Premium Fuel

[chris63]

When you guys mention "fresh"gas what do you mean?How long do you think it sits at the refinery before it ends up at the pump?Also I think the gas in general is a poorer gas than in "the old days"Just some things to think about.Now go fish!!! c63Oh yea if you want some good stuff get it at the small regional airports around the state,now thats what I call flash point!cyac63

[Gator Slayer]

Sorry to create a contentious post.... I was aware of the potential for gumming/varnishing and that's why I've used premium as a hedge....not a guarentee. The salesman stated that premium fuel has too high of an octane rating and could lead to "Damage" to a new engine since it will burn hotter. That's what I was curious about. I'm gathering from the fact that many people use premium in a variety of engines that is should be OK. Thanks to all who posted.

[Jeremy airjer W]

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The salesman stated that premium fuel has too high of an octane rating and could lead to "Damage" to a new engine since it will burn hotter

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The higher the octane rating the harder it is to burn. I don't think it burns hotter? (somebody correct me if I am wrong!) Or another way to look at it is the higher the octane rating number the more resistance it has to ignite. This is why higher octane fuels are a great diagnostic tool to determine if the customer is actually hearing "ping" and whether or not it is a carbon buildup issue. The higher octane fuel will resist the temptation to pre ignite, ping goes away. Many premium fuels also contain premium cleaners, remove the carbon remove the ping. If the vehicle is normal with the next tank of regular problem solved if not I'll tell them what wrong but they have to show me the $$$$

A little off topic but worth mentioning!

[Eric Wettschreck]

I don't know aboot the higher octane rating, but oxy fuel with 10% ethanol will burn cooler than with no ethanol. Ethanol has less BTU's than gasoline and will burn cooler.

[Pat K]

Airjer

The higher the octane, the higher the flash point. It has to burn at a higher temp.

[pfluemis]

All righty then, lets dispell some myths with facts.

1) Ethanol does not harm fuel systems, but that ugly toxic fuel Methanol does.

2) Ethanol has less energy/BTU's than gasoline, therefore it does not create as much power when ignited.

2) Ethanol is about 100 octane. This, when mixed with gasoline, allows refineries to use a little lower grade gasoline to achive the 87 octane. This is why you can experience gasoline related issues with older gasoline. The base fuel is sub-standard grade, and the ethanol has broke down/evaporated, so your left with sub-standard fuel in the tank/carbs. It's a crap shoot whether you will be left with usable fuel or not the next season.

3) Premium fuel does NOT burn slower.

4) Premium fuel has a higher flashpoint, meaning it is more stabil in the combution chamber, not that it takes a noticable increase in the amount of heat needed to burn. Meaning, Premium fuel does not have a noticeable increase in BTU's.

5) Adding stabilizers to fuel is only as good as the stabilizers and fuel. Meaning, if you add old stabilizer to good fuel, shelf life will not be very long. Same with adding fresh stabilizer to old fuel. Adding old stabilizer to old fuel is about as pointles as things get. Stabilizers, such as the brand name stabil, have a shelf life of about 18 months. 18 months from the time it was produced, to the time it is used, NOT 18 months from the time you took it home from the store. Other stabilizers will perform better and last a little longer. Sea-foam, IMO is a superior product becouse it is packaged in a metal can and light does not break the product down.

6) Ethanol is not the answer to Americas or the worlds energy energy needs, but it's a start.

7) True, field corn ethanol is not a very good ethanol, the sugar content is very low. The input to output ratio is low. BUT, there are a lot of options out there to make ethanol a much better product. Grasses, sugar canes, even some waste products like citrus peelings. Sugar cane for example, is a 10:1 ratio. For every 1 BTU used to produce it, you get 10 back out. In theory, an ethanol plant could power itself by using the energy it produces, to make more energy.

8) Ethanol is non toxic as is, or being burned. It's freaking ALCOHOL. The rumors that it is toxic are false. Methanol on the other hand, is very toxic. I think they get mixed up sometimes becouse they sound simular, and are both additives.

9) The sad part of the whole thing is, fuel prices will drop soon, and people will go back to the way things were a few years ago. Then, in 15 years, this will happen all over again, and we will be back to where we are right now. I just hope people will some day educate there children on the perpetual cycle of oil prices, and that there is something that can and should be done about it. 15 mpg commuter vehicles is not the future, it will be the end, as will be living for today. If everyone "lives for today", soon there will be no tommorow. Ok, I'll step off my soapbox now.

[papabear]

Ive been told that my 25 horse merc needs premium to run better. Fought with it two years before found place that sells premium at reg price. Now it runs well and can troll again with it. Premium is regular with ethanol added or is it something else?

[Jeremy airjer W]

Another thread that may interest you is the discussion we have been having on seafoam in the equipment and expert info forum. page three has some specifics on seafoam and why it works.

Seafoam question

[LMITOUT]

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Ive been told that my 25 horse merc needs premium to run better. Fought with it two years before found place that sells premium at reg price. Now it runs well and can troll again with it. Premium is regular with ethanol added or is it something else?

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There's two different kinds of premium at the pump: One is the higher octane and contains ethanol. The other is non-oxygenated (no ethanol) and is identified by a sticker that says so. If it has no sticker, then it contains ethanol. Not all stations carry the non-oxy premium.

[BobT]

As the piston in your engine reaches near the top most point of its compression stroke the spark plug will fire to initiate fuel ignition. The timing of this is critical so that the energy from the burning fuel will reach full power as early as possible but not too early so that it tries to push the piston backwards. In this way the fullest extent of the force of the expansion is applied to the top of the piston on its downward stroke (power stroke). The timing of the spark is not at the exact moment the piston reaches the top of its stroke (top dead center) but is actually a bit earlier (perhaps a few degrees) to take into consideration the amount of time needed for the fuel to ignite.

Gasoline rated at 87 octane is less stable, will ignite more easily, and will burn more rapidly than 92 octane. Simplified, 87 octane basically explodes compared to 92 octane which burns. Using 87 octane fuel in an engine designed for 92 octane can cause damage because the 87 octane may ignite too quickly. The result is similar to advancing the ignition timing. The audible knock we hear is the expansion occurring so early that it is trying to push the cylinder backwards and we hear the piston rod and cylinder collide with the fuel. When I was younger we used to time engines by ear and we could tell immediately if we were too far advanced because we could hear the knock. Of course, this was crude at best because knock isn't always audible.

Using 92 octane in an engine designed for 87 octane can also cause damage and is penny-wise and dollar-foolish. My truck’s owner’s manual specifically says to expect lower fuel economy using high octane and they were right. Using 92 octane fuel in an engine designed to use 87 octane will not allow the engine to take full advantage of the energy generated by the expansion from the fuel because it will ignite too late and burn too slowly. The fuel will still be burning after the piston has completed its power stroke so the excess heat is now being absorbed by the exhaust system.

Just like engine design there are many other factors involved but let me try this analogy. Black powder (low octane) is a significantly slower burning fuel than smokeless power (high octane). If one measures each powder charge to produce the same BTU output there will still be a dramatic difference in the velocity of a bullet fired from the same gun. If the gun is designed with a barrel length that takes fullest advantage of the burn rate of smokeless powder, the bullet will reach its highest muzzle velocity using smokeless. Now measure a charge of black powder that will produce the same BTU output and the muzzle velocity of the bullet in this gun will be lower. This is because the bullet wasn’t able to take full advantage of the energy generated by the fuel. Because the black powder burns at a slower rate, the gases in the chamber and barrel expand at a slower rate resulting in a slower bullet velocity. In fact, it burns so much slower that some of the powder will still be burning after the bullet has already left the muzzle (penny-wise and dollar-foolish). The shooter can feel the difference in the recoil (knock).

Higher octane doesn't necessarily mean better, only different.

Bob

[Dahitman44]

I agree with OUT -- use the Premium. Us eit is your lawn mower, trimmer, Ice auger, classic cars and 2 and 4 stroke.

Last year I heard of a guy that had fuel that was "super unleaded and after a month it could not be lit by a match. That is bad.

Also many mechanics in all fields say it is good to add a bottle of seefoam to most engines as well.

[pfluemis]

Quote:

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As the piston in your engine reaches near the top most point of its compression stroke the spark plug will fire to initiate fuel ignition. The timing of this is critical so that the energy from the burning fuel will reach full power as early as possible but not too early so that it tries to push the piston backwards. In this way the fullest extent of the force of the expansion is applied to the top of the piston on its downward stroke (power stroke). The timing of the spark is not at the exact moment the piston reaches the top of its stroke (top dead center) but is actually a bit earlier (perhaps a few degrees) to take into consideration the amount of time needed for the fuel to ignite.

Gasoline rated at 87 octane is less stable, will ignite more easily, and will burn more rapidly than 92 octane. Simplified, 87 octane basically explodes compared to 92 octane which burns. Using 87 octane fuel in an engine designed for 92 octane can cause damage because the 87 octane may ignite too quickly. The result is similar to advancing the ignition timing. The audible knock we hear is the expansion occurring so early that it is trying to push the cylinder backwards and we hear the piston rod and cylinder collide with the fuel. When I was younger we used to time engines by ear and we could tell immediately if we were too far advanced because we could hear the knock. Of course, this was crude at best because knock isn't always audible.

Using 92 octane in an engine designed for 87 octane can also cause damage and is penny-wise and dollar-foolish. My truck’s owner’s manual specifically says to expect lower fuel economy using high octane and they were right. Using 92 octane fuel in an engine designed to use 87 octane will not allow the engine to take full advantage of the energy generated by the expansion from the fuel because it will ignite too late and burn too slowly. The fuel will still be burning after the piston has completed its power stroke so the excess heat is now being absorbed by the exhaust system.

Just like engine design there are many other factors involved but let me try this analogy. Black powder (low octane) is a significantly slower burning fuel than smokeless power (high octane). If one measures each powder charge to produce the same BTU output there will still be a dramatic difference in the velocity of a bullet fired from the same gun. If the gun is designed with a barrel length that takes fullest advantage of the burn rate of smokeless powder, the bullet will reach its highest muzzle velocity using smokeless. Now measure a charge of black powder that will produce the same BTU output and the muzzle velocity of the bullet in this gun will be lower. This is because the bullet wasn’t able to take full advantage of the energy generated by the fuel. Because the black powder burns at a slower rate, the gases in the chamber and barrel expand at a slower rate resulting in a slower bullet velocity. In fact, it burns so much slower that some of the powder will still be burning after the bullet has already left the muzzle (penny-wise and dollar-foolish). The shooter can feel the difference in the recoil (knock).

Higher octane doesn't necessarily mean better, only different.

Bob

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Now How come I post facts, and people who don't know what they are talking about have to come back and post BS????

"Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause knocking. (Note that it is the absolute pressure (compression) in the combustion chamber which is important - not the compression ratio. The compression ratio only governs the maximum compression that can be achieved).

Octane rating has no direct impact on the deflagration (burn) of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which deflagration takes place. In other words, the flame speed of a normally ignited mixture is not directly connected to octane rating. Deflagration is the type of combustion that constitues the normal burn. Detonation is a different type of combustion and this is to be avoided in spark ignited gasoline engines. Octane rating is a measure of detonation resistance, not deflagration characteristics."

[BobT]

True, all gasoline by itself all burns at the same rate. This is government mandated to protect the engines we use in our vehicles. However, the additives used to raise the octane level of the gasoline mixture we use DOES affect the burning rate of the fuel we buy and aptly refer to as gasoline. As I stated, there is far more that goes into this and my explanation was elementary at best but I think my illustration is still valid.

Bob

[Kyle Sandberg]

USE WHAT FUEL THE MANUFACTORER DESINGED IT FOR! They made the engine to be used with a certain gas so use it. If it doesn't require the premium, save your 10 cents a gallon and go buy some bait. That's all I got to say about that.

[LMITOUT]

That's fine, but Yamaha says 87 octane is OK but not more than 10% ethanol. Well, if you don't want 10% ethanol you have to buy premium (with the non-oxy sticker on the pump) in THIS state.