® Some Thoughts About Pump Gasoline

Let's cut to the chase. The problem with gasoline isn't the oxygenates, and it isn't the octane, and it isn't presumed greedy oil companies making a lousy product. There is no lack of articles about gas and oil on the 'net, and no shortage of dumb statements. I am not an engineer so I don't pretend to be able to a better job of explaining gasoline. Perhaps though I can bring a fresh and reasonable perspective.

The problem with gasoline? Blame cars. Today's pump gas, compared with that of the 1960s and early 70s, is definitely dumbed down. No argument there. Prior to fuel injection becoming standard in the car world, they had what was labeled engine management systems, or EMS. EMS was kind of a dry run for fuel injection. Basically it was computerized carburetors. We saw a little of this on the last carbureted Honda Gold Wing. You want to know how much its carbs were computer comtrolled? Well, even the carbs' air bleeds were opened and closed by computer! Wires everywhere! What EMS did was pave the way for fuel to be dumbed down. With EMS and, later, fuel injection, gasoline doesn't have to have a shelf life, so takimg the aromatics out to improve exhaust emissions is no big deal. Replacing many of these traditional ingredients with oxygenates such as alcohol is now easy too. Cars, and now bikes too, with EMs and fuel injection, automatically compensate for shortcomings in the fuel. Fuel injected vehicles, being computer-controlled, can run almost any fuel now, because they adjust on the fly to compensate. Ignition timing is moved, valve timing is adjusted, even compression ratio on some engines. The government even takes advantage of this modern vehicle adaptability to its fuel and mandates in csrtain shortcomings, so that the pain felt by non-EMS engines is even greater, that is, combustion is strangled somewhat, all in the name of exhaust and evaporative emissions. But they can do this because the revised fuel is invisible to the modern engine. In short, today's gas is made for fuel injected vehicles, and virtually every day even more so. Which means pump gas that works well in carburetors is slowly becoming a thing of the past. History. Obsolete. Irrelevant.

This isn't as bad as it sounds. Where it becomes uncomfortable is for the rider who doesn't understand carburetors and who allows his machine's tune to degrade until the engine is right on that edge of incompatibility. And note, though gasoline is changing nearly every day, largely as a result of more and more federal tinkering, much of what is said about gasoline on user forums is just plain nonsense. Oxygenates, for instance. Though oxygenates bring the potential for problems, these issues are potential only. The poorly-tuned engines, for example. Or, when oxygenates are used in percentages much higher than is presently allowed. Which by definition they aren't. It's not even legal. I mean, the OEMs aren't alarmed by it; why should anyone else be? Each manufacturer lists in its owners manuals the percentages of each of the major oxygenates it deems safe in its products, and they are all well over currently allowed levels. The simple truth is that oxygenated gas has gotten an underserved bad rap. I mean, what the heck, almost all race gas has oxygenates in it, and I know of a drag racer that gets unbeatable results on E85! See my article for more about oxygenated gas.

Then there is engine power and gasoline. More octane does not result in more power. There are only three ways gasoline can add power. First and obvious, if a badly tuned system is starving for fuel and you carefully add fuel as needed. No brainer there. Two, if the fuel is formulated more to be a combustible and less to be a politic, which is what race gas is. Simply un-politicized fuel. The other way gas can add power is if your engine is suffering detonation ("pinging"), because it happens to cut power, and you switch to a gas that reduces detonation. That's it. There is no power in gasoline other than with these three scenarios, that I can think of. Octane is not power, it is the ability to withstand, in remote pockets of the combustion chamber, being pre-heated, without popping off on its own before the flame front has reached it.

I recommend to all my customers that they use fuel stabilzer year-round, whether riding or not. The best fuel stabilizer is race gas. It has nothing to do with octane or lead content, but rather the aromatics (benzene, xylene and toluene), which modern gas has completely removed. Aromatic equipped gas lasts like it did in the 1960s, two to five years. Race gas can be expensive to run year-round, so one workaround is to mix it half and half with pump gas. Next downward in choice is aviation gas. But with av gas you have to be careful you don't get heavily leaded stuff, as it will ruin your cylinder head, and also make sure it is formulated for higher rpm engines, which av gas hasn't been traditionally. So research that before going with av gas. Last on the choice scale is Sta-Bil, which is good enough for both Honda and Kawasaki to stock by part number, but which some folks find difficult to use -- if not used exactly according to directions its effect is reduced. It also doesn't last as long as race gas, but long enough (12 months).


Suggested reading:
Gasoline FAQ, the seminal and definitive treatise by Bruce Hamilton. Actually a four-part tome. A major 1997 classic! Enjoy!
Oxygentated Gasoline
Fuel Economy
Octane

Email me
© 1996-2015 Mike Nixon