gade600sdi

I am ready to run my new 26GX. I live in Pennsylvania and flying on pretty flat land, maybe 400-600 above sea level. Here are the fuel choices I readilly have available to me:

1. Pump gas 93 octane (R+M/2)with 10% ethanol added
2. Pump gas 89 octane (R+M/2) pure gasoline with no ethanol added

I want to make sure I have enough octane so I do not detonate this $450 motor so for that reason I would use the 93 octane. On the other hand, I have been told by some to not use regular car gas because the added ethanol can cause problems. I also have been told that ethanol will ruin the gaskets in the walbro carburator because the alcohol over time will eat them up.

I have also been told that is a myth about the Walbro and that was true many years ago but for several years now the new walbro gaskets will stand up to Ethanol.

So I would like some intelligent advice on which way to go and adressing the ethanol problem that is now in so many states.

Thanks in advance for the help.

HunkaJunk

I run 85 octane with 10% ethenol in mine, never had any detonation problems and the carburetor parts should all be modern enough to handle the ethenol just fine.

Any corburetor Ihave seen that was manufactured within the last several years should handle 10% ethenol without problems.

All Day Dan

My Feedback: (5)

Send this to Horizonhobby.com to get the correct answer from the group who should be the most knowledgeable. Dan.

BobH

My Feedback: (2)

You are over thinking things lol... 85 Octane is just fine.. My bud's been using that in his for over 2 years with out issue.

tomservo9503

My Feedback: (1)

Even if it does eat away at the carb gaskets, a new gasket kit for one of these walbros is a whole 6 bucks. Even the old type gaskets will last a year or more running 10% ethanol through them. You really should replace them every year, anyways - I think most guys here use them where failure is a poor option at best, and the accelerator pump part tends to get saggy if it stays wet with gas all year.

pe reivers

Low octane fuel is not fine with that engine! Period. only premium fuel should be used, unless extra head shims are added.
You guys advocating low octane cheap stuff must be living at high altitudes, which makes you get away with it. Your usage however is not good general advice.

gade600sdi

Yes, what altitudes are you using 85? I havent even heard of 85 octane I have never seen less than 87 on any pump anywhere in the US. Not saying it doesnt exist, just that I haven;t seen it.

So, PE, are you ok with me using the 89 or the 93 with the ethanol? If shims, do I just buy the evolution head gasket and use an extra one or two of them (double up) to take the compression ratio down a little?

BobH

My Feedback: (2)

Sorry. it's 87 or low grade as its called.

I checked the Evolution info page.. no mention of Octane requirements.. only a 40:1 gas/oil ratio mix...If it were super critical I would think (hope) that that information would be posted there.

You can reduce your compression but to what end?

My friends engine runs GREAT!!!!! No Issues at all.. thats empirical data for the two years..

fyi the engine is located in Md.. not far from DC so no altitude issues..

pe reivers

89 is not premium I think? You still need extra shims when going that route.
Go for thefuel with ethanol. Engine and carb can cope with it..

arobatx

With the higher compression ratio engines I've had, they've all gotten premium grade gas...which around here is 93+ octane, I feed them the best I can get my hands on, that is readily available and not too far out of the way. Some manufacturers DO state that high octane fuel is required, or recommended.... 3W being one of them, and I believe they quote 98 octane

HunkaJunk

I'm in Denver, Wyoming also has 85 octane. but you are right KS has 87 most anywhere else gas grades start at 87. Also
premium is 91 octane here.

HunkaJunk

I do not give advice, recommendations, or endorsements on anything EVER! I just simply state what i do.

pe reivers

Which may not be the best thing. When you post like this, you make a statement, like it or not. Time will tell if what you do makes you get away with it.

HunkaJunk

GETAWAYWITHWHAT? RUNNINGMYENGINESON85 OCTANE? Hundreds of hours anc counting PAL!

pe reivers

If you can't win a debate, just shout harder.

HunkaJunk

what debate? You tell me I'm wrong, I don't care.

I will continue to rely on myself in all matters regarding this hobby. If you don't like what I do that is your problem.

gade600sdi

Thanks Pe for your intelligent well thought answers. I will take your advice as you seem to be very knowledgable. I agree, the Evolution manual says nothing on the fuel..terrible amount of information for a $450 motor at least they could give you a decent instruction manual. It says good quality unleaded, whatever that means. Don't think you could make it more vague if you tried. Also, they say 6.5 minimum volts on the ignition (IF YOU USE Battery Check) but it never says what the voltage range is if you do not use the battery test. NO mention zero nothing. So I got no clue if it will run on 6 volts, 5 volts, 4.8 volts or 4.4 volts, never says when the ignition goes down I guess your supposed to wreck your plane then test the voltage so you know when to stop.

Tired Old Man

My Feedback: (1)

Pe is an MVVS dealer in Europe and has been for a very long time. The Evolution gas engine line is an MVVS derivative. Pe has been working with these engines for many years and knows far more about them than anyone at Horizon ever will. For a two year owner of an engine to argue with a long time dealer and propulsion research engineer is ludircous. The two year owner only illustrates their ignorance of the products' limitations in the process. If one was to listen to Pe and follow his advice they would obtain better performance and greater longevity than they will otherwise.

If you ever hear something that sounds like gravel bouncing around in your engine you're in deep trouble. The problem is that often you don't get to hear that, and all that's evident is elevated nox levels in the exhaust gasses indicating that detonation is taking place. Without an exhaust gas analyzer and a good exhaust extraction tube that does not affect the exhaust resonance you will not find this out. Pre-ignition/detonation done often enough and the ring will just fall off the piston when a cylinder is removed. That fails to mention the pitted surface of the piston that will likely be evident as well. Bearings take a hell of a beating under those conditions and in extremly severe conditions rods get bent or broken. Rod ends become elongated, pounding the wrist pins in the piston. Yep, keep using that low octane gas in a higher compression engine. Doesn't make much sense to me but I suppose saving $0.10 / gallon is viewed as cost effective for some. Especially when this particular size engine will only burn about .6 kilograms of gas / hour at wide open throttle. A gallon of gas weighs 6 lbs. A kilo is 2.2 lbs. Prolly take a couple years to save a dollar at that rate, but hey, you saved a buck. Had to buy another engine but you're a dollar ahead somewhere

Higher compression engines require higher octane fuels. They WILL experience detonation otherwise. The 98 octane quoted by 3w applies to the European RON standards where the engines are made and assembled. That equates to about 91-95 octane here.

The vast majority of two stroke gas engines on the market using Walbro and Tillotsen carbs have components developed for ethanol laced gasoline. If it was made in the last 5 years or so it's good to go. If it's a very old engine, picking up a modern carb kit for $8.00 - $10.00 would provide the carb parts that are effective with ethanol blended gas. This information has been made public many, many times over the last few years and for some reason people don't pick up on it.

Don't make things more difficult than they need to be.

BobH

My Feedback: (2)

No one is arguing with any one here.. except .. maybe you. Im old and a professional in engines and engineering too. I only stated that 2 years of my friend running his engine without incidence was his experience. Take it for what its worth.