Should We Be Compensating At The Pump For E10?

[jhoffman]

Got to thinking and doing a little reading since I have been having ignition issues. Basically due to the reduced rate of burn of ethenol vs strait gasolene Im wondering if I should step it up. The motor calls for 87, but that 87 was pre e10. With e10 in there 89 would be essentially like running 87. Right or wrong?

[Fishing Rhino]

I'd say no.  The owner's manuals for the vehicles and outboards I have owned tell you to run a certain octane rating.  They mention nothing about the ethanol blended fuels as pertains to octane rating. 

 

What they do recommend, particularly for outboards is the use of fuel treatments such as Stabil.  The reason being is that the blended fuels will degrade faster, and also cause more problems with fuel lines.

[jhoffman]

correct, which I do use also. ethenol however burns slower and doesnt produce as much energy as gasoline. hence 87 isnt 87 anymore or do they already compensate for it during blending?

[00 mod]

For the manufacturers to call it 87, it has to be 87 octane. 

 

Jeff

[Scott F]

Higher octane fuel just has more anti-knock compounds and is designed for high compression engines. It won't do a thing for engines that don't need it.

[jhoffman]

I understand high compression vs low compression and what the fuels do for it, most motors we run also dont have the ability to advance the timing as needed. OO my club had this same discussion at the dock last night and someone said that exact thing. What I was thinking however is that yes as you go up in octane traditionally it does burn slower which so does e10. 87 today is not the same 87 as when my motor was designed youre artificially raising the octane with the introduction of e10 which doesnt output the same amount of energy even with the increase in octane. We all know e10 also has water issues and breaks down much much quicker.

 

I was running 89 in mine, switched to 87 and my cold starts really changed big time, I personally am going back to 89. I cant see how this theory of mine is incorrect but it very well could be that it is incorrect.

[quanjig]

I read somewhere that mid grade fuels have less additives making it easier on outboards. Can't remember where I saw the article or even if its true but since I started going with the mid grade fuel, any fuel related issues have been few and far between.

[Fishing Rhino]

File this one under, "if memory serves".

 

Originally, there was only one grade of gasoline.  As engine compressions increased, the heat generated by compression became sufficient to cause combustion.  In other words, car engines would suffer the ravages of pre-ignition.  Merely retarding the timing would not prevent pre-ignition.  Octane levels were increased, to raise the temps at which the air fuel mixture would "ignite".

 

Those of us who hearken back to and before the late sixties, early seventies, remember when car engines used to "diesel".  If you've seen the movie "Vacation" you may recall the scene where the Family Truckster kept "running" clunking and knocking until it finally wheezed, and stopped long after the ignition had been turned off.  It was quite common in that era, particularly in the "lean burn" engines that Chrysler developed.

 

Adjusting octane content adjusts the ignition temp of the air fuel mix.

 

The last vehicle I ran high test gas in was my '66 GTO.

 

To my knowledge, which is admittedly limited, octane rating has nothing to do with the rate at which fuels degrade.  Back in the day, we used the term "stale gas" to denote fuel which had been hanging around and caused starting problems, be it in a lawnmower, outboard motor, or vehicle.

[Berudd]

For the manufacturers to call it 87, it has to be 87 octane. 

 

Jeff

87 is 87. If ethanol changed the octane rating then it would have a different rating. If your engine was built before ethanol was added to gas then it may cause you problems but not due to low octane per say.

[scrutch]

I've always ran premium in my outboard. I've been fortunate to not have any issues with my motor so far. (I'm trying to word this properly so as to not jinx myself!) My mechanic has made comments to me about how clean the inside of my motor is when he scopes the cylinders every fall. I put in all my small engines. Nothing gums up and gets hard to start. I'm pretty sure they call it premium gas because its better.

[Long Mike]

I run 87 octane with e10 in my Merc 150.  I treat the fuel religiously with StarTron.  The motor starts and runs flawlessly.  It would be very difficult for anyone to convince me to change the octane rating that my motor is rated for.

[KU_Bassmaster.]

Whether it is doing any good or not I only run, and go out of my way to do so, ethanol free gas in my outboard.  Ethanol free gas near you can be found at the sticky at the top of this section.

[tomustang]

I've always ran premium in my outboard. I've been fortunate to not have any issues with my motor so far. (I'm trying to word this properly so as to not jinx myself!) My mechanic has made comments to me about how clean the inside of my motor is when he scopes the cylinders every fall. I put in all my small engines. Nothing gums up and gets hard to start. I'm pretty sure they call it premium gas because its better.

They call it premium because its the octane's nickname, even then it spans from 91 to 93. It's made to react better for higher compressions, it'll still do its job for 87/89 rated combustion and you'd probably wouldn't even know the difference, but you should still stick to the factory recommendations

[ColdSVT]

I understand high compression vs low compression and what the fuels do for it, most motors we run also dont have the ability to advance the timing as needed. OO my club had this same discussion at the dock last night and someone said that exact thing. What I was thinking however is that yes as you go up in octane traditionally it does burn slower which so does e10. 87 today is not the same 87 as when my motor was designed youre artificially raising the octane with the introduction of e10 which doesnt output the same amount of energy even with the increase in octane. We all know e10 also has water issues and breaks down much much quicker.

I was running 89 in mine, switched to 87 and my cold starts really changed big time, I personally am going back to 89. I cant see how this theory of mine is incorrect but it very well could be that it is incorrect.

e10 doesnt artificially raise octane...it DOES raise the octane...very minimally though. e10 87 is more like 87.6 lol

however, E85 for example is 114octane

E85 is getting pretty popular in the drag racing community because you can really lay the timing to it. the down fall is having to redo yoir fuel system for way more volume and corrosion proofing

[LTownFisher764]

I am in no way a marine mechanic but I am a gas/diesel tech. The octane rating is the ability of the fuel to resist knock or pre-ignition. That is all. It has nothing to do with burn rate. That is what ignition advance is for. If it takes x amount of seconds to completely burn a cylinder of air and fuel then you would need to start the burn earlier when the engine is at higher RPM since the engine is moving faster therefore less time to go through a cycle. Gasoline, diesel, ethanol, methanol and other fuels all have different burn rates and fuel requirements to be properly burned in an engine. Again I have no experience working on any type of marine engine but with fuel injection and computers. Almost all engine parameters are monitored and some can be adjusted to be able to keep the engine safe. Whether that needs to be to add or subtract the amount of fuel being injected into the engine or to advance or retard ignition advance. In the days of carbs and distributors you would do this mechanically. With the introduction to e10 gasoline the requirements of the fuel are slightly higher than of 100% gasoline. For instance for 100% gasoline the stoichometric value is 14.7/1 air fuel ratio. Typically with e10 fuels you are looking some where in the range of 14.3/1 air fuel ratio. With that said if you engine is unable to make the adjustments needed for the extra fuel then the engine would be in a lean condition and could potentially see some kind of pre-iginition. With computers it will monitor pre-ignition and measure it as knock and retard the ignition if it senses any knock. Typically in the automotive field you really couldn't hurt an engine by putting in premium when it calls for regular. Usually fuel recomendations  from the manufacturers are a minimum.  I hope this sheds some light on the op's questions.

[scrutch]

Without fail, every engine that I've ran in the last 20 years runs better, cleaner, and produces more power on premium fuel.

And that's about all I gotta say bout that...

[PotomacBassin]

Why do people ask questions on here, but then refuse to consider other's advise by telling everyone that responds that they're wrong. 

[jhoffman]

Thanks to e10, I had to order a new fuel pump rebuild kit yesterday because it ate my check valves.

[jhoffman]

I am in no way a marine mechanic but I am a gas/diesel tech. The octane rating is the ability of the fuel to resist knock or pre-ignition. That is all. It has nothing to do with burn rate. That is what ignition advance is for. If it takes x amount of seconds to completely burn a cylinder of air and fuel then you would need to start the burn earlier when the engine is at higher RPM since the engine is moving faster therefore less time to go through a cycle. Gasoline, diesel, ethanol, methanol and other fuels all have different burn rates and fuel requirements to be properly burned in an engine. Again I have no experience working on any type of marine engine but with fuel injection and computers. Almost all engine parameters are monitored and some can be adjusted to be able to keep the engine safe. Whether that needs to be to add or subtract the amount of fuel being injected into the engine or to advance or retard ignition advance. In the days of carbs and distributors you would do this mechanically. With the introduction to e10 gasoline the requirements of the fuel are slightly higher than of 100% gasoline. For instance for 100% gasoline the stoichometric value is 14.7/1 air fuel ratio. Typically with e10 fuels you are looking some where in the range of 14.3/1 air fuel ratio. With that said if you engine is unable to make the adjustments needed for the extra fuel then the engine would be in a lean condition and could potentially see some kind of pre-iginition. With computers it will monitor pre-ignition and measure it as knock and retard the ignition if it senses any knock. Typically in the automotive field you really couldn't hurt an engine by putting in premium when it calls for regular. Usually fuel recomendations  from the manufacturers are a minimum.  I hope this sheds some light on the op's questions.

 

My engine is a 92, carbed none the less and doesnt have the ability to compensate for it on the fly. I know my 08 cbr600rr could compensate for running 87 even though it was a high compression, I personally never took it below 93 and from selling ducati had shell gas on the brain.

[wnybassman]

We had a highly regarded marine tech show up at our last club meeting to discuss routine boat maintenance.  A lot of the discussion was about E10 fuel.   He said that E10 loses its octane at a greater pace than non-ethynol gas.  Most vehicles are not a problem because you go through it fast enough.  Boats are generally different, and fuel sits for more time before getting burned.  Anyway, he said that 87 octane you put in today may be 84 or 85 octane after 30 days.  He highly recommends at least 89 so when it loses a little octane it is back where it should be to start with.

 

He was also not a big fan of fuel treatments, and said the "cocktails" are the worse.   His repair records have shown about the same rate of failure for those who add nothing to fuel to those who add something.  The cocktails have the highest rate of failure, and he contributes that the additives having a fair amount of alcohol in them, and that is added to fuel with ethynol already in it compounding the problem.   He basically said stuff will happen regardless of whether you add anything or not.  I still add what I have added over the last several years, just because it still makes me feel good I guess.  I know people that use "cocktails" with good results and I also know people that add nothing and have had no problems.  I also know people that have had problems doing all three things, so maybe he is right to some degree.

 

I know I had to take everything with a grain of salt with him being a marine shop owner and he may just want our business, but it didn't seem like that was the case.    lol