People shouldn't try to read too much into posts after all it is an opinion. The information that was relayed to me about the 1500cc 16V Giulia coupe was given to me from the previous Late owner( whose name I wont disclose due to Privacy considerations). I have no reason to doubt him as he was an avid collector of Alfa's as well as a learned Gentleman. I suspect that he had a very good relationship with Autodelta as he not only had that prototype but also an Ex-Autodelta GTAm, 1600GTA Corsa. a Monza as well as a 2 litre 16V Alfetta GT Gr.2 Rally car that has been documented in my Turbodelta book! I have also read on another forum that Autodelta didn't sell its experimental/special prototype to normal customers, some were placed in storage ( Museum) others were sold off or destroyed.You are lucky just to own one of these cars let alone a number of rare ex-Autodelta racing machines. Most of these cars were hidden away from public eyes but I knew of his collection when he invited me to see them back in the early 90's. Most of the mechanics from Autodelta's early inception days are no longer with us and because of that a lot of knowledge and references about their development and experimental engines/cars has been lost. On top of that only those Autodelta staff involved with the development and experimental side would know about these special projects. For example Vin Sharp who recently restored the Brian Foley GTAm tried to find out the history/origin about his car. Even the Alfa Historic archives do not have this information but I did manage to find out the name of the actual person at Autodelta who was in charge of this transaction but due to the passage of time even he couldn't remember much about its history! After the Fiat takeover much of the records were destroyed or lost. Also after the Fiat takeover many of the ex-Autodelta personnel were horrified that many original moulds and castings were destroyed or trashed. As for the origins of the 1500cc 16V engine, to throw some light on the matter, One of the very first mechanics from Autodelta's inception days told me that each year Autodelta manage to develop a different/new specification engine. This may be the reason why this is a 1500cc engine because Autodelta experimented with many different bore /stroke ratios. You only need to look at some of the 1600 GTA bore/stroke ratios and the 1300CC bore /stroke ratios. Even though as Olaf states that the capacity 1600cc didn't change, this wasn't a reason why Autodelta didn't utilise a smaller capacity but higher reving engine to produce a higher power output with a smaller capacity engine. One should also remember that when Autodelta was developing the GTAm engine for Gr.2 (105 1750) they didn't have a 2 litre block hence the Siamese linered 1779 block. You only need to look at the later Alfacorse 75 Evo motors. even though they are 1.8( nom) to stay under the 2.5 liter turbo'ed capacity, the Evo motor still had a special bore /stroke ratio ( 79.6x88.5 ) 1761 cc which was different from the Stradale 75 Turbo (80x88.5) 1779cc. Even the later DTM 2.5 V6 60deg. engines though small capacity revved to 1200rpm to achieve max 400+ HP. The later DTM engine developing near 500Hp was loosely based on a production Montreal block of 90 Deg. configuration but that is another story in itself.Much of my information has been transmitted to me by Ex Autodelta staff of that era who were involved with the development and or purchasing. Even in Tony Adriens original Allegerita book where he showed photos of the rare 3 existing GTA-SA engines , I already had seen them years before that publication. I have been privileged to also learn a lot about the internal politics within Autodelta as well as their relationships with rival competitors Lancia, Fiat, Ferarri but much of it is too controversial to disclose and even if it were most of you would be sceptical that it ever happened! I have also been lucky to learn about the factory Alfacorse DTM No.1 team and about Alfacorse2 team and some of the things that went on there. Maybe someday I will write a book about that episode.