Ash content corrolations to Pre-Ignition
 

This information may be old, but does anyone have anything else to say about it?

I'm reading a paper on Engine oil lubrication for the Rotary Engine (RE), and there seems to be a strong correlation between ash content and pre-ignition events.

For instance an oil that contains <0.05 Sulphated ash % by weight took more than 40 (2.5 hrs run time = 1 cycle) cycles before the first pre-ignition event. For the second run it took 35, for each consecutive run there were no pre-ignition events. Compare that to oils that have relatively high ash contents (1.2, 0.9) which experienced their first pre-ignition event within 8 cycles.

On the market today, how many oils are there that have a lower Ash content similar to the <0.05? Do synthetic oils use base stock with that low of an ash content? I tried looking at Royal Purples website, but they offer no insight on the ash content of their product.

i can tell you without a doubt that knock goes up when plugs start to get fouled even a little bit which in turn causes them to foul and even cake up even faster.

So how do we tell the ash content of oils? I tried looking up the API ratings, and they only dictate ash content on diesel oils.

good question do they not put that info on motorcycle or 2-stroke oil?

I'll check. I'm still looking, but I found an engine oil that does list it's ash content from the ASTM D 874 to be 0.88

http://www.nulon.com.au/products.php...day_Engine_Oil

That's rather high, and not good engine oil for our motors... so beware.

http://www.api.org/certifications/en..._Oil_Guide.pdf

Is a good guide, but only references Ash in the CJ-4 rating.

Still looking:
http://www.purvisbros.com/supduty.htm
Pennzoil Supreme Fleet Oil has 1.4%

The most informative I could find so far.

I've been picking the brains of my local car club about this and it seems like we'd want to run diesel oil (CJ-4 rating). This is what I got from there

Very interesting stuff right there!

completely procrastinating my studying for Operational methods test tomorrow:
These are from Bob Is The Oil Guy website/forum. All are Virgin oil analysis'.
http://www.butler-machinery.com/reso...Oils/New_1.jpg
http://www.butler-machinery.com/reso...Oils/New_2.jpg
http://www.butler-machinery.com/reso...Oils/New_3.jpg
http://www.butler-machinery.com/reso...Oils/New_4.jpg
http://www.butler-machinery.com/reso...Oils/New_5.jpg
http://www.butler-machinery.com/reso...Oils/New_6.jpg
http://www.butler-machinery.com/reso...Oils/New_7.jpg

Although slightly off topic those who are running Two Stroke oil (aka, premix). I'm curious what you think about this:

http://i123.photobucket.com/albums/o...rannyFluid.jpg

If you notice, the apex wear is about 19.6 Micrometers/hour of operation which is roughly 17.4 more micrometers/hour of wear when compared to conventional oils. Is it really beneficial to go to Premix with these statistics?

tell me if i am wrong, but wasn't that being compared to ATF and found to have half the wear?

If I interpreted the data correctly, 19.6 um/ 2.5 hours with only 1.5 mm allowable wear (8.0 mm stock, 6.5 mm allowed) gives about 200 hours (12,000 miles) before wear becomes a problem on a premixed rotary (which I really don't believe). Granted, this is full-throttle useage, but that number seems out there a little.

I have seen 150,000 mile rotaries with 6.9 mm of apex seal left.

I am not sure that these are 2.5 hour cycles.

I'll have to double check what the cycle times were for the endurance run. But yes, that was comparing ATF to Two Stroke.

Here's the procedure for the endurance test:
A succession of mixed low-speed/low-output (2500 rev/
min and 20 hp) and high-speed/high-output (6000 rev/
min and 100 hp) sequences followed by idling, for 96 h.
Each individual sequence lasts 6 h.


Which mean's it's 19.6/96h = .204167 micrometers/hour compared to the 13.5/96h = .140625 micrometers/hour, which is significantly less than the two stroke. Redoing your math we have:
1500/.204167=7346.94 hours assuming 60 miles/hour of operation speed gives us a little over 440,816 miles.
1500/.140625=10666.767 hours of operation assuming 60 mph of operation gives us a little over 640,006 miles

Using standard oil instead of two stroke has the theoretical ability to last 1/3 longer than two stroke.

I think I am confused. I read 38 um / cycle wear for ATF and 19.6 um / cycle wear for two-cycle oil. Is the 13.5 published somewhere else that I can't immediately see?

The 96 hour cycle makes a lot more sense, but I am still confused about the above numbers.

Also, this test was likely done with the same quantity of each oil injected through the stock oil injection system. This data does not prove that additional two-cycle oil increases seal wear.

Yes, the 13.5 is published in the sae paper, but I didn't copy/paste a picture of the chart.
Volumes are measured as you can see in the previous posted image--but not constant. The volumes differ from one to the other, but may be based upon viscosity and other possibilities. However, since both instances of the engine were run per cycle (96 hours), and greater wear was indicated with two stroke it is only plausible that running two stroke for lubricating the apex seals is not as efficient when it comes to lubrication of them. That is not to say that it's not beneficial to run two stroke for the lubrication of the apex seals since ash content would be reduced to nill, and would burn cleaner than regular oil.

Vex, the NSU paper spoke of their "prime candidate" oil having half the wear, and the "Typical Marine Cylinder Lubricant" in fig. 16 showed extremly low wear data. Do you have any idea which oils these are?

From your analysis of the "CAT New Oil" charts above which oil would you think is best for rotary engines?

Thanks for the information backup to your original questions. You presented this well.

Barry

To which paper are you referring. I have two NSU lubrication papers (2nd and 3rd). Neither paper references a Fig16, however the 3rd NSU paper has a section 16... As for the Cat VOA I haven't looked too much into those yet. I'll look at them now, but I by no means, am an expert when it comes to figuring out which oils will be perfect for the rotary engine.

Disclaimer: I'm still refining this list and doing research as best I can to give the most accurate representation of the data I can. Please check this post often (or at least until the disclaimer disappears as I'm constantly refining the oils listed).
Ash content is usually caused by impurities in the base oil. Which I believe is caused by Calcium being the biggest indicator. Looking solely at that these are the oils that contain calcium in <500 ppm.

Castrol 0w-30
Cenex AGME 4EP
Cenex AGME 7EP
Cenex Indol ISO 68
Cenex ISO 46
Cenex Mercon/Dexcon ATF
Cenex Turbine XL ISO 100
Cenex Turbine XL ISO 320
Chevron 80w-90
Exxon 60wt
Exxon 60wt
Hyde Dexron
Royal Purple 75w-90
Shell Omala 320
Unspec Unspec

Now you'll notice that a lot of the previously mentioned oils are not really suitable for use in an engine (gear oil, increased wear with ATF/dexron belnds, etc). So getting rid of those what we have left is:

Castrol 0w-30
Cenex Indol ISO 68(Really light oil it looks like)
Cenex ISO 46 (Really light oil it looks like)
Unspec Unspec (4/26/05)
Cenex Turbine XL ISO 100 (may be too thick for use; viscosity rating is the same as a 20w oil)
Turbine XL ISO 320 (may be too thick for use;viscosity rating is the same as a 20w oil)

Now looking at the additive package: High in zinc, low to medium in phosphorus, we have the following arranged low to high by such [Phosphorus|Zinc]

Unspec Unspec (4/26/05) [2|38]
Castrol 0w-30 [284|2]
Cenex Indol ISO 68 [383|517]
Cenex ISO 46 [963|1163]

Conclusion: Although a majority of the Oils listed can be used in a rotary engine, I would suggest using Cenex Indol ISO 68 based on the information I could see from the CAT VOAs. This is basing it off the findings of the NSU/SAE papers previously referenced. If the PPM on the Phosphorus is not high enough for your tastes Cenex ISO 46 will work slightly better. Please be aware though that the higher the Phosphorus the more likely foaming will occur. Please take steps to keep this from happening if and where possible.

http://i123.photobucket.com/albums/o...orrelation.jpg

So far I've only been able to find this product from Cenex that is even close to what we're looking for. Further investigation is needed as previously attested two stroke oil will wear parts faster than conventional oil.

http://www.realtruck.com/shared/pdf/...ineextreme.pdf
http://www.cenex.com/portal/server.p...ed=true&mode=2

Further break down of the previous Oils listed:
Cenex Indol ISO 68: https://www.cenex.com/portal/server....dol_010305.pdf
Cenex ISO 46: https://www.cenex.com/portal/server....nex_122104.pdf
Cenex Turbine XL ISO 100: https://www.cenex.com/portal/server....lXL_010305.pdf
Cenex Turbine XL ISO 320: https://www.cenex.com/portal/server....lXL_010305.pdf

So if i'm interpreting things correctly, does this mean that using ATF in an oil injection system is better for apex seal lubrication over 2 stroke? Then what would be the comparison to engine oil? and at what point does the ash content come into play? Doesn't it just trade off one problem for another?

No, Two stroke out performs ATF with slowing Apex seal wearSee later posts regarding thatPre-Ignition events. The lower the ash content the less likely a pre-ignition event occurs Not really. We're looking for low ash content which is reflective in the base oil being excellently refined. We're also looking for an additive package that still cleans and protects. The protection comes from the oil and additives, not from the ash and impurities.

VEX,

Third Paper
LUBRICANT DEVELOPMENT FOR THE
WANKEL-TYPE ROTARY ENGINE
page 4, top and bottom, Figs. 16 & 17.
their "prime candidate" oil Fig 17, has half the wear, and the "Typical Marine Cylinder Lubricant" in fig. 16 also shows extremely low wear data.

Unfortunately the CAT VOR info doesn't include sulfur in their testing!

Which Castrol 0w-30 are you referencing? There are a few listed. It would be great to find an oil that was stocked locally in stores.

Barry

I see. I don't know why I didn't see that before. From my reading of it, the oil to which they are referring appears to be "...the oil formulation which satisfies the preignition test (explained later) and at the same time gives
the best cold-wear performance contains magnesium at a total sulphated-ash level of 0.4 per cent by weight." My best guess for that would be an oil based off of magnesium rather than calcium. The calcium and magnesium when burned produce a portion of the sulphated ash (see above figure for more understanding regarding that; basically, the more calcium the higher the ash content--that is my understanding at least). So we'd need to find an oil that has a magnesium 400ppm rating. That should give similar if not the same results for which they were relating.

As for the Castrol 0w-30, that is all the distinguishing markings of the oil they tested. There's no further classification of it. On the CAT charts look for Castrol [Blank] 0w-30. That is the one I'm referencing. You can verify that by looking at the calcium readings.

Vex, I read a few more articles about preignition on high performance outboard and air cooled aircraft engines. They only promote Ashless Oils.

It seems like Valvoline makes an ashless oil that may be a good rotary oil.

VR1 Racing Formula SAE 20W-50 (Turbo Approved) Motor Oil (other weights also).

Key features Valvoline VV211
High public presentation and shelter in spite of today's engines that go at high-pitched RPM
New ashless anti-wear additives combined by the side of ZDDP bring home the bacon most remote endure shelter
Enhanced anti-foam scheme helps secure the instrument regular for the time of uttermost emphasise
Enhanced additives preserve fronting high-temperature deposits with regard to a dry cleaner weapon
Friction modifiers facilitate gain h.p. yield

Barry

Very interesting thread.

Any speculation as to why oil ash content causes higher preignition? Is it because of the ash in the exhaust->intake carry-over volume due to the burning oil in the expansion/exhuast strokes?


Preignition within 8 cycles??!! I doubt many people have paid that much attention to oil ash content in the past -- how can there not be more blown motors because of this?

Sweet! I'm game for testing it out. Do we have a distributor (online or IRL)?

8 cycles on a single rotor test bed. Just because you have a pre-ignition event does not mean you'd have a catastrophic pre-ignition event.

As for speculation on why the ash causes pre-ignition events it's nothing more than a few ideas being passed around. As it stands right now the Pre-ignition is a direct result of ash because of carbon build up on the combustion surfaces. The carbon build up carries over heat causing the pre-ignition event where the gas reaches its flash point with contact to the surface. But that's just a theory.

Vex and Joff,

In the NSU paper linked above, the engineers were finding engines being destroyed after high speed runs on the Autobahn. Their conclusion was preignition for metal ash deposits on the rotors.

The good news on the Valvoline VR1 is that I found it a O'Reilly's so it may be a other automotive stores also. They only had it in 50W and 20W50. It comes in 10W30 and 10W40 also.

Barry

It's been a while since I've looked at the NSU papers, do you have a page to the conclusion that declares the ash deposits on the rotors as being the cause? I was thinking it would have been a combined effect of the plugs and combustion surface.
Is it classified as fully synthetic, or is it a highly refined conventional?

Yeah, I missed the part where 1 cycle = 2.5 hours and thought it was meant 8 rotations of the rotor which sounded absurd.

This theory could be tested by replacing oil with ashless oil and seeing if a high preignition rate continued. I presume carbon build-up accumulated would not instantly vanish?

That presumption would be correct (however the carbon instantly vanishing is not necessarily true. It will still need to be burned off, or dieseled to remove the built up carbon, which in and of itself may cause issues with the cars setup). NSU papers did multiple tests. The problem comes with the oil not containing ash, but impurities that produce ash when burned. Hence the high PPM of Calcium causing more sulphated ash, and the respected correlations. VOA and UOA are helpful in narrowing it down to oils that would work stellar in our engines. The problem comes in that a majority of "high end" oils contain low calcium numbers, but those numbers are still too high for our engines (remember the lower the sulphated ash the better; <500ppm of Calcium). Running a pure base, or synthetic that has <<<500ppm of Calcium is the better.

On that note; I did not find VR1 oils at Pepboys in Alexandria, VA. Next time I go to an autoparts store I'll check for it.

All interesting reading...thanks to VEX and all contributors. My head's spinning since I'm just a dumb goverment employee.

My question is that in the F I models, how well or poor the oil burns is only half the equation. How it performs in the high heat and extreme rpm turbo enviroment is the other. For that, it seems synthetic is superior. Is there something to look for in the analysis/content charts that would help a chemistry challenged lay-person balance those needs?

One would think. The trouble with our cars however is that even naturally aspirated we need rather good oil. There should be no difference in the oil you use from a turbo car from an NA car.

You're still looking for the base materials to be extremely low. IE: Calcium. The lower the ppm (parts per million) the better, while additives like zinc, and some detergents will prove beneficial so long as there's not too much. Especially if the car is turbo, which would lead to a fair amount of foaming. I'm trying to find some VR1 oil that was mentioned, but so far my searching has returned nill.

Found VR1 at Autozone and O'Rielly's in 20w50 and straight 50w. Wanted 10w30. It is not a synthetic oil.
Barry

My local ADVANCE AUTO only carries it in 20w-50 as well.

I don't understand. Aren't synthetic's generally more resistant to shear and coking? And isn't this a concern with the extreme rpm and heat of turbos?

The benefit of synthetic over conventional is the base they use. On the previous pages compare what is known as synthetic to good grades of conventional such as VR1. You could have a "good" synthetic with worse qualities for our engines than a top rated conventional. Drawing generalities across the board will cause trouble for people.

If you however compare VR1 to an oil like royal purple would you see a difference, I don't know. I don't know the UOA or the VOA's of the two.

Advance carries 20w-50 (but they never seem to be in stock) and 50... I ended up doing royal purple 10w-30 (though I would really like to run 20w-50 when it comes around) for the time being.

I've also noticed a price difference between the two. About a full dollar or more just at advance....

ZR1 Synthetic stats: http://www.valvoline.com/pdf/vr1_synthetic.pdf
ZR1 Conventional Stats: http://www.valvoline.com/pdf/vr1_racing.pdf
ZR1 Racing (non-street legal): http://www.valvoline.com/pdf/specialty_racing.pdf

Whys one not street legal?

According to mazpower; it deals with the anti-wear package and how much ZDDP is in the oil. Too much and it will clog cats.

Valvoline
Conventional: http://www.valvoline.com/pdf/premium_conventional.pdf
(sulphated ash:0.8)

Conventional - Next Gen: http://www.valvoline.com/pdf/nextgen_conventional.pdf
(sulphated ash: 0.8)

MaxLife: http://www.valvoline.com/pdf/maxlife.pdf
(sulphated ash: 0.93)

MaxLife Synthetic: http://www.valvoline.com/pdf/maxlife_full_synthetic.pdf
(sulphated ash: 0.93)

MaxLife NextGen: http://www.valvoline.com/pdf/nextgen_maxlife.pdf
(sulphated ash: 0.93)

Durablend Synthetic: http://www.valvoline.com/pdf/durablend.pdf
(sulphated ash: 0.99)

Synpower: http://www.valvoline.com/pdf/synpower.pdf
(sulphated ash: 0.93)

Mobile 1
Extended performance: http://www.mobil.com/USA-English/Lub...rformance.aspx
(sulphated ash: 0.8)

Advanced Fuel Economy: http://www.mobil.com/USA-English/Lub...l_Economy.aspx
(sulphated ash: 0.8)

Mobil 1 0w-40: http://www.mobil.com/USA-English/Lub...l_1_0W-40.aspx
(sulphated ash: 1.3)

Mobil 1 5w-20: http://www.mobil.com/USA-English/Lub...l_1_5W-20.aspx
(sulphated ash: .85)

Mobil 1 5w-30: http://www.mobil.com/USA-English/Lub...il1_5W-30.aspx
(sulphated ash: .8)

Mobile 1 10w-30: http://www.mobil.com/USA-English/Lub..._1_10W-30.aspx
(sulphated ash: .8)

Mobile 1 15w-50: http://www.mobil.com/USA-English/Lub...l1_15W-50.aspx
(sulphated ash: 1.21)

More to come.

Royal Purple... can't find anything from their site.
HPS: http://www.bobistheoilguy.com/forums...49#Post2578549