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Tired of fighting the ethanol deal when I am not near the real stuff. Does aviation fuel degrade as fast as regular automotive gasoline?

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My old KTM 350exc loved avgas. 

Yes, with proper storage it lasts a really long time. It does contain a noteworthy amount of lead, so don't huff the exhaust fumes. 

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To answer your question, no, avgas doesn't degrade as fast as 85/87/89/91 E10 fuels.

The "right" fuel is 91 non-ethanol. 

Avgas is higher octane (which is just a measure of the fuel's resistance to pre-ignition), but it's formulated for a much slower burn rate than 91E0.  At higher RPMs that snowmobiles and motorcycles are designed to run at, you won't get the performance out of avgas that you will from a lower-octane fuel designed with a burn rate at snowmobile/motorcycle RPM's.

 

Stock up on 91E0 (stop by a marina or check on puregas.org for locations near you) and store it properly, it'll last a summer pretty easily. 

IMG_20151211_234053173-L.jpg

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4 hours ago, YHGEORGE said:

Tired of fighting the ethanol deal when I am not near the real stuff. Does aviation fuel degrade as fast as regular automotive gasoline?

It definitely last longer than pump gas.  If you are looking for a long shelf life of any fuel then the way you store your fuel is most important.  Vp racing told me to make sure the can is not on the floor, it needs to be propped up on wood so air can flow under the can and if possible to use a metal can because they store the fuel better and make sure the temperature doesn't get super cold or hot.

Edited by 96motorhead
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Just buy ethanol free. And only what you're going to use. I don't know why people "store" 5 gallons of gas.

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3 hours ago, SnowMule said:

To answer your question, no, avgas doesn't degrade as fast as 85/87/89/91 E10 fuels.

The "right" fuel is 91 non-ethanol. 

Avgas is higher octane (which is just a measure of the fuel's resistance to pre-ignition), but it's formulated for a much slower burn rate than 91E0.  At higher RPMs that snowmobiles and motorcycles are designed to run at, you won't get the performance out of avgas that you will from a lower-octane fuel designed with a burn rate at snowmobile/motorcycle RPM's.

 

Stock up on 91E0 (stop by a marina or check on puregas.org for locations near you) and store it properly, it'll last a summer pretty easily. 

IMG_20151211_234053173-L.jpg

This is a Internet rumor. Gas doesn't care about RPM, and you will never find any valid information to support that claim. 

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8 hours ago, YHGEORGE said:

Tired of fighting the ethanol deal when I am not near the real stuff. Does aviation fuel degrade as fast as regular automotive gasoline?

nope it lasts much better, cant be having your airplane carb clogging up because it was stored for the winter

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On 4/13/2017 at 11:54 PM, 69fastback said:

This is a Internet rumor. Gas doesn't care about RPM, and you will never find any valid information to support that claim. 

You couldn't be more wrong. Different fuel formulations can have wildly different flame propagation rates, and higher rpm engines need fuels with higher propagation rates to allow complete combustion.

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23 minutes ago, The Spanky said:

You couldn't be more wrong. Different fuel formulations can have wildly different flame propagation rates, and higher rpm engines need fuels with higher propagation rates to allow complete combustion.

What you say is partially correct, but unfortunately holds no merit in aviation fuel.   To say you won't get the performance out of Avgas, like you would out of a lower octane fuel, designed to run at a higher RPM, is wrong. Avgas isn't like that, and I sold Avgas, viewed and approved the data sheets, and burned it in a variety of vehicles, ranging from airplanes, to motorcycles, to a 9 second street/strip car. As I said, That's something people say on the internet, with no data to back it up. 

 

Now on another note, if your engine doesn't require the higher octane, it can degrade performance, but that has nothing to do with Avgas. That has to do with running a higher octane than your engine requires. 

Edited by 69fastback

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I'm onboard with 69fastback. Fuel doesn't care about RPM. Compression is what matters. Octane ratings describe a fuel's resistance to preignition (ignituon by comptessuon, rather than spark). When preignition occurs, due to lower octane levels, you get a knock because essentially the fuel/air mixture is igniting twice. Once by compression, and the remainder by your spark plug.

As for storage, the best route to go is ethanol free fuel (91E0). The sticker on your bike probably recommends 91 octane, like mine, because it is a high compression engine. Ethanol accelerates the degradation of fuel, so fuel w/o ethanol is predisposed to last a bit longer. Storage is key, however.

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20 minutes ago, 69fastback said:

What you say is partially correct, but unfortunately holds no merit in aviation fuel.   To say you won't get the performance out of Avgas, like you would out of a lower octane fuel, designed to run at a lower RPM, is wrong. Avgas isn't like that, and I sold Avgas, viewed and approved the data sheets, and burned it in a variety of vehicles, ranging from airplanes, to motorcycles, to a 9 second street/strip car. As I said, That's something people say on the internet, with no data to back it up. 

 

Now on another note, if your engine doesn't require the higher octane, it can degrade performance, but that has nothing to do with Avgas. That has to do with running a higher octane than your engine requires. 

This post shows how little you actually know about fuels.

 

I'll get into more detail later when I'm not on a phone, but we'll start with, octane rating has ZERO to do with how much power a fuel will produce in a given engine. You talk about internet myths, well that's one of the biggest ones there is. The amount of power a fuel can produce in a given engine is determined strictly by the btu content of the fuel. If you have two different fuel formulations with the same octane rating but one has s higher btu content, the higher btu content fuel will produce more power. Or if you have two fuels, one with a higher octane rating and a higher btu content, it will produce more power than a fuel with a lower octane rating and a lower btu content every single time.

Octane rating is nothing more than a measurement of a fuel's resistance to auto-ignition. It has zero to do with how fast the fuel burns, how much power it produces, flame temps, or anything else other than auto-ignition prevention.

Edited by The Spanky
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8 minutes ago, SpyderXLT said:

I'm onboard with 69fastback. Fuel doesn't care about RPM. Compression is what matters. Octane ratings describe a fuel's resistance to preignition (ignituon by comptessuon, rather than spark). When preignition occurs, due to lower octane levels, you get a knock because essentially the fuel/air mixture is igniting twice. Once by compression, and the remainder by your spark plug.

As for storage, the best route to go is ethanol free fuel (91E0). The sticker on your bike probably recommends 91 octane, like mine, because it is a high compression engine. Ethanol accelerates the degradation of fuel, so fuel w/o ethanol is predisposed to last a bit longer. Storage is key, however.

Octane rating has nothing whatsoever to do with pre-ignition. Pre-ignition and auto-ignition (detonation) are two completely different phenomenon.

 

Again, I'll go into more detail when I get on the computer. Off to get a haircut now. :thumbsup:

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12 minutes ago, The Spanky said:

This post shows how little you actually know about fuels.

 

I'll get into more detail later when I'm not on a phone, but we'll start with, octane rating has ZERO to do with how much power a fuel will produce in a given engine. That is determined strictly by the btu content of the fuel. If you have two different fuel formulations with the same octane rating but one has s higher btu content, the higher btu content fuel will produce more power. Or if you have two fuels, one with a higher octane rating and a higher btu content, it will produce more power than a fuel with a lower octane rating and a lower btu content every single time.

Octane rating is nothing more than a measurement of a fuel's resistance to auto-ignition. It has zero to do with how fast the fuel burns, how much power it produces, flame temps, or anything else other than auto-ignition prevention.

Are you arguing with yourself?  Where do I mention anything about any of that?  I was in the fuel buisness with for half my life, so I'll let your uniformed comment slide. 

 

Let me put this in a practical, real world example for you. I have a car that I race. Real world results, that show real world power, and not some Internet hearsay debate. On Avgas, it averages about 139 mph trap speed, and on VP110 it averages about 139 mph trap speed. This motor gets shifted at 7200 rpms, more than double what a horizontally opposed aircraft engine is meant to turn. So, on a fuel that's designed for a racing application, it made no more power than it did on this fuel that's not meant for high rpm engines. 

 

Im perfectly aware of the effects of octane ratings and engines, and once again, your partially correct, because too high of a octane CAN and WILL degrade performance, as not enough compression will make it hard for that cylinder to combust it clean and compete, so to say it has zero to do with it is incorrect. BTU rating was irrelevant to what I said. 

 

 

Back to avgas.....real world results, it produced the same power, in a "high rpm" engine. How's that possible???  Oh I know the answer, and it's not internet science and bench racing.   

Edited by 69fastback
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2 hours ago, 69fastback said:

Are you arguing with yourself?  Where do I mention anything about any of that?  I was in the fuel buisness with for half my life, so I'll let your uniformed comment slide. 

 

Let me put this in a practical, real world example for you. I have a car that I race. Real world results, that show real world power, and not some Internet hearsay debate. On Avgas, it averages about 139 mph trap speed, and on VP110 it averages about 139 mph trap speed. This motor gets shifted at 7200 rpms, more than double what a horizontally opposed aircraft engine is meant to turn. So, on a fuel that's designed for a racing application, it made no more power than it did on this fuel that's not meant for high rpm engines. 

 

Im perfectly aware of the effects of octane ratings and engines, and once again, your partially correct, because too high of a octane CAN and WILL degrade performance, as not enough compression will make it hard for that cylinder to combust it clean and compete, so to say it has zero to do with it is incorrect. BTU rating was irrelevant to what I said. 

 

 

Back to avgas.....real world results, it produced the same power, in a "high rpm" engine. How's that possible???  Oh I know the answer, and it's not internet science and bench racing.   

First, I apologise for my insult, it was uncalled for and does not make for a healthy discussion. I hope you can overlook it.

As to "where did I mention that", it was you that brought up the subject of octane rating versus power production.

I am not arguing that Avgas can make the same power as pump gas in our engines, it was not I that made that statement. The formulative differences between pump gas and Avgas aren't so different that the burn rates are drastically different, and our engines tend to have enough ignition advance and well designed combustion chambers that the negligible differences in burn rates are irrelevant. In Avgas, formulaters focus more on keeping RVP lower to maintain fuel stability under lower atmospheric pressures and high temps to prevent vapor lock. But I'm sure you know this already.

My argument is about your blanket statement that higher octane makes less power. This is a widely believed misconception, fomented by people that don't know what they're talking about spewing nonsense on the internet, and people that are genuinely trying to learn believe this BS because they don't know any better and so become ill-informed.

Now you are partially correct in that, some exotic fuel blends that have very high octane ratings will make less power in "normal" engines, engines that aren't tuned for the qualities and properties of these fuels. But you're talking expensive exotic fuels that no one in our sport is ever going to run in a dirt bike engine, and again, the primary culprit is fuel chemistry, not octane rating. 

 

My point is, so many people believe the internet myth that if you run 93 octane pump gas in your car that's made for 87, or you run some VP C12 in your stock (but properly jetted for the fuel) motocross bike it will make less power, and this simply isn't true. The fuels that are generally run in our cars and bikes are chemically very similar with essentially identical btu content, and the octane rating is not going to affect the power generated.

For our engines, if people would take the time to tune their jetting and ignition advance properly for it, will make more power and have better throttle response with a fuel like VP C12 than they ever will with any of the garbage that comes out of gas pumps.

Avgas has the benefit of being much more consistent from batch to batch than the ever-changing pump swill, so jettting is an easier task.

Choosing a proper fuel for our engines is much more about chemistry than octane ratings. Vapor curves and RVP are much more important, but too many people focus on octane rating because they don't know any better.

Edited by The Spanky
Autocorrect stupidity...

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Now I can get on board with all that, and yes, i shouldn't have made a blanket statement such as I did, because you're right, it's. It always the case. On the flip side, people who think they can always make more power with more octane are also incorrect. The real story is it depends on the engine, combustion chamber effiencey, flame front, Ect, and also the particular fuel properties. 

 

In this case, I've heard many people talk about 100LL not being for high RPM use, but the fact is that it's just fine to run it in your bike/car, if you're jetted properly, and your engine will perform just fine. Also, as you stated, it's very consistent. 

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I've used it for many years and currently still do in my 2006 slightly modded 125 and 1985 125 also.Very good results in both.Harry Klemm recommend I use it it a big bore 760 Yamaha Raider motor he built for me.Again very good results.One I've jetted it doesn't very in performing other than air mixture adjustment.

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43 minutes ago, 69fastback said:

Now I can get on board with all that, and yes, i shouldn't have made a blanket statement such as I did, because you're right, it's. It always the case. On the flip side, people who think they can always make more power with more octane are also incorrect. The real story is it depends on the engine, combustion chamber effiencey, flame front, Ect, and also the particular fuel properties. 

 

In this case, I've heard many people talk about 100LL not being for high RPM use, but the fact is that it's just fine to run it in your bike/car, if you're jetted properly, and your engine will perform just fine. Also, as you stated, it's very consistent. 

Agreed to all. :thumbsup:

 

I have run LL100 before, and my only complaint with it is that it's high aromatics content tends to make for slightly soft throttle response when compared to something like C12. But if you have a detonation issue and a proper race fuel is out of your budget, less than perfect throttle response is a small price to pay to not have a detonation-induced engine failure. Avgas isn't a replacement for a properly selected and tuned for race fuel, but it is good enough in our engines.

It is worth noting that LL100 is NOT a particularly high octane fuel. It had a MON rating of 96 and RON of 106, giving it a (R+M/2) of 100 octane.

 

The biggest problem with LL100 in our engines is it's high 90% point of 275°. That's much higher than a proper race fuel like C12 ( ~220°), but still much better than the 375°( or higher) of pump fuel.

Edited by The Spanky

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Seems like a lot of hassle to get away from E10 pump gas, which I must be the only one having zero issues with.

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