The Stag V8 was indeed based on 2 inline fours. I agree that it was insane to waste scare resources to develop, when they already had a lighter and better V8 of similar capacity within the group, especially when you consider the variations of the design.
The 2 F1 world championship winning Repco Brabham V8s were based on the Buick/Olsmobile versions of the RV8, proof enough that the basic design was quite capable of converting to a more modern OHC design, and there were also twin OHC versions.
Incidentally the Repco Brabham engine was designed, developed and made here in Melbourne, Australia by the renowned Phil Irvine, designer of the Vincent Black Shadow and Black Lightening engines as well as the Repco F5000 V8.
The Stag engine was an OHC engine, but quite heavy in comparison, with it’s iron block, in fact the Rover V8 was only @ 18 lb heavier that the inline 4 version of the Triumph engine used in the TR7. There was of course the 16 valve version of the Triupmh inline 4, the Spint, and there were even proposals to use the Sprint heads on the Stag V8, this might’ve improved the performance of the Stag, which wasn’t really a sports car , more of a nice GT with a removable roof.Having said that they gave the Stag a loverly exhaust note.
Triumph themselves ended up, using the Rover V8 in the TR8 anyway!
The rivalry within thePlayland Leyland Group was as mentioned, extreme, Upper management wanted Jaguar to drop the XK inline 6 in favour of the Rover V8, so when Jaguar were designing their XJ40 range to replace the old series 3 XJ6 and XJ12 range the designed the engine bay too narrow to use the Rover V8 engine the result was they had to keep the old XJ12 in production alongside the new XJ40 series XJ6 for some years and then eventually had to redesign the XJ40 platform to widen the engine bay to accommodate the V12 engine.
Playland’s upper management would’ve been better off not indulging in their divide an conquer method of running the group and encouraging a more cooperative approach between the companies within the group and spending money on developing designs properly, instead of leaving the customer to bare the cost of development.
But what else would you expect from a bunch of stupid, politically appointed bean counters who wouldn’t know a car if it bit them on the arse!
"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"