Ford Motor Co. is boosting its projection for sales of Ford F-150 large pickups equipped with six-cylinder EcoBoost engines, responding to greater than expected demand, Ford truck group marketing manager Doug Scott said Thursday.

Ford had expected that about 40 percent of F-150 pickups sold to individual customers would be equipped with the 3.5 liter EcoBoost engine. “We didn’t think we would be exceeding that target,” Mr. Scott said.

Now, the company expects EcoBoost equipped models will account for about 45 percent of retail F-150 sales going forward, he said. Retail sales of EcoBoost F-150s should total about 100,000 vehicles in 2011, he said. Through the end of September, retail customers had purchased about 75,000 F-150s with the six cylinder engine, reported The Wall Street Journal.

Total Ford large pickup sales, including heavy duty pickups and vehicles sold to fleets, are up nearly 8 percent to 416,388 vehicles for the year through Sept. 30. Rival Detroit brands Chevrolet, GMC and Dodge have racked up larger percentage increases in sales, but the F-series remains the segment leader by a wide margin. Japanese auto makers Toyota Motor Corp. and Nissan Motor Corp. have suffered sales declines of 11 percent and 12 percent respectively for the year to date.

The large pickup truck market has been dominated by V-8 engines for decades. As recently as two years ago, Ford didn’t offer a six cylinder motor in its F-series lineup.

Pressure from federal regulators to boost fuel efficiency and customer anxiety about volatile gasoline prices have combined to push auto makers to reconsider traditional marketing formulas, including the idea that there’s “no replacement for displacement” in the big pickup market.

Ford launched the EcoBoost engine in the F-150 line in February. During the last few months, sales of EcoBoost models have accounted for about 42 percent of total F-150 sales, Mr. Scott says. EcoBoost equipped F-150s average 18 miles per gallon in combined city and highway driving, according to federal government ratings, compared to 14 to 17 miles per gallon for eight cylinder models.

Ford’s production of EcoBoost-equipped F-150s should catch up with demand by late 2011 or the first quarter of 2012, Mr. Scott said.