Porsche has been building water-cooled 911s for 25 years.

The water-cooled Porsche 911 was once unimaginable, but Porsche has been building water-cooled 911s for 25 years.

Porsche began introducing water-cooled road cars in the 1980s in the form of the 924, 944, and 928. However, Porsche's flagship 911 remained water-cooled, which was considered an important part of its identity. It was difficult to break with tradition, as Porsche had been building air-cooled, rear-engine sports cars from the beginning.

The end of the air-cooled Porsche finally came when the 996 911 was presented at the 1997 Frankfurt Motor Show. The flat-six engine was in its usual place, but this time it was air-cooled.

"We experimented with the engine because the air-cooled two-valve, one-cylinder design had reached its technical limits in terms of emissions and power," August Achleitner, then head of Porsche's technical product planning, vehicle concept and packaging, said in a statement.

"And the various air-cooled four-valve boxers did not work due to various hot spots that we could not handle."

Porsche experimented with the 911's V-8 engine in 1989, and the switch took a long time, according to Achleitner. It was the most thorough redesign of the 911 to date, including the elimination of the classic round headlights, unusual styling (which returned in the 997 911), and sharing parts with the original Porsche Boxster. In other words, it was the perfect time to switch to water-cooling.

Predictably, some Porsche fans were appalled and insisted that they would never touch a water-cooled 911. However, the car was a success, selling 175,000 units during its marketing period. The parts sharing concept allowed Porsche to develop and produce the Boxster on a relatively limited budget. Unencumbered by tradition, Porsche introduced the Cayenne, securing its financial future, which would not have happened without the 996 911, so the 996 911 was, with all due respect, truly a watershed moment for Porsche.