Holbay Engineering started out as a small family run British engineering company founded in 1958 by Roger Dunnell, the father of current owner, and his brother John Read specialising in engine modifications and race tuning. Although they enjoyed much success during the 1960s and 1970s with their competition race engines, they are best remembered today for their work on the Rootes 1725cc OHV engines as used in the Hillman Hunter GLS and Sunbeam Rapier H120.

The company was initially run from the family home in Sheffield but moved in 1964 to larger premises at Martlesham Heath in Suffolk, not far from where Dunnell Engines, the current owners, are now situated. 

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Despite the business going into liquidation in 1992 after the untimely death of John Read in an unusual aircraft accident, the intellectual property rights, including the ‘Holbay’ registered trademark, company records together with all engine production details and specifications, passed to the son of the founder, Paul Dunnell, who had served his apprenticeship at the company and worked there as an engineer for some years.

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Paul established his own renowned engine and race tuning business, Dunnell Engines in 1989 and absorbed the renamed Holbay Racing Engines Ltd into the Dunnell business and remains the source of knowledge and expertise for Holbay engines today.