The ‘I4′ DOHC engine first introduced in the Ford Sierra and Granada models of late 1989 was only available in the Sierra in 2.0-litre 8-valve form. While power output improvements can be made to the stock 2.0 8v engine, as documented in a separate article entitled ‘DOHC tuning’ and available from http://www.crustworld.co.uk/sierra/dohctuning.pdf, the engine output is ultimately limited by the availability and cost-effectiveness of off-the-shelf tuning parts.
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