DETROIT General Motors is laying off 560 workers while it retools an engine plant near Detroit to build a new motor.

GM says layoffs at the Romulus, Mich., factory will start in August and run to late 2015. The company is rebuilding the inside of the factory to make a new, more efficient V-6 engine.

The plant now builds several V-6 and V-8 motors for trucks as well as industrial and marine uses.

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When the $390 million upgrade is finished, the plant will make only V-6s.

During the layoffs, about 430 full-time workers will get unemployment and supplemental pay worth about 75 per cent of their wages. Another 130 temporary workers will lose their jobs.

GM announced the retooling in 2011. about 120 skilled employees will stay while the work is done.