Tom, thank you for the kind words, interestingly enough in over forty five years of being a mechanic and being in the corn belt of America, I have found those who have a vested interest in farming in any way shape or form have a way of saying they never have any problems, number one reason?? it affects their wallet and they will go to the ends of the earth to protect it.
I work for farmers everyday at my shop, and here they have zero problem running non oxy in all of their small engines and equipment as they have had personal experiences running the Ecrap and down time is expensive when you need to get going.
I have even worked for folks who are so in denial that Ecrap is the problem that will make up every excuse in the book as to why stuff wont run even when I have a failed part in my hand showing it to them.
Enough of this, I can argue and argue with over a hundred thousand hours of experience and I will never get anywhere.
Grouse, you bet engines are sensitive to fuel, problem is most dont understand how an engine knows the difference, in todays modern engines the computer has an algorithm that uses the inputs from several sensors to determine this, the O2 sensor uses exhaust temperatures to tell the ECU whether the exhaust temps are rich or lean and it adjusts fuel ratios on the fly to correct whatever condition.
From there other sensors work with the O2 sensor to determine over the course of a tank of fuel used what fuel is in the tank, this is where short term and long term fuel trims come into play.
The algorithm isnt perfect as we still see several times per year where a car is running in a very rich condition, most often the owners have put in a tank of 85 percent ethanol and the computer gets stuck so to speak when E10 is put in the next tank and the computer hasnt had a chance to “relearn” the correct ratio and we have to reset it.
As far as octane, 91 ignites slower, it is done so to help prevent preignition, spark knock, detonation, too much timing, high compression etc.
Turbocharged engines are prone to this as are high output engines, remember the 6.0, 8.1, and many others that required it?
The issue with high octane as noted in John’s original question with the Optimax motors is that is a short stroke motor, how does that make a difference??
Simply put, with any short stroke motor, 91 octane is still burning at the bottom of the pistons stroke and especially on two strokes it will pollute the incoming air/fuel mix and it will soot the plugs in short order.
Using 87 octane, the the air/fuel charge is fairly well consumed and will not pollute the incoming air/fuel charge, there is bit of science to this as bore diameter, combustion chamber design, compression all have an effect.
The Optimax motor was designed to run on lower octane fuel as it took the length of the stroke into account, and IF YOU READ THE MANUAL WITH UNDERSTANDING it says,, a minimum of 87 octane is to be used, read that again, a minimum of 87 octane, 87 octane is not mandatory.
Now, back to Ecrap fuel with any outboard, whiny investors who thought they were not making enough money threw their weight around to force every modern motor to be able to use it, with the advent of better materials and tuning it is now possible, years ago the big three outboard manufactures ran engines to destruction to find out if they would live choking and gagging on corn gas.
They failed miserably, not because the parts were junk, if you read the reports the fuel performed almost identical between ecrap and non oxy, so why did they fail??
The exhaust temps were 300 degrees higher than non oxy fuel, this happened because oxygenated fuels have higher oxygen contents by their nature versus non oxy fuels.
Those high exhaust temps caused pistons to grow in size decreasing cylinder wall clearances which leads to scuffing, worse yet the higher temps cooked the oil to a point it no longer could lubricate anything, and when you get these things going on the piston gets above its melting point and you end up with a burnt piston and trashed motor, and remember, ecrap is a solvent and it will not blend with oil, instead it washes it off of moving parts.
The HPDI motors, do many of you realize that the engineers saw the issue with ecrap being a solvent?? yep, that is why oil is injected from the crankshaft side of the air chamber so that it does not have a chance to wash critical life giving oil off of the crankshaft, its bearings, the rod bearings, piston skirts, and cylinder walls.
On the intake stroke that oil is pulled through with the air and burnt when the fuel charge is burnt, no chance of losing lubrication before hand.
So better materials were engineered, better oils came to be through all of this which is a good thing as it does help a motor last longer in the hands of those who are too cheap to run good fuel and oil and throw in whatever abuse you can come up with.
My final thoughts on ecrap, yes, if you use it fresh everyday you can get away with it, but if you let it set you will have problems down the road, its too bad we have to buy another product to extend its life, think about that, more expense per gallon.
More acres that should not be farmed, more chemicals applied, fuel used to plant, spray, consume energy to create all of this stuff, more fuel used to harvest it, more fuel used to haul it to the ecrap plants, more fuel used to haul it away in trucks or via rail.
YEP, ecrap is wonderful stuff, its costs are so high in so many ways but its making folks rich…… and we pay for all of it.
And to top it off,,,, we pay to use something that is less efficient per gallon in the name of the environment, think about that we use more per tank,, wouldnt it be less pollutive to use less per tank??
Safer for the environment?? not if you add up everything I mentioned.
