Are tired, old fuel injectors robbing performance?

A little science fact you might have missed in school: Liquids cannot burn. Only vapors can. 

“Flammable and combustible liquids themselves do not burn,” confirms the National Association of Safety Professionals. “It is the mixture of their vapours and air that burns.”

Gasoline exists as a liquid for transportation and storage. To actually combust and make the horsepower we all love, it needs to transition into a vapor state.

Enter the fuel injector. Its job is simple: Mix that liquid fuel with air so the required combustion can occur. 

The smaller the droplet, notes Zachary J. Santner, senior specialist of quality at Sunoco, the better it mixes with the air for combustion. The scientific reason, he continues, is because the barrier has been increased between the liquid and vapor phases by creating more surface area. “The surface area is a function of radius,” he says of the drops. 

For a Mr. Wizard DIY science experiment, Santner says to pour a few ounces of water into a low, wide bowl. Then fill a tall, thin glass with the same quantity of water. Now place the two containers side by side. The water in the bowl will evaporate quicker because it has more surface area. 

The same holds true for gasoline. All else being equal, millions of tiny droplets of gasoline will burn quicker than one big drop. 

So, how to chop up your gasoline into those millions of tiny droplets? Look at your fuel injectors: How healthy are they? 

For daily maintenance, Santner recommends a Top Tier fuel as they’re packed with extra detergents–and, he notes, all grades of Sunoco street fuel are on that list. Fuel filters should also be changed at regular intervals. 

Fuel injectors can also be sent out for professional cleaning. Figure less than $30 per injector for a complete cleaning and inspection. An injector that dribbles, even a little, is hurting performance as it’s preventing proper combustion.

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