The Bristol Titan was a British five-cylinder air-cooled radial engine, designed and built by the Bristol Aeroplane Company in the late 1920s. It had the same size cylinders as the earlier Bristol Mercury engine, 5.75 in x 6.5 in (844 cu in/13.8 L) and produced between 200-240 hp. Later versions of the Bristol Titan also used a Farman style reduction gear produced by Gnome-Rhône.
The engine was designed as a five-cylinder radial to use as many parts of the Bristol Jupiter as possible, cylinders, pistons, articulated connecting rods, crankshaft and other minor parts were interchangeable with the Jupiter.
The major significance of the Titan was that it was licensed to Gnome-Rhône and became the pattern for the Gnome-Rhône 5B and 5K. In 1927 Gnome-Rhône was looking for ways out of its license agreement with Bristol for the Jupiter engine of 1920 and began to produce the Gnome-Rhône 5B and 5K without royalties.
Gnome-Rhône was not satisfied with simply producing Bristol designs under license, and started a major design effort based around the mechanicals of the Titan engine. The results were introduced in 1927 as the K-series, spanning the 260 hp (190 kW) Gnome-Rhône 5K Titan, the 7-cylinder 370 hp (270 kW) the Gnome-Rhône 7K Titan Major, and the 9-cylinder 550 hp (405 kW) Gnome-Rhône 9K Mistral. With the introduction of the K-series, Gnome-Rhône finally ended royalty payments to Bristol, the Gnome-Rhône 5K was built in much greater numbers than the original Bristol Titan. By 1930 they had delivered 6,000 Jupiters, Mistrals and Titans, making them the largest engine company in France.