Ethanol = Less/More/Same power?

Curious to know how ethanol gasoline and all the additives effect power.

Lets pretend that we have 92 octane gasoline.

One brand is pure gasoline, the other is the standard 10/6% ethonal blend with whatever additives that are found at the pumps.

IF you put this into say a yz450 or a 250 two stroke and ran it on the dyno comparing one bike using two different gasolines, would there be a power difference?

I think I'm trying to find out if ethanol saves on smog at the cost of power?

Does ethanol have any kind of anti knock capabilities in OUR dirt bike engines?

I searched and couldn't find an answer to this, lots of threads about ethonal and how it sucks, attracts water, how to remove, etc, but nothing comparing if it effects power to regular gasoline.

Pretty well known fact that ethanol doped fuel produces less energy when burned compared to standard gasoline. Give Google another try :ride:

Pretty well known fact that ethanol doped fuel produces less energy when burned compared to standard gasoline. Give Google another try :ride:

yes they contain less energy for the same amount of fuel, but that balnces out by being able to burn more ethanol to a given part of air.

pure ethanol with produce alot mroe power then pure gasoline because ethanol has a much higher octane rating, and so the engine can be made with a much higher comrpession ratio but the engine will also use a lot more fuel the if it were to run on gasoline, same octane (say 92) they will both make similar power, but you'll have to rejet with the ethanol fuel (richer, so it will sue more fuel).

however most of the seals in the fuel systems on bikes are NOT compatible with ethanol fuels, and so should be avoided like the plauge (not to mention the jetting headaches of running ethanol fuel)

As a general starting point when we ran Methanol, we would double our jet size and work from there. And yes, it would turn rubber to stone.

As a general starting point when we ran Methanol, we would double our jet size and work from there. And yes, it would turn rubber to stone.

I still have an old Lectron set up for methanol that I used on a '93 KX250. Ran great on top but dealing with the methanol proved to be a head ache. I was constantly testing the specific gravity of the fuel for water contamination and had to have premixed gasoline in addition to the methanol for pickling the engine every time it was used.

Are gas stations required to disclose this information (use of 10% ethanol)? Do you know if this applies to gas stations in NC?

yes they contain less energy for the same amount of fuel, but that balnces out by being able to burn more ethanol to a given part of air.

pure ethanol with produce alot mroe power then pure gasoline because ethanol has a much higher octane rating, and so the engine can be made with a much higher comrpession ratio but the engine will also use a lot more fuel the if it were to run on gasoline, same octane (say 92) they will both make similar power, but you'll have to rejet with the ethanol fuel (richer, so it will sue more fuel).

however most of the seals in the fuel systems on bikes are NOT compatible with ethanol fuels, and so should be avoided like the plauge (not to mention the jetting headaches of running ethanol fuel)

Fuel is a very interesting subject and probably more misunderstood than oils, if that is possible. Here are a couple of FYI facts and helps me understand the posting above.

The octane rating is a measure of the resistance of petrol and other fuels to autoignition in spark-ignition internal combustion engines. (WIKI)

Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. (WIKI) So what does this mean in laymans terms? Higher octane ratings simply mean the explosion of fuel is controlled in a more precise manner and this in turn makes an engine more efficient for the simple reason that the combustion stroke happens correctly.

There is a lot more to be said about ethanol to include that a true ethanol based engine needs a lot more compression to run efficiently ...much more than a gasoline based engine.

From this limited knowledge base, yep, ethanol waters down gas for several reasons. And yep, the feds have their hands in on this. Pure gasoline is probably the best you can get for our engines. I'm not 100% sure how an octane rating applies here as all we need is a correct explosion of the gasoline at the correct instant.

Probably, if you ran 'regular' gas in your bike and it did not ping (meaning the combustion stroke happened correctly), the higher octane stuff may not needed. It is a little confusing and a little difficult to changes ones' thinking after so many years of being in the dark. The naming convention for the different gases may be another marketing tool pointed at the consumer same as the term 'synthetic' when used with oils.

Myself, I can't afford gas at the prices it when up to in the early \ mid 2000's and continues at today. Yet, I must buy it. What does this mean? We are all having our way of life dictated by oil prices. I'm gonna try the gas with a lower combustible rating and see how my bike runs and maybe do some blending at the gas pump in the future :ride:

Edited by ray_ray

I'm pretty much trying to find out if it's better to run leaded 110 even if your engine only calls for 92 because it's pure and has no ethenol.

Regardless of how ethenol affects rubber seals in the carb.

If the 92 octane is ethanol free, no it is not better. 110 octane fuel in an engine that requires 92 octane is a waste of money and fuel economy. Unless you have a freakishly high comression ratio that you experience detonation, preignition, pinging, etc. with, you do not need this high of an octane rating. As you raise the octane rating you make the fuel more difficult to ignite in the cylinder. Higher compression also compounds that. That is why high performance vehicles such as drag cars will have ignition systems that put out much more energy (spark) to the spark plugs to fire that cylinder and get a complete burn of the fuel. If you ever been close to a Top Fuel dragster of Funny Car, often times you will see raw fuel (methanol and nitromethane) blowing and dripping from the exhaust headers because it hasn't been burned in the combustion chamber. The magnetos on the car are putting out just barely enough energy at idle to sustain combustion.

If the 92 octane is ethanol free, no it is not better. 110 octane fuel in an engine that requires 92 octane is a waste of money and fuel economy. Unless you have a freakishly high comression ratio that you experience detonation, preignition, pinging, etc. with, you do not need this high of an octane rating. As you raise the octane rating you make the fuel more difficult to ignite in the cylinder. Higher compression also compounds that. That is why high performance vehicles such as drag cars will have ignition systems that put out much more energy (spark) to the spark plugs to fire that cylinder and get a complete burn of the fuel. If you ever been close to a Top Fuel dragster of Funny Car, often times you will see raw fuel (methanol and nitromethane) blowing and dripping from the exhaust headers because it hasn't been burned in the combustion chamber. The magnetos on the car are putting out just barely enough energy at idle to sustain combustion.

This concept I completely understand, I'm not talking about resistance to detonation (octane ratings).

I'm talking about pure gasoline versus ethonal gasoline, throw a bike on a dyno running one and the other, is there a power difference.

These bikes in stock form (mine at least) only requires 92 octane, I was just using 92 octane as an example of a baseline. As far as I know, you cannot find 92 octane WITHOUT ethenol where I live, it doesn't exist. You can however find regular high octane gasoline without ethenol, but again I'm not talking about anti knock index here, I'm talking about pure gas versus gas mixed with ethenol and a power difference.

So for those that don't understand, lets just pretend then 92 octane with 6-10% ethenol versus 92 Octane without ethenol and dyno results.

Is there a difference?

I would like to know too, because I can get AV gas for basically the same price as the ethanol shit at the pump

I had to clean tanks this year, ethanol turned to jello, I really dont want to run ethanol anymore

I'm pretty much trying to find out if it's better to run leaded 110 even if your engine only calls for 92 because it's pure and has no ethenol.

Regardless of how ethenol affects rubber seals in the carb.

If we are just talking about leaded 110 vs. unleaded 92 vs. Ethanol, I personally would take the time to mix 1 gallon of 110 mixed with 4 gallons of 92 and jet for that, if you are going to burn it in a 2 stroke (they like lead in the gas).

If you are running this in a 4 stroke then I wouldn't even bother, I would just stick with pump 92. Consider running the 4 to 1 gallon mix only if you have a dyno available that you can use to nail down your jetting.

Ethanol (e85) does have a higher octane rating (about 100) and a few drag racers are starting to play with it with good results. The problem is that it's not a very consistant blend. e85 is suppose to have 85% alcohol, but sometimes it may be 80% or even lower. It's to the point where anyone that's racing with the stuff will buy an analyzer and test the fuel just so they know what they are getting, and then jet accordingly.

More specific advise can be had if you post this in the jetting section.

And for what it's worth when I was racing circle track (cars on a half mile asphalt) the rule of thumb with burning straight alcohol was that it gave you more torque, the same top end, you used it at twice the rate as gas, and it was very hard to jet (becuse you use so much).

This concept I completely understand, I'm not talking about resistance to detonation (octane ratings).

I'm talking about pure gasoline versus ethonal gasoline, throw a bike on a dyno running one and the other, is there a power difference.

These bikes in stock form (mine at least) only requires 92 octane, I was just using 92 octane as an example of a baseline. As far as I know, you cannot find 92 octane WITHOUT ethenol where I live, it doesn't exist. You can however find regular high octane gasoline without ethenol, but again I'm not talking about anti knock index here, I'm talking about pure gas versus gas mixed with ethenol and a power difference.

So for those that don't understand, lets just pretend then 92 octane with 6-10% ethanol versus 92 Octane without ethenol and dyno results.

Is there a difference?

First, I think this question has already been answered above but I'll try to provide some more facts here. Straight gas should be better and octane rating do not point to power output. So forget them. If the motor does not ping and knock...U have very good fuel detonation and this does point directly at power output.

If neither mixtures causes your engine to ping, some difference should be there but how much? From what I can deduce from all this reading is, if no ping happens, the fuel was ignited correctly and that is all we are looking for.

With that said ...There is ~10% of the fuel that is ethanol. In general, ethanol-only engines are tuned to give slightly better power and torque output than gasoline-powered engines. In flexible fuel vehicles, the lower compression ratio requires tunings that give the same output when using either gasoline or hydrated ethanol. For maximum use of ethanol's benefits, a much higher compression ratio should be used, which would render that engine unsuitable for gasoline use (WIKI)...Our flexible engines are not 100% designed for burning ethanol so some power should be lost here it would seem.

And I don't know jack about fuel ...I have just read all this over and over from the web and came up with all this ...some sort of self enlightening on fuel and octane and pinging. All this has been a big deal since Henry Ford made the model T and ran it off ethanol, which is nothing but PGA.

Here are couple more items on fuel I discovered that I thought were interesting:

1) Most fuel stations have two storage tanks (even those offering 3 or 4 octane levels), and you are given a mixture of the higher and lower octane fuel. Purchasing premium simply means more fuel from the higher octane tank. The detergents in the fuel are the same.

2) You only use dry gasoline by filling up early in the morning when the storage tanks are cool. Also ensure that the service station storage tank has not been refilled recently. Retailers are supposed to wait several hours before bringing a refilled tank online, to allow suspended undissolved water to settle out, but they do not always wait the full period. (This might explain why we get watered gas sometimes)

Edited by ray_ray

so nobody knows how leaded 110 will work compared to 92 ethanol?

The problem with ethanol is, it's lower on power, and it turns to jello in my garage, I guess the humidity is too high in there, the ethanol falls out of suspension and settles in the bottom of the tank like clear looking jello. If there's no performance hit, I can get aviation fuel for the same price as 93 pump with 10 % ethanol, I suspect I've gotten higher % ethanol because it should not fail that fast

so what is the verdict on STRAIGHT leaded AV fuel, the last thing I want to do is mix in ethanol with it, I might as well stick to pump gas.

so nobody knows how leaded 110 will work compared to 92 ethanol?

The problem with ethanol is, it's lower on power, and it turns to jello in my garage, I guess the humidity is too high in there, the ethanol falls out of suspension and settles in the bottom of the tank like clear looking jello. If there's no performance hit, I can get aviation fuel for the same price as 93 pump with 10 % ethanol, I suspect I've gotten higher % ethanol because it should not fail that fast

so what is the verdict on STRAIGHT leaded AV fuel, the last thing I want to do is mix in ethanol with it, I might as well stick to pump gas.

This thread has an article on avgas on page 2 and explains what this fuel should and should not do. And you can make up Ur own mind but no one would say add ethanol to it I would think..

http://www.thumpertalk.com/forum/showthread.php?t=866500&page=2

Gasoline is just gasoline ... and we have man induced variations ... but the purer the better and if it doesn't knock and ping when detonated in Ur engine , it is pure enough :ride: regardless of the magic octane rating that has nothing to do with power and only helps the detonation process and once the detonation process is correct, it ain't getting any better till you change the engine or its components, or change fuels ...

Edited by ray_ray
so what is the verdict on STRAIGHT leaded AV fuel, the last thing I want to do is mix in ethanol with it, I might as well stick to pump gas.

I run straight 100LL. It works great. Imagine if you took good, ethanol free 94 octane pump gas and added two grams of lead per gallon. That's essentially what 100LL is.

I run straight 100LL. It works great. Imagine if you took good, ethanol free 94 octane pump gas and added two grams of lead per gallon. That's essentially what 100LL is.

May i threadjack this thread a little and ask, what bike you run, motor mods you have done to it, and why you don't mix it 50/50, etc? I've been doing heavy research on the av100ll gas threads and have wanted to get some reasons why people do/don't mix it.

May i threadjack this thread a little and ask, what bike you run, motor mods you have done to it, and why you don't mix it 50/50, etc? I've been doing heavy research on the av100ll gas threads and have wanted to get some reasons why people do/don't mix it.

I run straight 100LL in a stock '08 CRF450, a '82 RM250 and '07 CRF150RB. I run it 100% because it runs great, it's got a little lead in it and it's ethanol free. It's only 75 cents more than pump so there's not much cost savings mixing them and mixing fuels is kind of a hassle.

May i threadjack this thread a little and ask, what bike you run, motor mods you have done to it, and why you don't mix it 50/50, etc? I've been doing heavy research on the av100ll gas threads and have wanted to get some reasons why people do/don't mix it.

I plan to start running 100LL, one reason is to be able to bump CR a touch. The reason I don't plan to mix with pump cat piss, is that (at least here) it is not very consistent, it changes thru the seasons. I want to get my jetting mapped out, and run a fuel that's more stable, and like Cam stated, the cost difference is minimal.

So for those that don't understand, lets just pretend then 92 octane with 6-10% ethenol versus 92 Octane without ethenol and dyno results.

Is there a difference?

The way I understand it is that an equivalent amount of ethanol has 2/3 the energy of gasoline.

At 10% ethanol blend like we get here in NY, that means that a gallon of blend would be 4% down on energy? I would imagine that there would be an equal 4% drop in power on the dyno.

All we get is 10% here in NY, and have for years, so I drop Sta-bil in it (it doesn't last as long as regular gas) and run it and never think anything about it.

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