I thought the 6r4 engine was a rover v8 minus two cylinders?

Gavin.

Thought so.....

In terms of an engine, there was little consideration given to using an existing ARG engine (supercharged or turbocharged), but due to what they were likely to be up against, the brave decision was taken to produce a bespoke engine for the new car. Two engines were apparently tried in development prototypes during late 1983: the Honda V6, due to appear in the Rover 800 in 1986 – and the Rover V8. Needless to say, Patrick Head preferred something lighter and more compact – and pushed for an all-new V6 loosely based on the Rover V8. From the initial design of a V6 version of the Rover V8, it was development engineer Cliff Humphreys at Cowley that managed to move the concept towards reality; making it work beatifully – thanks to a lot of hard work. From there, Stan Johnson and Rob Oldaker at Longbridge completed the transformation.