$1.49 Ethanol Tester - Available locally!

[JJuday]

Octane has nothing to do with the compresion ratios (pure octane has a rating of 100 and is a chemical in gasoline). It is a measure of a fuels resistance to compression induced ignition (pinging, dieseling) Fuel that is E10 and rated at 89 octane is still 89 octane its just that the base fuel without the ethanol started out at a lower octane rating.
Higher ethanol content means your engine needs more fuel to run properly but loses power due to ethanols lower energy content so you not only lose power but fuel efficiency. Ethanol also seperates out when it pulls in enough atmospheric moisture which leaves you stuck with a puddle of water in the bottom of your tank as well as a lower octane base stock.

Yes, octane has everything to do with compression ratios and how an engine will perform. You mean to tell me that running unleaded in a Diesel engine is not going to have a thing to do with how compressible that fuel is??? Or octane rating. The higher the octane the higher the compression ratio needs to be in order to get optimum combustion. There is a certian point when an engines performance is directly impacted by it's own compression ratio and how compressible it's fuel is. This is one reason why there are flex-fuel vehicles that run on E-85 and when they have no E-85 available they have to be run on premium. Anything much above E-10 will cause spark knock in regular engines, or imcomplete detonation, dieseling ect.


What I meant is that adding a 10% ratio of ethyl alcohol to gas can increase the octane rating by 2-3 points.

 

[angelo c]

You guys do realize that Ethanol, Gasahol, Ethyline, call it what you will has been around in some form or another since the 70's!?!?!

What proof is there to support "it burned up my engine" claims? If I didn't know any better I would assume that ...

If that was the case though why have we not heard about more people having car and truck engines seizing up?

Keep in mind that modern autos have electronicaly controlled ignition systems and variable valve timing technology to avoid this very situation. They can run on bat pi55 if filtered enough...hehe. the only way to vary the timing on a 2 cycle saw is to affect the mixture. apples and oranges comparison. Your $2.00 tester might be best used with a $1.00 screwdriver that keeps the mixture 4 stroking everytime you start the saw. The little Stihl orange screw driver should be part of the gas can IMO. One should not work w/o the other.

 

[JJuday]

Keep in mind that modern autos have electronicaly controlled ignition systems and variable valve timing technology to avoid this very situation. They can run on bat pi55 if filtered enough...hehe. the only way to vary the timing on a 2 cycle saw is to affect the mixture. apples and oranges comparison. Your $2.00 tester might be best used with a $1.00 screwdriver that keeps the mixture 4 stroking everytime you start the saw. The little Stihl orange screw driver should be part of the gas can IMO. One should not work w/o the other.

Engines that are designed to run on the higher concentrations of ethenol have higher compression ratios of engines that are not designed for that fuel.
E-85 will have around 100 to 105 octane ratings. Most flex-fuel engines require at the very least mid grade fuel if not E-85.
Octane = resistance to detonation or autoignition. By that definition if you were to run a low octane fuel in a high compression engine the result will be premature ignition. The oppostite would result in fuel partially igniting as in the case of running diesel fuel in a gas engine. High octane fuel reguires more cylinder preasure to properly combust if not it will have a dieseling effect. Low octane fuel in a engine with high compression ratios or cylinder preasures would result in premature ignition.

Does anyone out there run regular un-leaded in their saws? If not, why?

 

[ironman_gq]

Yes, octane has everything to do with compression ratios and how an engine will perform. You mean to tell me that running unleaded in a Diesel engine is not going to have a thing to do with how compressible that fuel is??? Or octane rating. The higher the octane the higher the compression ratio needs to be in order to get optimum combustion. There is a certian point when an engines performance is directly impacted by it's own compression ratio and how compressible it's fuel is. This is one reason why there are flex-fuel vehicles that run on E-85 and when they have no E-85 available they have to be run on premium. Anything much above E-10 will cause spark knock in regular engines, or imcomplete detonation, dieseling ect.


What I meant is that adding a 10% ratio of ethyl alcohol to gas can increase the octane rating by 2-3 points.

what I was saying is that the compression ratio of an engine has absolutely nothing to do with how octane of a fuel is measured. And it isn't the compression ratio of an engine that determines octane needs it is a factor of dynamic compression which is determined by cam or port timing and ignition which is why many of the new 4 stroke snowmobiles and bikes run well above 9-10:1 compression but can run on regular fuel but one of the older ones would be overheating. As far as putting gas in a diesel engine the diesel engine would run very
poorly if at all due to gas notbeing designed to auto ignite it would more than likely not run at all. Diesel in a gas engine on the othr hand would probably cause a catastrophic failure

 

[JJuday]

Ha hahaha! I don't have any engines that new fangled and fancy! Most of my stuff is older than me!

Most older engines cannot just change their preset compression ratios at a whim, there for if an engine has let's say 8-1 compressions ratio, it would make sense to say that a fuel with an octane rating of 100 would not completly combust in the cylinder. Likewise with fuels that have low octane ratings in higher comperssion engines....such as engines running from 10 to 12-1 compression ratios. In terms of performance at any level matching the fuel to the engine is critical.

Still.....you didn't answer my question.....do you run regular in your saw? If not, why?

 

[ironman_gq]

No I dont run regular becuase the only regular we have around here has ethanol and my stuff might sit for a while between uses and ethanol causes the fuel to go bad faster, absorbes water, eats the fuel lines, just not good. I use non-oxygenated premium and dont worry about it

 

[komatsuvarna]

As far as putting gas in a diesel engine the diesel engine would run very
poorly if at all due to gas notbeing designed to auto ignite it would more than likely not run at all. Diesel in a gas engine on the othr hand would probably cause a catastrophic failure[/QUOTE]

Diesel engine with gas, yeah itd run real poorly, After it pulled the studs out of the block and blew the head through the hood. Heat and extreme pressure is what makes a diesel fire. The injector is kinda like a spark plug too. When the piston comes up on the power stroke, Air is all it carrying with it. When it gets to the top(and under pressure) The injector squirts the diesel in the chamber in a fine mist. BOOM, back down. Diesels have high compression ratio. Most between 17:1 to 20:1. You squirt gas in a diesel engine it gonna Blow it to ####.

 

[ironman_gq]

Would barely run the gas wouldn't ignite properly. Old gas on the other hand due to octane degradation might run and I've heard of people running old diesels for short times on very stale gas where fresh stuff would barely pop.

 

[komatsuvarna]

Would barely run the gas wouldn't ignite properly. Old gas on the other hand due to octane degradation might run and I've heard of people running old diesels for short times on very stale gas where fresh stuff would barely pop.

Your correct, which you done knew. I didnt believe it at first until i done some research. I had a guy put gas in my diesel boring machine bout 10 year ago. He had it borrowed and i wasnt there. Anyway it quit on him. He figured out they gassed it and WE tore the engine down. The cylinders looked good but it bent A rod against the cylinder locking the engine from turning. We figured the gas explosion put too much pressure on the piston. I guess we were wrong though. My new guess is the cylinder must have got a lot of unburnt gas in it causing it to bend the rod? maybe the rod just decided to bend. Beats me! I learn something new everday. Ill rep you.