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87 vs 93 octane


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quote:
Originally posted by hotrodtractor
93 is ethanol free by me.......thats what the tractors get
I just noticed the other day about the alcohol free super. Usually, super is a dime a gallon more than mid-grade. Out in Palmyra Kevin, alcohol free super is 30 cents more/ gallon than mid grade. I just wonder how much longer it's going to be before you can't get and ethanol free gas. Mark, When the fuel companies started supplying alcohol as an additive, they were in a pinch and added methanol to the fuel. Wood alcohol was readily available and the oil companies used it to meet the early demand. Yup, people were freaking out, getting sick, and their engines weren't running so well. At least this is what I understand about the early fuel additive
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Here is what the fuel companies have as ways of blending to increase octane. Isooctane, benzine which has many derivatives like Toluol and Xylol , trimethylbutane , trimethylepentane , n-butanol and t-butanol. There are others that they have in there cashe of petrochemical as well as stuff from the ether group. By the way Diesel fuel only has an octane rating of 28 on average. Fuel for thought.
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I use to use 89 octane in all my OPE and some of that was driven my the owners manual recommendations as a minimum. Now I try to go ethanol free and that means 93 at the one gas station I know of that has ethanol free gas. Bill
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quote:
Originally posted by 1Litre
Octane in the flat head engines requires less than 87 pump octane for the 7.8:1 to 8.2: comp ratio that they are. Hot days with air cooled engine will require more octane to prevent pre ignition or detonation that damage engine internals. Fuel is made for auto industry and the rest can adapt . Power in numbers rule applies here. Premium fuels have more than Ethanol to increase the the octane and those chemicals mostly Dymethyle Benzene(Toluol=Enamel reducer)are the main additive to do that. Those compounds are more stabil than the gasoline and will oxidize less and if the gasoline is goin bad and form soluble sludge ( first stage of oxidation breakdown )they keep it soluble in the gasoline too. That is why members claim less problems with the premium fuel. May even clean fuel system. Unleaded fuel forms less carbon than leaded fuel. Briggs and Kohler will tell you this. Unleaded fuel carbon deposits are hard and cause more internal damage.Good thing there is much less carbon over long use. Higher octane gasoline is more evapaorative ( tied to vapor pressure specs ) than lower octane fuels. Gasoline is complex stuff.
Pre-ignition pinging is what got me into the ethanol study. For me, it wasn't an exceptionally HOT DAY, but the long duration of the mowing, at 3/4 throttle, went into overheating symptoms. Pinging happened and more throttle did not deliver more power; it seemed like motor was losing power, and it puffed some traces of smoke when full throttle applied. It's possible that the K341 had some carbon to blow out; but the switch to premium gas eliminated all symptoms. No problems since. That's my main reason for using premium in the 716. (Also possible that carbon buildup slightly increased the compression, so higher octane. Someone else here mentioned that). Main thing for me is I feel more confident and carefree using 93 gas; and my 'boy tractor' seems more 'frisky'. 8D My "pacer" mower (13.5hp Briggs Intek) gets it too; but it needs some tlc generally - in the meantime, it seems better starting and running on the good stuff. It needs some basic tune, plus has a ground/charging issue that's really hard to get at. blablabla. sm01
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Higher octane gasoline burns slower which is why it is required in high compression or turbo/super charged induction. In such motors the heat and pressure cause the lower octane fuel to ignite before the compression stroke is complete and the spark plug ignites and you get pre detenation and pinging.
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quote:
Originally posted by mjdkraft
Higher octane gasoline burns slower which is why it is required in high compression or turbo/super charged induction. In such motors the heat and pressure cause the lower octane fuel to ignite before the compression stroke is complete and the spark plug ignites and you get pre detenation and pinging.
Thank you, Mike - I didn't know, or fully realize, that; and that's a missing link in the puzzle for this kid. sm01
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That's quite the education I really am impressed. OK so We determined the 5 gal won't hurt it. Know I'm wondering if I should stick with the 93. Both sides have good arguments. For me it's as simple as sticking with the owners manual. high quality reg grade gas. that's what shes getting. Unless the tractors engine performance starts indicating otherwise I'm sticking with 87 octane ethanol free from the Indian reservation.
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quote:
Originally posted by mjdkraft
Higher octane gasoline burns slower which is why it is required in high compression or turbo/super charged induction. In such motors the heat and pressure cause the lower octane fuel to ignite before the compression stroke is complete and the spark plug ignites and you get pre detenation and pinging.
Another old shade-tree mechanic's story that's not true. Higher octane gas requires a higher combination of pressure and temperature to self ignite (detonate) period. [url]http://www.whitfieldoil.com/www/docs/171.284/rockett-brand-race-fuel.html[/url] OCTANE NUMBER: The octane number of a gasoline has little to do with how fast it burns or how much power the engine will make. Octane number is the resistance to detonation. If the octane number is high enough to prevent detonation, there is no need to use a higher octane gasoline since the engine will not make any additional power. Octane number is not related to flame (burn) speed either. Variations in octane quality are independent of flame speed. There are some high octane gasolines in the marketplace with fast flame speeds and some with slow flame speeds. It depends on how they are put together. We prefer fast flame speeds because we know that a properly tuned engine will make more power on this type of gasoline than one that has a slower flame speed.
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Well that's funny because the state you live in says otherwise. I'm sure there are a host of variables between fuel brands and every manufacturer might tell you something different. All I know is that higher heat and pressure requires higher octane to prevent pre-ignition. http://mn.gov/commerce/weights-and-measures/images/OctaneFacts.pdf
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Bureaucrats often get technical things wrong. Here's another link to the subject written (as was the first link) by a technical source. [url]http://www.rockettbrand.com/techsupport/documents/TechBulletins/FlameSpeedOctaneAndHpRelationships.pdf[/url] Also apply a little common sense. What kind of engines run high compression and require premium fuels?? They are usually high performance or racing engines-------------engines that operate at much higher rpms than "normal" engines. A fast flame speed is essential in these engines to maximize hp.
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Do you realize that both articles are the same text but on different web sites. A stock pontiac grand prix gtp, which is a supercharged 3.8 litre v6 is not a racing engine but one that does require higher octane fuel and does not run at any higher rpm than the "normal" small block v8 in my gmc pickup. In order to return this to the original topic od this post, 93 octane is fine to run in your small engine, there is no benefit or drawback other than a little more money. I guess my "commom sense" was lost somewhere along the way.
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I found the (idea, notion, concept) to be helpful in understanding what my non-racing tractor was doing. At the time, Al Eden jumped in with some amazing info and experience with exactly my engine. The fix he experienced with K341's was to use TEST with double head gaskets which reduced compression, and he also spoke of grinding the combustion chamber larger, to permanently reduce compression, and avoid preignition. It was also suggested that carbon buildup could effectively increase compression, and hence preignition occurred at high temps, hot days, long running duration, etc. I don't doubt there are many wonderful theories; but for me, the idea worked. The switch to premium apparently alleviated high rpm, high heat, prolonged running PING. The old k341 ran better - period. Nothing else was changed, altho I did consider tweaking the jet setts. But in all this, even if low octane E10 is adequate, it's tendency to pickup water, and separate, fairly quickly is the problem. It's shelf life is rated as some 3 weeks. I doubt that - maybe a few days, is more like it. So expecting good performance from water, separated goo, and whatever true gas actually remains = FAIL. Alcohol generally is known in chemistry as a 'drying agent' - therefore, no surprise, ethanol absorbs water - right now - unless there is no air in the gas tank. Since my tractor doesn't use that much gas, the extra cost is a small price to pay, to know I am feeding it gasoline, rather than something that's dependent on rocket science O2 sensors, and computer controlled injectors, or whatever, to make it somehow acceptable to the gov vs the oil companies vs big biz, etc etc etc where's the truth, and how is it useful for us to not have the truth readily available, if not for mere profit motives. It's not about the wannabe "green movement" - sorry, I see only compromise, and coverups. So I compromise my way, with whatever best info I can get. I remain open to better suggestions - there's nothing to lose, the loss has already happened; and I think it continues through dysinformation - a popular marketing tool these days, keeping people in the dark like mushroom bla bla bla, etc. Nothing new there. It seems we insist on supporting it, or ignoring it, and then discussing our own better ideas, to hopefully avoid troubles, or attain advantage - is this really our job?
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Back in my miss spent youth I worked in a Mobil Station, at that time they claimed Mobil reg was rated over 100 octane. That was back in the 50's. Arguing about gas is like arguing about politics. Like they said in the 60's if it feels good do it.:D
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so one more variable to add to the equation. The use of sta-bil. The old fashioned red stuff in every 5 gal can of 87 i use. Good or unnecessary.
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I can not find independent testing on fuel stabilizer agents. There are other stabilizing products with the word Enzyme in the product description for ethanol gasoline fuel. Enzymes help break down substances called a reaction. What is the Enzyme breaking down in the fuel? Gasoline ? soluble sludge that forms as the gas is going bad ? Ethanol ? I do not know . More has to be asked of compaanies that make the products and data to support the product they sell. If you do not ask they just go on taking the money. Manufacturers of engines may provide the answer when they test products in their engine and sometimes a recomendation is made by them. Briggs has their hat in the ring with the stabilizer branded with their name. I use stabilizer . I look at it like it can not hurt. I know for a fact that the older the fuel it gives up startability and octane . Plastic containers are not all what they seem to be. Some parts (light ends) of fuel will leach right threw the container.
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I've used stabilizers - didn't seem to hurt anything. I only use it overwinter storage. things run better with new gas, but at least they startup in spring. I'm tempted to experiment w isopropyl; try to run a semiformal experiment on 87octane - small amount, eyedropper? ????.no numbers/ratio.??? I linked that idea back on pg 1. Perhaps useful for delete xs-H2O in system, maybe, and occasionally, onetime treatment - not a full time diet, unless perhaps a very tiny amount - buy how would I know it's working? or damaging? Easier to use good gas; I keep coming back to that - I don't notice problems, some problem symptoms disappear. So, that works for me; and that's what I do. But is has also moved to a feeling of confidence vs worrying about the deterioration reported. but - yes to overwinter stabil. and run it in.
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quote:
Originally posted by MysTiK
I found the (idea, notion, concept) to be helpful in understanding what my non-racing tractor was doing. At the time, Al Eden jumped in with some amazing info and experience with exactly my engine. The fix he experienced with K341's was to use TEST with double head gaskets which reduced compression, and he also spoke of grinding the combustion chamber larger, to permanently reduce compression, and avoid preignition. It was also suggested that carbon buildup could effectively increase compression, and hence preignition occurred at high temps, hot days, long running duration, etc. I don't doubt there are many wonderful theories; but for me, the idea worked. The switch to premium apparently alleviated high rpm, high heat, prolonged running PING. The old k341 ran better - period. Nothing else was changed, altho I did consider tweaking the jet setts. But in all this, even if low octane E10 is adequate, it's tendency to pickup water, and separate, fairly quickly is the problem. It's shelf life is rated as some 3 weeks. I doubt that - maybe a few days, is more like it. So expecting good performance from water, separated goo, and whatever true gas actually remains = FAIL. Alcohol generally is known in chemistry as a 'drying agent' - therefore, no surprise, ethanol absorbs water - right now - unless there is no air in the gas tank. Since my tractor doesn't use that much gas, the extra cost is a small price to pay, to know I am feeding it gasoline, rather than something that's dependent on rocket science O2 sensors, and computer controlled injectors, or whatever, to make it somehow acceptable to the gov vs the oil companies vs big biz, etc etc etc where's the truth, and how is it useful for us to not have the truth readily available, if not for mere profit motives. It's not about the wannabe "green movement" - sorry, I see only compromise, and coverups. So I compromise my way, with whatever best info I can get. I remain open to better suggestions - there's nothing to lose, the loss has already happened; and I think it continues through dysinformation - a popular marketing tool these days, keeping people in the dark like mushroom bla bla bla, etc. Nothing new there. It seems we insist on supporting it, or ignoring it, and then discussing our own better ideas, to hopefully avoid troubles, or attain advantage - is this really our job?
First, repeating old shade tree mechanic's stories is "dysinormation." Second, I'll go back to flame speed with another reference and quote: The antiknock ability is related to the "autoignition temperature" of the hydrocarbons. Antiknock ability is _not_ substantially related to:- 1. The energy content of fuel, this should be obvious, as oxygenates have lower energy contents, but high octanes. 2. The flame speed of the conventionally ignited mixture, this should be evident from the similarities of the two reference hydrocarbons. Although flame speed does play a minor part, there are many other factors that are far more important. ( such as compression ratio, stoichiometry, combustion chamber shape, chemical structure of the fuel, presence of antiknock additives, number and position of spark plugs, turbulence etc.) Flame speed does not correlate with octane. [url]http://www.faqs.org/faqs/autos/gasoline-faq/part3/[/url] Third, while it is theoretically possible for E10 to become saturated with water and go into phase separation, it rarely happens. When it does happen, it's due to very poor fuel handling and storage. I buy E10 for my "fleet" of air cooled engines, three 5-gallon cans at a time. That will last me a couple of months in the summer and 3-5 months in the winter. I also store a motor home with a 75 gallon fuel tank full of fuel each winter for 5-6 months. I also store my boat for a similar length of time each winter----also with a full fuel tank. My 67 Vette gets stored year around. It only gets driven a few times and maybe 2-3 miles a year total due to worn out suspension bushings. It gets refueled about every 3 years. The gas mixture for my 60's vintage McCullough chain saw also lasts several years before I need to buy and mix another can of it. I have yet to run into the problems with stratification that the E10 haters like to talk about. And, for what little it's worth, I'm a retired engineer with lots of experience with engines plus 45+ years of membership in SAE. I have learned to separate the truth from the many urban legends that often circulate.
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This is all good information. The point I try to make is about ethanol in gasoline and Premium versus regular and what the ethanol had to do with it. I did not want to get into flame speed or even octane so much as to confuse the whole issue. I said before gasoline is complex stuff. I should have added that the internal combustion taking place in all of our engines is complex with every component the fuel air mixture comes in contact with effects the result of the combustion . Maybe we should compile the info here under FUEL heading in its own forum topic with stabilizers and other additive members have had experiance with. There is other info from the Fuel companies that could be included for everyone to make informed decisions on there fuel choice. Please nobody mention octane booster or fuel system cleaners here or the Webmaster may have to buy more server space.
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quote:
Originally posted by 1Litre
This is all good information. The point I try to make is about ethanol in gasoline and Premium versus regular and what the ethanol had to do with it. I did not want to get into flame speed or even octane so much as to confuse the whole issue. I said before gasoline is complex stuff. I should have added that the internal combustion taking place in all of our engines is complex with every component the fuel air mixture comes in contact with effects the result of the combustion . Maybe we should compile the info here under FUEL heading in its own forum topic with stabilizers and other additive members have had experiance with. There is other info from the Fuel companies that could be included for everyone to make informed decisions on there fuel choice. Please nobody mention octane booster or fuel system cleaners here or the Webmaster may have to buy more server space.
There has always been "old wives tales" about things. The internet has made that much, much worse. Bottom line on the subjects brought up in this thread: 1. The only "need" or benefit for premium gas is in a high compression engine where it is specified or in an engine that has combustion knocking. 2. There are only a few circumstances where fuel additives might be helpful (other than to the companies marketing them). One is for long term storage (more than 3 months). That includes the mouse-milk sold to add to E10. I use Stabil in my motor home and boat when I put them away for the winter. The '67 Vette also gets it. I don't bother adding it to the '03 Vette as I sneak in a drive now and then during the winter. Nor do I treat the lawn and garden engines that sit all winter. 3. A fuel system cleaner is not called for unless you are actually experiencing a problem. Keeping a fuel system clean is one of the side benefits of E10. If you are actually experiencing a problem, the cleaner that is best regarded is Techron. Sea Foam is also well regarded. I prefer to use my money for more toys-------not for unnecessary additives or buying more expensive fuel than is necessary.
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Cool that's what I needed to know. You're right that sta-bil is expensive. adding it in every tank. I don't think I need to. It's unnecessary, from what you guys have taught me. It doesn't treat ethanol either. Now from what I've learned from you guys I don't think I have much to worry about. Unless there is a problem, treat the problem. The proactive measures Ive been taking is a little unnecessary. Well better safe than sorry I guess. All I wanted to know was If I was Hurting anything. So the answer is no. Just my wallet. Oh well better safe than sorry.
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