The West Coast Sales Manager of Rootes American Motors Inc., Ian Garrad, realized that the Alpine's image was that of a touring car rather than a sports car, and he set about changing its image, using the recent success of the Shelby Cobra as a guide. He and Rootes' Western Service Manager Walter McKenzie measured up several V8 engines and determined that Ford's new 164 hp (122 kW) 260 cu in (4.3 Litre) Windsor V8 engine would fit nicely between the frame rails.
Sunbeam asked Carroll Shelby to produce one functional prototype on a budget of US$10,000. Shelby's prototype was fabricated by Shelby employee George Boskoff, and the result was judged to be good enough to send to England for production evaluation. Seeking reassurance everything would fit, a second Series 2 Alpine was handed to Ken Miles. Ken Miles (a talented racer and fabricator in his own right) had just been employed by Shelby American. Using his own shop facilities, he managed to install a 260 cu.in. V8 and two-speed automatic into the Alpine in less than a week, at a total cost of US$600. Having served its feasibility study purpose, Ken Miles' prototype was kept by Rootes Motors Inc. Los Angeles for some time then eventually sold to a private buyer.
After doing extensive engineering studies Rootes Group subcontracted development and pre-production testing to Jensen, located in West Bromwich, England. Jensen went on to manufacture the Sunbeam Tiger. Production reached 7,085 cars over three distinct series (the factory only ever designated two, the Mark 1 and Mark 2; however, since the official Mark 1 production spanned the changeover in body style from the Series IV Alpine panels to the Series V panels, the later cars are generally designated Mark 1A by current Sunbeam Tiger enthusiasts). Mark 2 production totaled just 536 cars, and these Tigers, with the 200 hp (150 kW) 289 cu in (4.7 Litre) engine, are rare today. Amazingly, both the Miles and the Shelby prototypes survive today, along with a number of other historically significant Tigers. In the first three seasons of Get Smart (1965-1968), Maxwell Smart appears in a red one under the opening credits and theme.
Production of the Tiger only lasted from 1964 until Chrysler purchased Rootes in June 1967. Chrysler could not be realistically expected to sell a car with a Ford engine, but had no suitable engine of its own with which to replace it: Chrysler's small-block V8 engines had the distributor positioned at the rear of the engine, unlike the front-mounted distributor of the Ford V8. Their big-block V8 had a front mounted distributor, but was significantly larger. These made it impossible to fit either Chrysler engine into the Sunbeam engine bay without major, and expensive, revisions. Thus the Tiger was canceled.
Source: Wikipedia Sunbeam Tiger Article.