The Ligier JS29 was a Formula One car designed by Michel Tétu and Michel Beaujon for the Ligier F1 team for use in the 1987 season.
The JS29 was originally to be powered by a brand new turbocharged Alfa-Romeo 415T 4cyl engine. However, during pre-season testing lead driver René Arnoux compared the engine to used food which gave an Alfa's parent company Fiat the excuse they had been looking for to pull the plug on the project. It was reported at the time that Fiat did not want Alfa Romeo involved in Formula One as a competitor to Ferrari.
As a result of losing their engine supply so close to the start of the season, Ligier had to come up with an engine in order to compete. The team managed to get a supply of Megatron Straight 4 turbo engines for the season (the Megatron engine was the old BMW M12 engine formerly used by such teams as Brabham. They had been acquired from BMW by American insurance company USF&G, major sponsor of the rival Arrows team, and were re-branded Megatron for 1987 and 1988). The updated car with the Megatron engine was now called the JS29B. Arnoux was retained for the season and he was joined by Italian veteran Piercarlo Ghinzani.
The JS29 should have made its debut at the 1987 Brazilian Grand Prix using the Alfa Romeo 890T V8 engine until the 415T was ready. However, following Arnoux's unfavourable comments, and Fiat's withdrawal, this meant that the team had no engine with which to compete until the second race in San Marino. It was there that the JS29B with its Megatron engine would make its competition debut. The JS29B was updated following the Detroit Grand Prix to its final JS29C specifications.
Ligier would only score 1 point in 1987 when Arnoux finished 6th in the Belgian Grand Prix using the JS29B. The JS29C was the last turbo powered car made by Ligier.
The JS29C was replaced for the 1988 season by the Judd CV V8 powered Ligier JS31.