Adding two stroke oil in gas?

[johnl]

A lot of our setups use fuel to supress detonation and to cool the top end. This can acccelerate the advent of cylinder wall taper by way of the fuel "washing" the oil off the cylinder walls, especially near the top of the stroke. Also, with good stem seals, valve guides can wear out before cylinder walls & rings.

So, why not add a little two stroke oil to our gasoline?

If OK, how much?

What's the effect on octane? Compatible with ethanol blend?

[Directconnection]

Oil will decrease your "detonation suppression" as I see it.

Also, 2 strokes don't get their fuel from the top end... it enters mid-bore.

It might help.... but I am not feeling so sure of that :nod:

[turbovanman²]

I don't think it will help, all it will do is carbon up the engine, make it more detonation prone and raise the compression over time thus making it even more detonation prone.

Use a fuel treatment designed to lubricate the top end.

[T-Bohn]

I think, not so good...by adding 2 stroke oil you will be taking away fuel which would not be a good thing.

Stay away from bean oils. go full synthetic "premix" not injector oil. 50:1 is often used in 2 strokes so go higher than that. 75:1 100:1 but at those levels what does it really do??

[Mopar318]

Your going to lower the octane rating of the fuel therefor lowering the flash point temperature of the fuel (AKA pre-ignition)

My volvo 850 turbo had leaky valve seals, and now there is a hole in one of the valves.:(

Oil in fuel is bad.

[johnl]

Steve, most two strokes today are no longer pre-mix, of course; they direct inject their oil in several places - directly into the mains and even the big end; the wrist pin and cylinder walls get the atomized fuel/oil mix that results from oil injected at the carb or throttle body.

Yes, less detonation suppression, but how much?

Simon, as for carbon buildup, the new synthetic TC4 2 stroke oil is very clean burning, far less residue than back in the day.

Two strokes that run on premix need at least 100:1 and that ratio is mainly for the rollers and balls of their mains, rods and wrist pins; I suspect that they don't need as much oil for the pistons/rings/cylinder walls as they do for the bearings. So, I'm thinking that a light mix might burn clean and help prevent wear of our fuel soaked cylinder bores and valve guides.

There really is no oil that is better engineered for both lubrication and combustion than TC4.

[T-Bohn]

I have been thinking about how much oil, just to get a sense of it.

12 gallon tank @ 128 oz. per gallon = 1536

100 to 1 ratio would be 15.36 oz.

Is my math wrong??? This seems like a real lot of oil!!

[Johnny]

What about Rislone instead?

[RoadWarrior222]

ONLY one kind. TCW3 outboard oil, it's ashless and O2 and cat safe. The most you want in is 2oz per tankfull. It is actually effective for lubricity at 1000s to 1 ratios, designed that way so if you run your $5000 boat motor and forget to add it one time, it should live on the residue in the tank.... even though the spec might be 200:1

Anyway, you can pick up about 2 or 3% on fuel mileage from it, I was using it to keep fuel pumps alive while playing with various solvents and alcohols as additives.

Would very very marginally affect octane at 2oz/tankfull type concentration.

---------- Post added at 09:52 PM ---------- Previous post was at 09:51 PM ----------


What about Rislone instead?that stuff is mostly solvents or paraffin/kerosene type fractions...

---------- Post added at 09:55 PM ---------- Previous post was at 09:52 PM ----------

Oh johnl must be talking about TCW4, which is next gen TCW3

[johnl]

Thanks for the correction, RW222.
I'm just confused, TCW3 is what I meant.

So, you agree? Can't hurt and might help?
Somewhere, with reference to outboards, I read that it also tends to stabilize ethanol blended gas? Is that true?

[RoadWarrior222]

Probably does, it helps stuff mix together (and stay mixed) including itself.

[black86glhs]

Use it during the wet season to control mosquitos.:thumb:

[RoadWarrior222]

I don't think it will help, all it will do is carbon up the engine, make it more detonation prone and raise the compression over time thus making it even more detonation prone.While I might suspect that yard tool 2 stroke mix at 20:1 ish would tend to do that, the outboard stuff is high detergent and ashless. Also de-carb additives that work out at several hundred to one mixes in a tankful are typically kerosene or mineral spirits, which are "oilier" hydrocarbons than gas, not sure actually how they're meant to work in the chamber, but know that you can dissolve and mobilise carbon with them if you're cleaning up a motor. It's probably just that carbon is hard to light off when it's plastered against the wall, and anything that picks it up helps it burn.

[Reaper1]

If you are using enough fuel to taper cyclinders in these engines...you are using WAY too much fuel!!!

Stay away from using 2-stroke oils in the fuel regularly. I don't see it being an issue every once in a while, but I still say...WHY!? These engines are designed to work as 4-strokes. With correct tune and mechanical set-up, and the internal seals functioning as designed...the issue you are describing should be non-existant.

How many have DOCUMENTED significant cylinder tapering in these engines?

[contraption22]

I think you are spending time coming up with a solution to a problem that doesn't exist.

[johnl]

Taper, in highly boosted engines does not exist?

Who's running stoichiometric at 20 pounds and more?
At 10 or 11:1, that's a lot of fuel and it doesn't compromise cylinder wall lubrication?

[contraption22]

For how much of your engine's total running time are you seeing those A/F ratios? How many hours of those conditions between oil changes?

[turbovanman²]

For how much of your engine's total running time are you seeing those A/F ratios? How many hours of those conditions between oil changes?

Exactly. If your worried about it, then get a Metro or Honda, :lol:

Seriously, run synthetic oil, add a fuel additive to lube the top end, run a proper tune and problem solved.

[contraption22]

I could see the concern if we see alot of Chrysler turbo engines smoking like old Mitsu 3.0's and have low compression issues, but we don't. More often than not, when I took apart a half-assed maintained 2.2/2.5, I saw good bores.

[RoadWarrior222]

That's not the reason why 3.0s smoke though... just pointing out.

Couple of BITOG guys seem to like TC-W3 better than top end lube....
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&topic=90452

BTW, pulled a couple of MSDSes for TC-W3, I'm noticing something.. the "oil company" TC-W3s have just high refined oils and kerosene type fractions, the "outboard company" TC-W3s have acid neutralisers, which might be a very good idea with ethanolated gas...
https://docs.google.com/viewer?a=v&q=cache:vdEQzKxP_OUJ:wwwarchive.mercurymarine.com/uploads/1652/2086/090-0968K-16pt._2doc.pdf+&hl=en&gl=ca&pid=bl&srcid=ADGEESjFJiXtG8DVUox92HqD8e8XPMeOrG-IyRcuU0djfHbw9DpEaG5sfV3Xl55ece5jzwetrFi6rStmEIOSy cP2PZDPGXB_7LzMiBU3MbqRGekovDInbfmV9SbE3Ow-_OWcCcok4u7s&sig=AHIEtbQUM2S_ThdZJhG9wVg2zWQQ-VvyNw
https://docs.google.com/viewer?a=v&q=cache:UZW5zks7SioJ:datasheets.bp.com/ussds/amersdsf.nsf/0/51297FA7BAD6E2B986257307004F83B6/%24file/014229US-Lubes%2520Americas-BP%2520%28Wayne,%2520NJ%2520US%29.pdf+&hl=en&gl=ca&pid=bl&srcid=ADGEESgTcwuH84quOQuInwRSPBFBYyiZPTqk0GRPxzyp 5dH_G_oJDO8UrdLFO-bCuIIWPJ6kRbPkk-JKERfxqYGrmam28mcaraCQGs1Ws4S-Zy-v-wQscspc5-zV1xBDw_E9qTAazSkP&sig=AHIEtbQM-KW5uGOFoUxmQEveCHM6hjS3cg

Plus there's the "proprietary" part of the outboard company stuff, which I have a suspicion might be burn catalysers or something...

Anyway, what I had been using was Evinrude stuff, I picked up a stash of at somebody's yard sale... I haven't used it heavily in the Escort, due to MPG yo-yoing all over from maintenance and tune issues, and attempting to investigate an in-port catalyst effect, but I used it steadily in the Voyager... was seeing 26 and 27 mpg with the magic recipe of 1oz TC-W3, 2oz IPA, 8oz methanol in E-10 gas... I have used it too irregularly to get stable mpg figures off since.

[contraption22]

That's not the reason why 3.0s smoke though... just pointing out.


I know... I was just trying to think of something that smokes alot and those came to mind.

[Reaper1]

Taper, in highly boosted engines does not exist?

Who's running stoichiometric at 20 pounds and more?
At 10 or 11:1, that's a lot of fuel and it doesn't compromise cylinder wall lubrication?

Taper can certainly exist, however I've not heard of it being a major concern with our engines. We don't run high-tension rings (usually). The 2.5 has worse side loading than the 2.2, but the pistons take the brunt of that.

Taper was something that was a major issue in older engines. Simply put, the alloys they had back then weren't as tough as the ones we have now (or had when these engines were made). Our blocks don't suffer from that sort of wear, typically.

As far as running soich under boost...nobody that *I* know of does that, and there are only a small handful of private individuals that would even attempt that sort of lean burning under that sort of load. Keep in mind that the fuel, under those loads, also acts as a heat sync. It helps cool the parts inside the chamber. Just because there is more fuel than what an ideal chemical mixture for optimal burn is present doesn't automatically mean you are getting fuel wash. Those that are running high levels of meth injection might want to look into this a bit more, since THAT has a perpecity to wash the walls of lubricant (most alky only cars DO run some sort of lube in the fuel just because of this), but even still, I don't know of anyone having this issue with a propper tune and using good, synthetic oil.

To really know if you are having fuel wash issues, just send your oil in for sampling. That will tell you everything you need to know about what is chemically going on in your engine. You can then decipher if there is too much fuel in the cyclinders, contaminating the oil. It should also show high amounts of iron due to the rings scraping the cylinder walls. Heck, run a bore scope down into the sparkplug hole and take a look at the walls! Is it highly glazed? What does the piston/wall clearance look like? Do a leakdown test with the pistons in different positions in the bore.

All of those things can indicate whether this is an issue to be worried about or not. I'm not bashing you, I'm giving you suggestions to investigate the problem before you go adding stuff to your fuel that simply isn't needed. RW222 is a unique case in that he is introducing aditives that CAN wash the cylinders, so the extra lube probably didn't hurt there as those chemicals also raise the octane of the fuel and probably offset the degridation caused by the oil.

[johnl]

Thanks to all for the thoughtful replies. I want, as they say, "critical thought." Thanks again.

Yes, of course, my questions about taper and ratio were rhetorical; we all get taper and we all run richer than stoichiometric - to cool the parts, and while taper growth may not be a perceived problem, there are an awful lot of 20 over engines out there and most of those, but for taper, could have been honed. And, yes, with a proper tune we are only rich in boost but isn't that exactly the moment when we want to protect the rings/bores? I mean, that's the dynamic moment when ring pressure against the bore is greatest. Heck, there might be some power to be gained by reducing that point/moment of greatest ring friction.

So, why not consider the possiblity that we could head off a possible cause of taper growth with some kind of top end lubricant added to our admittedly rich fuel ratios?

Great links RW222, interesting how the outboard packages are different.

[RoadWarrior222]

Heck, there might be some power to be gained by reducing that point/moment of greatest ring friction. Well there's a bit of a dichotomy there, in that the slippiest rings are moly faced, (soft) but the rings that take the most pounding are chrome faced (hard). The soft ones hold out, while CC temps are under control, but the chrome survive mishaps better... I guess it all comes down to how much to trust your tune and components i.e. injectors, fuel pumps etc not crapping out, not getting a tank of crappy gas etc.

[johnl]

Following your link, I found an interesting discussion on the The Bob the Oil Guy site about the two types of 2 cycle oil - air cooled vs water cooled, the former anticipates higher ring land temperatures, the latter lower ring land temperatures. The break point for the two oil packages is 300*f.

TCW-3 is the marine engine manufacturers' specification and it assumes lower speed two strokes, trolling, zero problems with cooling but sparkplug fouling, and that's why they don't need, and can get away with, zero additives that create ash.

The motorcycle and snowmobile manufacturers' speciification (JASO FD) assumes higher engine speeds, higher temperatures and less problems with sparkplug fouling because of constant variation in engine speeds, and that's why they can use, and need, the magnesium/calcium/zinc compounds that provide lubricity when heat overcomes the oil.

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2714912&Searchpage=1&Main=181107&Words=tcw3&Search=true#Post2714912

If you are seeing burnt oil on the bottom of you pistons, then your ring lands may be seeing more than 300* . . . . . and that would suggest the use of the JASO FD type oil but then the O2 and Cat will likely suffer from the additives.

There are dual purpose TCW-3 oils that may get their higher temperature capability from superior synthetic stock instead of from ash creating additives.

[zin]

Oil typically kills the octane and has a net negative effect when under heavy loads... The most spectacular destruction I've seen to pistons was from those cases where oil control was lost and the engine was still run, stuff's like napalm in those cases...

The stuff RW22 is referring to may not be so bad, as there is oil that isn't so destructive, typically used in superchargers that use a fixed oil reservoir. They it so that if the bearing seal goes, it doesn't detonate the engine into oblivion due to the oil being ingested...

Mike

[Reaper1]

I don't know what kind of experience the people that might have commented on marine engines turning low rpm, but with 11 years experience in that industry I can tell you that those engines are run either all or nothing 95% of the time. Redlines on those engines are anywhere from 5500-7000rpm. The extremely high performance engines can have redlines in the 8-10k range, and if built even higher. They *can* foul plugs at lower rpm, but usually that's more of the plugs being worn out, too much oil being mixed, the carbs not being adjusted correctly, ect....NOT the oil! TCW3 is some of the cleanest burning 2-stroke oil you will find simply because, like catalytic converters, it helps reduce the direct impact on the environment. 2-stroke marine engines are some of the harshest polluters (or were) because of how direct they indroduced the pollutants. I'm not saying there isn't better out there (I use Klotz in my HPI 5T r/c truck), just stating some facts that seem to be misconstrued.

[johnl]

Yes, they do run either at idle or WOT. And, they have a lake or an ocean as coolant so operating temps can be held low.

And yes, trolling and harbor putt putts used to foul plugs before TCW-3.


How much more detonation would, say a 500:1 mix of gasoline to TCW-3, cause? By the same token, how much lubrication benefit would such a trifling mix add?

[RoadWarrior222]

Well even if it was zero octane it would make just about 2 points difference 91 octane would become 90.8 octane.. so how safe from detonation are you? If you've got to pick and choose whose 91 octane you use, then you've got it a bit marginal anyway, but if you can use 89 octane in cool weather you're probably okay.

[BIGBRUDDA]

More importantly John, you'll need to play a RRIIIIIINNNNGGGG DIINNGG DING tape at full volume. Every where ya go.:eyebrows:

[RoadWarrior222]

Well that would be really annoying (http://www.youtube.com/watch?v=oXQkMGffOBo), could even drive you insane (http://www.savageresearch.com/humor/insanityTest.html), make you think you were Rubens Baricello or something.

[turbovanman²]

Yes, they do run either at idle or WOT. And, they have a lake or an ocean as coolant so operating temps can be held low.

And yes, trolling and harbor putt putts used to foul plugs before TCW-3.


How much more detonation would, say a 500:1 mix of gasoline to TCW-3, cause? By the same token, how much lubrication benefit would such a trifling mix add?

Now I could be wrong, I have been once before, :D but most or all 2 stroke boat engines don't have forced induction, so they don't have to worry so much about detonation.

[RoadWarrior222]

They do sorta, some are loop charged, but it's not a whole lot over atmosphere.

[Reaper1]

I've seen a LOT of 2-stroke marine engines made into junk because of detonation. I think it mainly has to do with crappy gas or carbs that are gummed up not giving the correct mixture in certain cylinders. When they let go, they make a MESS!! I've seen some metal parts bent and contorted ways that just don't seem possible! LOL

[wallace]

Late to the discussion but don't the higher end 2 stroke oils actually contain some form of octane boost? Klotz (I think that's the one) uses Benzene in its mix...it the exhaust smells like puke to me.

[RoadWarrior222]

BTW, put some in the Escort this morning, it has been sounding a little on the rough side and due for a clean out, but also the fuel pump has started to sound weak when priming, so it got 6oz IPA for cleaning and 1oz Evinrude TC-W3 for the pump (And the help of whatever detergents might be in it)

[johnl]

Late to the discussion but don't the higher end 2 stroke oils actually contain some form of octane boost? Klotz (I think that's the one) uses Benzene in its mix...it the exhaust smells like puke to me.

Wallace -
Good point. But, then again, Klotz is assuming a far richer ratio of oil to gas then we're considering here.


RW222 -
Let us know if your pump quiets down; IIRC you reported improved mileage already, as I see a lot of others also have - at the Bobtheoilguy site and elsewhere, along with claims of smoother running and easier/quicker spin starting.

---------- Post added at 05:59 PM ---------- Previous post was at 05:55 PM ----------


They do sorta, some are loop charged, but it's not a whole lot over atmosphere.

Yeah, and that's what an expansion chamber does too - sucks the intake in such that with inertia and velocity greater than atmospheric is achieved.

[johnl]

http://www.rx7club.com/single-turbo-rx-7s-23/castor-927-vs-idemitsu-premix-998040/

I asked an old two stroke racer friend about the extent of pre-mix' propensity to detonate and he said he doesn't know but that he runs pre-mix in his twin turbo Mazda rotary.

They run something called Idemitsu which is specific for rotary engines but it is said to separate out in E85 so if that is a problem then they run Maxima Castor 927 which is a two stroke oil that is compatible with E85 - and, I imagine, therefore with alky injection.

Maxima's site -
http://www.maximausa.com/shopping/index.php?main_page=product_info&products_id=13

Maxima's Material Safety Data Sheet - secret sauce.
http://www.maximausa.com/msds/2stroke/Castor 927.pdf

Indemitsu -
http://www.idemitsu-usa.com/h/38/premix.htm

Indemitsu's Spec Sheet
http://www.ilacorp.com/images/web_premix.pdf

Indemitsu's MSDS, FWIW
http://www.ilacorp.com/images/2828-042a.pdf

[RoadWarrior222]

So on that tank, mpg no different, but starts first turn or two again, and the pump went to a smooth bzzt at prime again, instead of bleeargh... and it's lost the rough edge while running now.

[Reaper1]

http://www.rx7club.com/single-turbo-rx-7s-23/castor-927-vs-idemitsu-premix-998040/

I asked an old two stroke racer friend about the extent of pre-mix' propensity to detonate and he said he doesn't know but that he runs pre-mix in his twin turbo Mazda rotary.

They run something called Idemitsu which is specific for rotary engines but it is said to separate out in E85 so if that is a problem then they run Maxima Castor 927 which is a two stroke oil that is compatible with E85 - and, I imagine, therefore with alky injection.

Maxima's site -
http://www.maximausa.com/shopping/index.php?main_page=product_info&products_id=13

Maxima's Material Safety Data Sheet - secret sauce.
http://www.maximausa.com/msds/2stroke/Castor 927.pdf

Indemitsu -
http://www.idemitsu-usa.com/h/38/premix.htm

Indemitsu's Spec Sheet
http://www.ilacorp.com/images/web_premix.pdf

Indemitsu's MSDS, FWIW
http://www.ilacorp.com/images/2828-042a.pdf

Ro-tard-ries use oil injection from the factory. This helps with the apex seals. The reason the racers use the pre-mix is to help even more. ALL ro-tard-ries use oil. They are a lot like a 2-stroke in many regards, so it works fine for them.

[zin]

Rotaries also don't run much compression and tend to run cool and rich.

When I was at Chaffey, we had a rotary racecar and not only did we not need to run race gas, but it was fine on 87!

We did have to build the "header" out of roll-bar material after the standard stainless tube burned through at the turn coming off the exhaust port though...

Mike

[Reaper1]

Rotaries also don't run much compression and tend to run cool and rich.

When I was at Chaffey, we had a rotary racecar and not only did we not need to run race gas, but it was fine on 87!

We did have to build the "header" out of roll-bar material after the standard stainless tube burned through at the turn coming off the exhaust port though...

Mike

LMAO!! If there was ever a perfect example of how inefficient a ro-tard-rie is...that is the one! The EGT's are usually through the roof on those things! How does this relate to being inefficient you ask? Well, if the EGT's are that hot, that means some combustion is still happening when the exhaust port is exposed, so it is just throwing away power and energy! (part of the reason they can spool huge turbos) It also increases emissions. There is really nothing that can be done about it either. (I'm not saying something can't be done) It makes me laugh how much the "magical triangle" crowd LOVES to spout off about efficiency only based on displacement and power. They forget to add in BSFC and thermal efficiency! OOPS! :banghead: You want to increase quench to help with combustion efficiency? Oh...wait...you can't! Anyway, I could go on and on, but there is a statement that I saw a long time ago that sums it up pretty well: If the rotary engine is so great, then why is it that there is currently only ONE manufacturer producing ONE car in limited quantities in the world with that type of engine in it? :confused: Things that make you go "HMMMMMMM"...:nod:

[RoadWarrior222]

Actually they might work better on low low octane for quicker burn... like mix a quarter tank of kerosene.

[zin]

I can't contest the fuel efficiency "dis", while it made big power (n/a), it DRANK fuel!

Mike

[shackwrrr]

LMAO!! If there was ever a perfect example of how inefficient a ro-tard-rie is...that is the one! The EGT's are usually through the roof on those things! How does this relate to being inefficient you ask? Well, if the EGT's are that hot, that means some combustion is still happening when the exhaust port is exposed, so it is just throwing away power and energy! (part of the reason they can spool huge turbos) It also increases emissions. There is really nothing that can be done about it either. (I'm not saying something can't be done) It makes me laugh how much the "magical triangle" crowd LOVES to spout off about efficiency only based on displacement and power. They forget to add in BSFC and thermal efficiency! OOPS! :banghead: You want to increase quench to help with combustion efficiency? Oh...wait...you can't! Anyway, I could go on and on, but there is a statement that I saw a long time ago that sums it up pretty well: If the rotary engine is so great, then why is it that there is currently only ONE manufacturer producing ONE car in limited quantities in the world with that type of engine in it? :confused: Things that make you go "HMMMMMMM"...:nod:

That and a 1.3 rotary is really a 3.9. They only count one face one each magical triangle. So can we the 2.2 a 1.1 since only 2 cylinders are at tdc at a time lol.

[Reaper1]

That and a 1.3 rotary is really a 3.9. They only count one face one each magical triangle. So can we the 2.2 a 1.1 since only 2 cylinders are at tdc at a time lol.

Their argument is that the eccentric shaft turns 3 times for ever 1 time of the rotor, so they argue that it equivalent to 1 combustion event per revolution of the eccentric shaft per rotor. I can only imagine the whining and moaning from that crowd if somehow a reciprocating engine had the crank turn 1 revs per 4 complete cycles of a cylinder and we claimed the same!

[johnl]

It's obvious but it bears stating - the compression rings have zero direct oiling.

They only get indirect oiling by way of whatever gets by the oil control ring and whatever it leaves on the cylinder wall.

[johnl]

www.ercracingfuels.com (http://www.ercracingfuels.com/)

ERC Racing fuels has supplied fuel and lubricants to racers for 40+ years; I asked Rick Gold, the owner, this same question about two cycle oil as a top end lubricant in turbo car fuel.

He recommended it without reservation. His preference is triple degummed castor bean oil, specifically Blendzall and then Redline synthetic, both at a fairly rich dilution for a four stroke of 1 ounce per gallon. Less than that he regards as a waste.

I asked him about detonation, his words are in blue -

"Everybody knows" that premix detonates easier thanthe same gasoline if it is not tainted with oil.

I WOULD CALL THAT PIECE OF 'COMMON' KNOWLEDGE URBAN MYTH AND THEACCEPTANCE OF "FACTS NOT IN EVIDENCE". INDEED THE OLDTIME INDY RACE MECHANICS ADDED PRODIGOUS AMOUNTS OF CLEAN CASTOR TO THEIR METHANOL BECAUSE THEY BELIEVED THAT CASTOR IN THE FUEL WOULD CENTRIFUGE OUT INTO THE PERIMETER END GAS REGIONS OF THE CYLINDER/COMBUSTION SPACE AND, BECAUSE OF IT'S HEAT SEEKING PROPENSITY, ACTUALLY PERFORM AS AN ANTI-DETONANT.



MOREOVER, I'VE NEVER SEEN ANY OCTANE NUMBER REDUCTION AS A FUNCTION OF USING TOP OIL IN ANY OF THE FUEL BLENDING THAT WE DO HERE AT ERC.




So, adjust the tune for the changes that the oil brings to it.

[wallace]

In pump fuel you've already got all sorts of additives to clean and lubricate. The top end lube they sell specifically for methanol that has all the different "flavors" is probably nothing more than the castor oil your guy referenced. There's definitely still some oil film on the cylinder walls after the oil control ring has done its job no way it gets all of it off of there so the compression rings do get some lubrication from there as well. That being said I don't see how it would hurt to add it if you wanted to. I'd be interested to know if it changes the tune up significantly by adding it.

[zin]

...There's definitely still some oil film on the cylinder walls after the oil control ring has done its job no way it gets all of it off of there so the compression rings do get some lubrication from there as well...

This is true on a number of levels, but most notably due to the fact that the flame front "quenches" before it actually gets to the metal surfaces, which leaves a film un-combusted... The lubricity of that film is up to whatever it consists of.

Mike

[johnl]

Still, the fact of taper, of upper cylinder wear occurring at a greater rate than both mid and lower cylinder wear, indicates something.

I haven't measured that many cylinders, so, do you typically see a waisted (as in a girl's waist) cylinder? That is, is it typical to see smaller cylinder dimensions in the center of the stroke, in that area where the piston has the highest speed and lowest load, as opposed to the top and bottom where the piston decelerates and reverses direction, where the rings slow down enough to get a bite, and where rod angularity is greatest?

[wallace]

You will definitely see wear in the middle of the bore compared to the top..not so much at the bottom. the machinist I use for block work increases the pressure on the honing machine at the top of the stroke to even that out, he uses a manual Sunnen machine. Looks really odd when you see him doing it but when he measures with the bore gauge it's straight with no taper. I think the wear is something that is going to happen no matter what kind of lubrication you would use.

[zin]

When I ran the Sunnen, I'd sometimes have to hit "dwell", which would have it pause at the bottom, not the top. The top always is looser, maybe he was running a bit heavy on the stone pressure, and had to straighten things out? If you apply too much feed pressure it can distort the cylinder walls, pushing it out in the middle, giving an hourglass shape, usually because the walls are thin (and therefore flexible) where they aren't supported by the decks or webbing in the bottom. When that happened for me it was usually because I was trying to go faster than I should..

Mike

[wallace]

I asked him about it and next time he was setting one up he showed me how the bore up near the top was worn and above there it got tight again. His explanation was the most wear was occuring at the top of the stroke..the piston will rock in the bore and so the wear is accelerated there. above this area it gets smaller again..we're only talking tenths here but you could see it on the gauge. The bottom showed very little variation after the worn area at the top. this was a a hone only no bore.

[zin]

That is true, it is due to the fact that the rings (on most engines) don't go to the top of the bore, so wherever the ring starts/stops and is under the highest pressure (top of the bore), is where the greatest wear/deformation occurs.

This is what creates the "ridge" at the top of the bore and generally prevents you from removing the pistons without using the ridge-reamer to remove that step, well, at least without breaking off the ring lands!

The deck also stiffens up the top of the bore, and will show "tightness" at the top of the bore as seen on the "pressure" gauge on a CK-10 type machine. Ideally, when honing, you're going for a minimal movement of the needle on the indicator, which means a straight bore.

Different blocks have different characteristics, but in general, after the ridge is removed, worn bores will tapper large to small in a top to bottom fashion...

Mike

[Reaper1]

Cars running meth as their fuel NEED oil in the fuel to provide extra lubrication because straight meth will wash the walls of any oil left there and cause very accelerated wear. Meth also has a VERY high octane rating anyway and burns very cool.

[zin]

There ARE oils/lubricants that won't contribute to octane degradation/detonation, though I've not done the research to discover what types or chemical properties provided that protection ... I'm very interested in any info along these lines if anyone has it to share. One place I know of its use is in sealed oil sumps of some roots style blowers.

Mike

[johnl]

In re-thinking it, rod angularity and therefore piston side thrust, is greatest somewhere in the middle of the stroke, and that is consistent with what Wallace is saying about greater skirt/cylinder wear in the center of the stroke.

[zin]

Side loads are virtually non-wearing on the cylinder wall, the piston can be another story... I think a picture here would be worth a 1000 words... The typical wear on a cylinder will have a step at the top, where the original bore is untouched by the rings, this is where the ridge forms, just below the ridge is the point of greatest wear/deformation, which will then tapper down the cylinder bore along the point of contact with the rings, stopping at the lowest contact point of the oil rings (max).

I'm probably just misinterpreting what's being said and drawing the wrong picture in my mind... from the descriptions I'm imagining the bore wearing in an outward bow-like fashion, rather than a simple tapper below the ridge as is normal...

Sorry if I'm being confusing here...

Mike