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muz123

Running higher octane gas?

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muz123

I would like to try to put 93 in my 520 and see how much of a difference the Onan will perform from 87 i use all of the time. Will it affect anything? Or will it benefit? 

Thanks!

Dave

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WHNJ701

I use super in all my small engines, 

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ebinmaine

My understanding is that unless you have a high-compression engine you do not need to run anything higher than regular or mid grade.

Chemically speaking, octane does nothing to boost the performance of any given engine. It merely slows down the combustion process so that high compression engines don't spark knock.

 

I've spoken to lots of people over the years that swear by it. I've also spoken to lots of people over the years that swear at it.

 

20 or 30 years ago or whatever I do remember there being suppositions by  people on the open market that gasoline companies were trying as hard as they possibly could to focus on selling people high octane gasoline that they did not need so they would put a couple of detergent additives in it and say that it was better. They weren't lying. It just was not necessary for 99% of the cars on the road.

 

The biggest gain in performance is actually from running an ethanol free gasoline.

 

I do run 91 or 93 octane but in the interest of fairness, that is because it is the ONLY type of gasoline I can get in my area that is ethanol free.

 

I'm super curious to see what the experiences and answers are of the rest of us that will reply.

I'm looking forward to following along on this one.

 

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WHNJ701

the biggest benefit I found was since most of my tractors are limited use and run only a few times a year is that fuel holds up longer with the stability and they run alot smoother

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posifour11

I'm lucky enough to live near a "destination/recreation" lake, so I have ready access to real gas. I normally use a little seafoam in it anyway, but I'm testing startron to see how it does. 

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AMC RULES

:rolleyes: Been using it for the past year...

and have nothing but positive things to say about it. 

Much better than any of my Seafoam experience.  :handgestures-thumbsup:

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lynnmor

I think that ebinmaine is spot on with his comments.  Today gasoline is required to have the detergent additives regardless of octane rating.  Additives are another waste of money with the possible exception of a stabilizer for long term storage.  Adding an ounce or so of snake oil will not make that one gallon of ethanol go away when it is mixed with nine gallons of gasoline.  JMHO

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shallowwatersailor

In my new city, we have a Royal Mart that sells ethanol-free 87 octane. But their 93 octane is ethanol-free as well. My new Yamaha pressure washer calls for a minimum of 89 octane so I just popped for five gallons of the 93 octane.

 

I do use Marvel Mystery Oil and Stabil mixed in to all my fuel as well. I did use a bottle of StarTron for part of one season. Strange but I only had a problem once using those two additives with 10% ethanol fuel in eight years. It was with my Subaru-powered log splitter. It solidified in the shutoff valve and I needed to literally drill it out. The valve was a white metal casting instead of the usual plastic which I believe was the issue. My HF pressure washer always amazed me how it would start at the beginning of the season (without proper storage!) on the second pull. I do believe that the ethanol dissipates over winter.

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Sarge

Ethanol is an acid - it is great at attacking pot metal and aluminum-based castings like that valve. That and the damage it can do to an air-cooled engine's valves is amazing in a short time. Using 93 octane won't hurt it, as long as it's non-ethanol. Ethanol added 93 octane will be a better base fuel than the regular pump grade 87 octane, but that 10% dilution of ethanol is still damaging in the long term. Sticking to even lower grades of pure fuel is always the best route and they charge more because it's pure fuel, not some garbage that can be upgraded with ethanol. The worst example is what most people are running in the vehicles/equipment - standard pump grade 87 octane with 10% ethanol added - the base fuel you're buying is total garbage and the 10% additive is required just to get it to the 87 rating. Every person I run across putting that crap in a gas can for their mowers and other equipment gets an education on what they're buying - and the damage they are causing by doing so. I'm on a one-man mission to get the stuff banned if at all possible, I'm tired of fixing other people's engines and having my tax dollars prop up one Lobby that basically feeds a whole network of subsidized plant owners getting rich off our misery. We have 4 plants in my area, their owners are really enjoying the benefits of the destruction, and will lie in any way they can to continue that practice.

 

Not out to make it a political argument, but it needs to stop.

 

Sarge

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chip61

I am not a fan of ethanol at all and I wish it wasn't being shoved down our throats. I am lucky enough that I have several sources of ethanol free fuel. A friend of mine has a new Silverado that is rated for E85-it was cheaper so he decided to try it last week-he said the truck absolutely hated it-no power and fuel mileage was terrible. He said in his area (very rural) E85 is starting to pop up more and more but he won't be using it again. 

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AndyK149

Higher octane fuel shouldn't give you any benefit since the engine isn't designed to take advantage of it.  It would be great if we could get ethanol out of our fuels, as there are major disadvantages to it and no advantages.  I saw comments above recommending ethanol-free gas and those are great suggestions.  One other option is buying leaded AVGAS from a local airport.  It is a 100 octane, leaded fuel.  It will not deteriorate and your engine will benefit from the lead content.  The one major disadvantage is having trace amounts of lead coming out of your exhaust.  I'll leave that one up to you!

 

I race motorcycles and many of us use AVGAS as an alternative to racing fuels; sometimes it is half the price. 

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recklessridr

i have to fully agree with AndyK149.  it oo have been involved in motorcycle racing.  my old Norton Commando was built for   " regular "  gas. at the time was 96 motor octane, leaded.  dyno runs did prove that higher octane DOES NOT mean greater performance,  contrary to popular opinion .   the dyno DID show ,, after trying high octane race fuel,, that a reduction in octane can actually produce

more HP.

  alcohol fuels suck ! as all agree, the metallurgy of contemporary engines & carb bodies , don"t like the stuff.  i try to stay with 90 OCTANE, alcohol  free. your engine will run as designed on it.  it is what is available locally, stores better, & doesn't seem to gum up the works.   fuel stabilizer of your choice will certainly help,, however check you product closely.   one of the most common name brands out there states on the bottle :  6 MONTHS  MAX.  

  IMHO,, this is the way to go.  just don't try to stock up on fuel & keep it reasonably fresh,, fuel stabilizers optioned as necessary for your specific needs.

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Skipper

I do not get it. Why do you put cleaning agents in your gas on a regular basis, or add other additives?  A splash of two stroke oil does a perfect job at stabilizing gas, and it for sure ain't harming your engine, most likely the opposite. just my  :twocents-02cents:

 

And on the octane (for normal gas anyway) the only thing a higher octane does, is raise the pressure at which the gas will combust on its own without a spark, so to speak. So no, in these engines there is zero notable difference.

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DennisThornton

I recently read an article by one experienced in the gasoline industry and he said the only advantage to higher octane was it reduced or eliminated "knocking", though some did have more than required by law detergents. 

 

I run it only because I can find only high octane ethanol free gas.  Otherwise I'd be running Startron or at least some stabilizer. 

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WVHillbilly520H
On 6/21/2018 at 11:25 AM, chip61 said:

A friend of mine has a new Silverado that is rated for E85-it was cheaper so he decided to try it last week-he said the truck absolutely hated it-no power and fuel mileage was terrible. He said in his area (very rural) E85 is starting to pop up more and more but he won't be using it again. 

From my own personal experiences with my 2014 Silverado 5.3 FlexFuel, when I'm running E85 (on several different occasions) it's like giving it a "boost" in power actually better throttle response and passing/on ramp power the down side was going from my normal 19 mpg average to 15-16 mpg average, so either he got bad batch full of water in the storage tanks(which is a high possibility because ethanol "read alcohol" draws/absorbs water) or the fuel sensor didn't read the composition correctly, again only from my personal experiences with my truck and the E-85 available near me, but yes I won't even buy E-10 for my :wh: unless I plan on running through it all that day, like @shallowwatersailor refered to above I live in the same county he has moved to there is an abundance of "pure" gas stations and my go to is "Southern States" non ethanol in 87/89&93 octanes as well as 50 cetane off-road diesel for my eMax, and even with the pure fuels I still use Berryman B-12 in my gas  and Power Service for my diesel supplements , then my 78 Malibu with the highly modified 406 CI SBC with 10.5 CR I'll buy 5 gals of 110 octane racing fuel and mix in 5 gals of non ethanol 93 to keep that iron headed beast from detonating, as for octane rating for the Onans in the 520s 87 non ethanol is all you need , Jeff.

Edited by WVHillbilly520H
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The Tuul Crib

 Yeah ethanol is a no-no in my small engines. A lot less carbon build up with the better octane. And my Huskvarna weedeater won't run on anything less than 93 to 95 octane.

Edited by The Tool Crib
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AndyK149

To the post above, you should expect a big drop in fuel economy when running true E85 (85% ethanol).  Ethanol has much lower energy density and will give you bad fuel economy.  However, it is substantially cheaper by the gallon than normal pump gas, which is basically E10-E15.  

 

To the comment about high octane reducing knocking - yep - that's the purpose.  Knocking or pinging is pre-ignition (spark) detonation.  So, higher octane reduces the combustibility (raises the flash point) and avoids knocking.  This allows you to 1) run more advanced ignition timing, 2) run a higher compression ratio, or 3) run more boost for forced induction applications.  Many modern engine do one or more of these.

 

None of those are applicable to a 12hp Kohler.  In summary, run regular octane, avoid ethanol if you can.

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Racinbob

I started a thread a few months ago on octane. I had just purchased a Caterpillar generator and the owners manual specifically stated to use fuel with an octane rating UNDER 90. That struck me odd so I wanted to hear what the guys said. Here's the thread:

 

.

Interesting replies. The bottom line is that all I can get is 91 octane and I'm running it with no worries. :)

 

 

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johnnymag3

Star Tron is excellent,..................... Seafoam is Excellent,......................Stabil is excellent.............................Marvel Mystery Oil is excellent......................... and so is getting non-ethanol fuel here locally !!!  

 

  There is no need for higher octane fuel in a low compression engine, just a waste of money in my opinion.....and you all know that everyone has one of these 

The above additives have different uses, so choose the one to remedy your issues!!!

 

John

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AndyK149

The replies in the generator thread are confusing and mostly anecdotal.  People seem to jumble the effects of ethanol / non-ethanol and the effects of octane levels.  Ethanol causes problems that are not solved by increasing octane.  Wrong octane causes problems that are not solved by ethanol content.  I think we've learned:

 

- Ethanol content can cause problems in any carbureated, low compression engine.  Particularly if it sits for extended periods.

- High octane provides no benefit to low compression engines and does not increase the stability of fuel that contains ethanol.  So it's a bit of a waste on your WH

- This is America, if you want to spend money on high octane and it makes you feel better, go ahead!

 

Here is a site to look for ethanol free gas in your area: www.pure-gas.org

 

 

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johnnymag3

Well said Andy... !!!!!

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EricF

Another conundrum with fuels and engine performance vs. manufacturer recommendations is due to emissions ratings of modern small engines.

 

Without any catalyst exhaust systems (yet?) they're dependent on narrow ranges of valve timing, spark temperature and carburetor characteristics to get the emissions to meet specs, and they do that based on whatever pump-grade gas is specced in the manual. So if they spec a requirement for nothing higher than 87-octane pump gas, it's probably because the burn characteristics of higher octane fuel throws the emissions out of whack, given the rest of the engine's operating behavior. Not that it matters in getting the grass mowed, or even much in the overall life and running characteristics of the engine. It's mostly about meeting emissions specs.

 

There are other things that octane rating can affect, though. Octane rating affects the speed at which the fuel/air mixture burns. High-octane fuel delivers a short, hot burst later in the combustion cycle. Lower octanes deliver a slower, gentler (relatively) combustion which starts earlier and lasts longer through the piston stroke. (This is why burned exhaust valves can result from running lower-octane fuel in high-compression engines -- the fuel may still be burning when the exhaust valve opens.) Combustion characteristics can also affect cylinder temperatures, which is is a concern with any engine, but can be particularly important on small air-cooled engines. High octane fuels are often said to give cooler engine temps because the fuel spray initially cools the combustion chamber slightly, then combustion gets over and done quickly, leaving the exhaust cycle to fully scavenge the heat. Lower-octane fuels may result in more heat soak of the combustion chamber and cylinder since the duration of the combustion is longer. Theoretically, then, high-octane fuel is well-suited for air-cooled engines as long as there's nothing funny going on with the valve timing that would cause incomplete burning with high-octane gas.

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Digger 66
On 6/21/2018 at 10:20 AM, Sarge said:

Ethanol is an acid

 

 Really ?

I love learning stuff on this forum !

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lynnmor

Any difference in the burning speed of various gasolines, is pretty much meaningless for our 3600 RPM tractors.  Studies have been done and there are mixed results with nothing that will matter for our purposes.  JMHO, but octane matters little for these engines, but ethanol content is a different matter.

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BOB ELLISON

Well I know first hand that ethanol is not good for these small engines. After sitting for 3 or 4 months my Lawn ranger would not start  so I pulled the carb off and this is what I  found. I now buy non ethanol gas for all my small engines. I still use seafoam and MMO as well.

20171025_141547.jpg

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