Subthread 32:1 vs 50:1 (heat data)

[Harley]

My theory on the gas was that when you change brands and thus additive packages that the properties of the gas would change. My thinking is that if we change the boiling point of the gas and oil mix it will affect the temperature that is seen on the outside of the cylinder.

In other words my latest theory is that the temperature readings were different on the cylinder because you change the boiling point of the mix by changing the amount of oil in the mix. A higher percentage of oil leads to a higher boiling point, and a higher cylinder temperature.

I think the same thing will be shown when you use different brands of oil anyhow. As the oils should have different properties.

Just an idea.

 

[bwalker]

Higher boling points would lead to lower temps as they would require more btu's to vaporize the fuel before combustion.

 

[Hexan]

I dont know how old this thread is, but WOW I was wondering on this same topic, and before a made another post about something that has been asked before; I checked and found this amazing thread. Learned more than I thought possible.
Hats off to you guys, your knowledge on this topic is nothing short of amazing. Keep up the good work.

 

[pallis]

It's late, and I haven't read through all the responses, but one possible explanation is that the greater the oil mix, the leaner the saw is going to run. 32:1 means less fuel per air mix than 50:1. The leaner the saw runs, the hotter it runs. To test it you might start with 50:1 and work down, adjusting the carb as you go.

Pat

 

[max2cam]

I read this amazing topic a while back on Fish's advice. At the end of it, however, I still didn't have any firm conclusion or conviction to go by.

Stick to the manf. 50:1 and some guys will laugh and say its just the EPA out to DESTROY your saw. Gotta run 40:1 or even 32:1 to be on the safe side. Or does more oil mean more heat and more carbon?

What to believe?

www.atthecreation.com

 

[Gen MacKartter]

oil up

Back in the days I raced Karts Mac had a study and found that 10/1 was best power and 15/1 was the best to run so you dont have plug problems with the best power also I dont know what additives they had in the oil

 

[geofore]

Btu's

Oil has more Btu's than gasoline per gallon and no ones has shown the tables for the Btu's. The heavier the oil the more Btu's. It's real easy to do a test if you have an old VW that had a diesel engine. They would run on diesel or gas. Which would give you better mileage? I used to run the old Jetta on diesel in the summer and gas in the winter because the VW started better in winter on gas, no glow plugs. Diesel gave better mileage by far. If you could get coal oil, that was heaver than water, it gave even better mileage than diesel. Does your new diesel truck get better mileage than your old gas burner? So, is the higher temp due to the higher Btu's of the higher oil content? You need to consider all factors when doing these experiments not just the ones you think count. Does a few more BTU's per gallon make a difference in temperature when you burn a gallon? My thought was you needed to atomize the mix to ignite it not vaporize it, think fuel injection. Vaporizing works but few of us run saws on propane or natrual gas or have preheaters on our carbs. Just a thought.

 

[bwalker]

Or does more oil mean more heat and more carbon?

I can garauntee you you that more oil does not leed to more deposits. Actually the opposite is true.

you needed to atomize the mix to ignite it not vaporize it

Liquids do not burn. Ever throw a match into a container of gasoline? Notice only the vapors rising off the liquid are burning. Ever wonder why a two cycle smokes like heck when started in cold weather? Its because un vaporized fuel is making it to the combustion chamber.
In a warmed up engine fuel enters through the intake port in micro droplet form. It imediatly begins to vaporize as it comes in contact with hot engine parts in the crankcase. This leaves behind the oil that is carried into the engine via the pre mix to lube your bearings, rings etc. By the time the mixture makes it up into the combustion chamber almost all of the fuel is vaporised. Whats hasnt(ie high boiling point compnents) is flash vaporized when the spark plug fires or is never burnt and goes out the engine intact. The latter hapopens often with todays poor quality pump fuel and especially with RFG fuel due to its limits on volitility.
Now the issue of the BTU of premix oil vs. the btu of gasoline. Modern premix oils are general made up of a blend of oils. Usually the blend will include some stoddard solvent, a light weight paraffinic base stock, and a poly iso butene(replaced bright stock AKA heavy petrol residium). None of these components are of a really high molecular weight. When one considers the added heat required to vaporze these components I think their het contribution is a wash. Besdies the differance between 32:1 and 50: is a miniscule amount of oil. I thihnk its farely apparent that the methodologies of this"study" are full of holes.

BTW geofore. your diesel vw gets better mileage by virtue of its highers compression ratio and more efficiant engine. Not to say the higher btu content does contribute, but gasline has a btu of 125k abd diesel 135k. Less than 10%

 

[geofore]

Heat of vaporization

So, what you are saying is to disregaurd the energy lost in Btu's to bring the fuel up to the heat of vaporization from its atomized state when it enters the chamber? Then ignore the higher heat value of the heavier oils because they take more energy to bring up to the heat to vaporization? There is so little oil in the gas the btu's don't matter? If it didn't matter why did the industry go to synthetic oils from dino oils? Just (wise)cracking off a few heavy molecules or breakdown due to heat transfer or the lack there of?

 

[bighoss550]

fuel affects a thing called dynamic timing. or "flame front travel". a more viscous fuel "slows the burn", giving the effect of retarded timing(although it actually doesnt), but it also lengthen the "burn time". this longer time to burn invokes more heat into the surround, simply from more exposure. higher dynamic timing also allows the burn cycle to progress farther down the stroke of the piston, which exposes more of the oil film to heat, which absorbs heat into the surround better than the cyl wall without the oil(above the ring line, where most of the burn takes place).

gas and oil come from the same dinosaur turd, so when mixed they are one again...... soooooo more oil=higher viscosity of mixture=higher dynamic timing=more heat

haha, questions???

 

[bwalker]

Flame fron propagation is controlled by the hydrocarbon makeup of the fuel, not by viscosity. Besides I would challenge any one to measure the viscosity differance between a 32:1 mix and a 50:1 mix. You only talking about a 1.4 oz differance in oil content between the two.

So, what you are saying is to disregaurd the energy lost in Btu's to bring the fuel up to the heat of vaporization from its atomized state when it enters the chamber? Then ignore the higher heat value of the heavier oils because they take more energy to bring up to the heat to vaporization?

No, I am saying consider the effect of the above.

There is so little oil in the gas the btu's don't matter?

Yes, the differance bewteen 32:1 and 50:1 is 1.4 oz. 128oz of gasoline are in a gallon. I would call the differance minuscule.

If it didn't matter why did the industry go to synthetic oils from dino oils?

When did they do that? Most oils are still only partial synthetic. I dont see how synthetic oil would be germain to this thread.

 

[bighoss550]

been buildin pulling tractors for years and that was in laymans terms outta a book. the viscosity of the fuel does have an effect.
the tractors that burn alky have done endless testing on the effects of how much lubricity and viscosity is in the fuel, and the affects on performance.

the HC makeup of fuel does have an affect, but the aditive is where u get ur difference. 93 octane is 87 with additives most of the time. some refineries do it differently but they still add crap to it to get the #'s they are looking for.

another thing i thought of is that oil in the chamber is a detonant. the more oil u have in the chamber the less stable the charge is. thats why race engines have such good PCV systens. this may be another contributant to the heat with more oil. although this may not have as much effect on the 2 stroke........ not sure there

 

[bwalker]

Which book are you refering too? I wpuld like to read it
As far as oil being a detonate? How so? Is peanut butter a detonate?

 

[bighoss550]

probably is if u could get it in there. and the book is the hi-po fuels class textbook from college. its about 3.5" thick........ not a real page turner but good for info...

im not tryin to argue, just posting what knowledge i have to help.... nor am i saying that i know the answers.... especially when it comes to a gasser 2 stroke.
diesels, i know....and all int comb engines share principles.... just tryin to help

 

[bwalker]

Give me the author and title. I would like to read it.

 

[yungman]

This is a very interesting test and I have been reading all the comments.

1) I don't believe increase from 1 oz to 1.56 oz of oil into 50 oz of gas will change the air fuel ratio enough to cause the observation of temperature difference. The gas ratio only change by about 1% only in the air fuel ratio!!

2) The increase of oil ratio is a lot bigger, that is 156% change from 1 oz to 1.56 oz mix into 50oz gas. So what does this mean?

3) The difference of temperature of the exhaust gas is a lot smaller. The exhause temperature is measure at the output of the muffler, muffler is bolted directly to cylinder. Muffler may be heated up by cylinder which in turn heat up the exhaust gas. Measure at the exhaust port inside the muffler close to the exhaust port of the cylinder may give a more accurate reading of the exhaust gas temperature. If the temperature of the exhaust gas measure close to the exhaust port of the cylinder is lower with more oil, then we can conclude the rise of temperature of the cylinder is due to better conduction of heat with more oil.

4) Now let's assume that rising of temperature is not due to better heat conduction due to extra oil. Rise of temp from 80s to 95 really that much to cause premature wear? Will the little extra oil protection way offset the effect of rising temperature. No one can tell unless a ring wearing measurement is done, that will be hard.

This is the link of another person testing on oil, not the same context but from that you can see the temperature is not that big a difference.

http://www.geistware.com/rcmodeling/articles/oil_test/index.htm

I don't have an opinion that I can prove, I read too many opinions that cannot be substanciated. This and the other link is the only scientific experiment that I would take it more serious. If anyone have more of this kind of test result, please reply.

 

[Fish]

Well at least someone is looking at the old threads....

Dagger gave up on this crowd a few years back, too many hardheaded types
here.....................................................................

He is in the industry, and does not want to get drawn out here, but he does make some good posts, eh?

The important thing to keep in mind, is to keep an open mind , and learn.
If your testosterone levels will permit...............

Do not give this guy any guff, calling up old threads that educate, is no sin.

 

[husq2100]

ok most of this stuff is over my head!

just a coulpe of points im wondering,

is it agreeded that 32-1 will produce more power than 50-1, carb tuned to suit ratio?

if so more power would have to mean more heat?

and just because its hotter does it mean that the lubrication of the crank is worse , better at 50-1 than at 32-1???

heat is the byproduct of whats going on but does it means its worse or a bad thing?


serg

 

[yungman]

Iactually join this site just to get into this discussion. This can be a very important piece of info if everyone can put aside their eagle and join in to brainstorm. I notice people get very personal here which is really diverting all the energy to argue and away from the issue.

I live in the Bay Area, it is too bad that I live in place that neighbor are close by and is not easy at all to find a place away from people so I can go WOT and let it scream and do the experiment.

There are so many variable and changing one parameter can change everything. More test should be done and recorded.

Also I think it is useful to try running the experiment on different brand of oil at different mix ratio but keep the air fuel adjustment constant.( people don't adjust this and not even adjustable in the new models). Also monitor the carbon formation with different ratio also.

I hope I can start this thread up again to get people to do more experiments. All the other posts mainly talk about what oil ratio they use and why they think is better. Everthing is just an opinion even I really like to agree with. I always think 32:1 is the best, not enough to form carbon but more than 50:1 to get extra protection. But what is the point to talk, just get into more disagreements. Analytical result speak louder than everything. Like this one, it is so unecpected to see temperature rise with oil!!!!

Please join in, in a friendly way and lets share the experience.

 

[yungman]

I actually join this site just to get into this discussion. This can be a very important piece of info if everyone can put aside their eagle and join in to brainstorm. I notice people get very personal here which is really diverting all the energy to argue and away from the issue.

I live in the Bay Area, it is too bad that I live in place that neighbor are close by and is not easy at all to find a place away from people so I can go WOT and let it scream and do the experiment.

There are so many variable and changing one parameter can change everything. More test should be done and recorded.

Also I think it is useful to try running the experiment on different brand of oil at different mix ratio but keep the air fuel adjustment constant.( people don't adjust this and not even adjustable in the new models). Also monitor the carbon formation with different ratio also.

I hope I can start this thread up again to get people to do more experiments. All the other posts mainly talk about what oil ratio they use and why they think is better. Everthing is just an opinion even I really like to agree with. I always think 32:1 is the best, not enough to form carbon but more than 50:1 to get extra protection. But what is the point to talk, just get into more disagreements. Analytical result speak louder than everything. Like this one, it is so unecpected to see temperature rise with oil!!!!

Please join in, in a friendly way and lets share the experience.