The Benefits of Direct Injection for Fuel Efficiency

Fuel Efficiency

In the next few years, the average fuel economy will increase as required by the federal government.

An engine with direct injection gets about 10 percent more power, uses about 10 percent less fuel and emits fewer pollutants. The CAFE (corporate average fuel economy) will double in the next 15 years. Many innovative fuel-saving, power-boosting technologies will be used on the next generation of power trains. One of the most intriguing is direct injection. This type of system injects fuel directly into an engine’s combustion chamber under very high pressure. Injection pressures vary between 22,000 and 30,000 pounds per square inch. As a comparison, the water pressure in an average home’s plumbing system is about 80 PSI.

The advantage of this system is much more control of the combustion process. An engine with direct injection gets about 10 percent more power, uses about 10 percent less fuel and emits fewer pollutants. So why don’t all engines include direct injection? The simple answer, for now, is that the system costs more and is somewhat unproven in the long term.

One of my readers wanted to know about the dependability of a system that involves such high pressures. When a new system comes out, it takes a number of years before the dependability is known. And in fact, one of the earlier adopters of direct injection has had problems with the high-pressure pump, a mechanical device that runs off the camshaft. The cam and all the components that develop the high pressure have been wearing out prematurely. The good news is, the manufacturer is putting a longer warranty on this system, up to 100,000 miles even without proof of oil services. My suspicion is that infrequent oil changes have something to do with the early failures of this pump. As with many advancements in technology, we take five steps forward and fall one step back.

Direct injection is here to stay, and as it is more widely used, the price will come down and dependability will improve.

-George Rode (check our our commercial below)

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