The new names for Porsche's two-door, mid-engined sports cars reference the series of 718 racing cars built between 1957 and 1962.
Porsche will introduce the 718 Boxster and 718 Cayman "over the course of 2016".
And the roadster will be positioned at a higher price level than the coupé, as is the case for the larger 911.
"The 718 model series is a continuation of the proven four-cylinder concept and the history of distinguished Porsche sports cars," said a statement from Porsche.
Porsche already uses a turbocharged 2.0-litre V4 engine in its successful 919 Hybrid Le Mans racer.
In the 718 Boxster, a 2.0-litre engine is tipped to be offered in two different power outputs: 261bhp in the base car and 311bhp in the S model, with torque outputs for the pair rated at 258lb ft and 295lb ft respectively. Expect the regular 718 Boxster to have a 0-62mph time of around five and a half seconds, and the S to dip below five seconds
Porsche has traditionally given the Cayman more power, but with the positioning of the 718 Boxster above it, it is not clear if this trend will continue.
Six-cylinder engines are set to be the preserve of more powerful range-topping versions of the two sports cars, including GTS versions and any future 718 Cayman GT4 or 718 Boxster Spyder.
The four-cylinder engines will also reduce the kerb weight of the two sports cars, in turn improving the economy (which is the main reason for the adoption of the new engines) and the handling.
Interestingly, the confirmation of the flat four engine for the 718 Boxster and Cayman stated that "the 919 Hybrid has opened up the prospects for the performance potential of future sports car engines from Porsche", hinting that hybridisation could be part of the future plan for the new road car engine, too.
A hybrid 911 is planned as part of the next-generation line-up, but when discussing the four-cylinder engine in the past Porsche has always distanced the engine from the 911.
Ex-Porsche chairman Matthias Müller, who now leads the entire Volkswagen Group, has also previously said the new four-cylinder engine is modular, and that it will be offered in capacities up to 2.5 litres, with a power output of 395bhp expected in the most powerful versions.
The facelifts for the two sports cars will bring with them styling and interior changes, as well as chassis and suspension tweaks.