

 

[avi1777]

and how an oil can help with ignition isuues?

 

[Gokhan]

Originally Posted by avi1777
what i dont get is there was small displacement 4 cyl turbo charged cars years and years ago with no lspi issues like my 2 wrx sti's both 2002models why only in recent years the lspi started to be a problem.and i think if it was a problem in a n.a engines the manual would say to use sn plus oil but in my2017 mazda cx 5 it dosnt.in fact u can use just about anything and its a very high compression gdi engine.

Originally Posted by avi1777
and how an oil can help with ignition isuues?

https://www.bobistheoilguy.com/foru...w-speed-preignition-lspi-and-super-knock

 

[PWMDMD]

Originally Posted by avi1777
it sounds diesel'ish not diesel to be exact and maybe yours sounded less its beacuse of the lower c ratio than the European models anyhow the web is full of mazda owners complaining on loud start ups and noise.


I agree....I drove a 2.5L Skyactiv for 60K and my nephew has it now at 100K and it runs great but ALWAYS sounded dieselish. It certainly sounded more diesel-like than the 3.5L Honda and Lexus engines I have now.

 

[PimTac]

The increased noise on startup of the SkyActiv engines is exhaust noise. The engines run very rich on a cold start and due to the bundle of snakes header design, it takes around ten seconds or so for the exhaust to settle in. Once it starts to warm up the exhaust scavenging effect kicks in.

The noise is not mechanical.

 

[DirectRejection]

Originally Posted by Gokhan
Originally Posted by avi1777
what i dont get is there was small displacement 4 cyl turbo charged cars years and years ago with no lspi issues like my 2 wrx sti's both 2002models why only in recent years the lspi started to be a problem.and i think if it was a problem in a n.a engines the manual would say to use sn plus oil but in my2017 mazda cx 5 it dosnt.in fact u can use just about anything and its a very high compression gdi engine.

Originally Posted by avi1777
and how an oil can help with ignition isuues?

https://www.bobistheoilguy.com/foru...w-speed-preignition-lspi-and-super-knock


Gokhan, I see what you did there !! Sorry for deviating, but I see you are now in the world of TGMO 0W16, with your Prius Prime vs the old Corolla.

Sidebar. Being that Castrol, the motor oil in this thread, is designed for film strength, with the Titatium, etc, would you ever consider Black Bottle EDGE 0W16 (I have seen it at Pep Boys) vs TGMO 0W16 ? I am thinking in terms of potential eventual problems with piston ring coking and valve stem seal wear.

I anticipate purchase of a Lexus UX 250H, myself, within a couple of weeks ! All the best with your Prius ! Please declare your oil pan drain plug gasket part number when appropriate !

I would also greatly appreciate going over with you in much detail oil selection vis a vis the different designs of your Prius engine 2ZR-FXE and the UX engine M20A-FXS.

 

[Gokhan]

Yep, three weeks ago coming from the grocery store only a block from home, the 1985 Corolla got destroyed by a hit-and-run LA driver who crossed the double yellow and almost collided head on with me. I almost avoided it but got hit at and above the left rear wheel, which made me lose control, spin left 90 degrees, and collide with a parked car head on. Unfortunately in LA drunk, drugged, uninsured, etc. drivers are very common and such accidents happen all the time. It's really Wild West here.

I got a really good deal on the 2020 Prius Prime XLE plug-in hybrid: below the invoice price - $1500 rebate - $6000 federal and California tax credit. Regarding how little Prius and Prius Prime depreciate, this is practically for free. I also get parking benefits at the university campus where I work and of course great mileage, especially on electricity. I got the antitheft protection and exterior/interior detailing for free as well because they were already on the car and I refused to pay the $1800 they were asking for them. The 2020 model that just arrived from Japan has added the third back seat with some other nice changes.

Note: These are the Sony Studios (previously MGM Studios) in the background.

With the 2020 model they have changed the oil recommendation to TGMO 0W-16 SN/RC or equivalent. The disclaimer "An oil with a higher viscosity (one with a higher value) may be better suited if the vehicle is operated at high speeds, or under extreme load conditions." is there as for any other Toyota. This car was made in August in Toyota City, Aichi, Japan, and the oil used is likely a Japanese brand -- it says 100% Japanese parts as typical with Toyotas made in Japan. Curiously, despite the viscosity changing from 0W-20 to 0W-16, the combined EPA MPG rating remains the same at 133 MPGe/54 MPG for electricity and gasoline, respectively.

They give two-year free maintenance; so, the first two oil changes will be done at the dealer. They actually made me buy a three-year extension but I will probably cancel it. I have a dislike for cartridge oil filters but very gladly they made a change and it uses the 90915-YZZF2 spin-on oil filter now instead of the cartridge oil filter as in the past. Oil drain plug and gasket are 90341-12012 and 90430-12031, respectively, per http://parts.toyota.com/.

Regarding oil brands I know Mobil 1 AFE 0W-16 is 100% PAO + AN. TGMO 0W-16 sold in US is made by ExxonMobil and it's 100% GTL-based. Mobil Super 0W-16 is also 100% GTL-based. I don't know anything about Castrol 0W-16 but as I said I am not in the market for buying oil until my free-maintenance period ends. Unfortunately I was only about 1000 miles away from doing a UOA on the PAO-and-AN-based Mobil 1 EP 0W-20 on the Corolla but now, that's history. I was getting around 29 - 30 MPG in mixed driving.

 

[PimTac]

Interesting how they placed the instrument panel up and to the center. That must take some getting used to from driving the Corolla.

Does this car come with a HUD?

 

[Gokhan]

Originally Posted by PimTac
Interesting how they placed the instrument panel up and to the center. That must take some getting used to from driving the Corolla.

Does this car come with a HUD?

No kidding, it's very complicated and there are a lot of things to learn. Fortunately I like technology.

Color head-up display (HUD) is only available on the Limited trim, which costs $4000 more than the XLE trim.