The 8140 was a diesel engine made by Sofim for cars. Originally introduced as a swirl chamber, naturally aspirated diesel it was mostly used in commercial vehicles worldwide.

At the time of introduction, the 8140's overhead camshaft layout (driven by a toothed timingbelt) was unexpected in a diesel engine, which were typically overhead valve designs. Turbocharging the original engine, the design of which was finished in 1974, was impeded until 1985 due to restrictions of the original design. Heat flux issues with the aluminium head and swirl chambers were eventually overcome, but did slow down development. Before entering the market, Fiat tested the Sofim engine in its 131 model during the 1977 London-Sydney Marathon.

First direct injection models also appeared in the mid-1980s.

Additionally to the Fiat designation 8140 some engines got a Renault tag (S8 for indirect injection, S9 for direct injection).

In the early beginning there was a 2-litre (1,995 cc) four-cylinder 65 PS (48 kW), called the Sofim 8144.65. Alongside the 2.4-litre version it was used in light commercial vehicles like the Saviem SG2, the first-generation Fiat/Iveco Daily (also marketed as the OM Grinta, Alfa Romeo AR8 Unic Daily, and Magirus Daily), as well as passenger cars like the Fiat 131 and 132 models. It also saw use in the Fiat Campagnola.

The original 2.4 L big block displaces 2,445 cc (149.2 cu in), with a bore and stroke of 93 mm × 90 mm (3.7 in × 3.5 in).

In 1990 the 2.5 L was introduced with a longer stroke, increased by 2 mm to 92 mm. The bore remained unchanged at 93 mm, this version displaces 2,499 cc (152.5 cu in).

The 2.8 L displaces 2800 cc having a larger bore and stroke of 94.4 mm × 100 mm (3.72 in × 3.94 in).