Just found this article on Stanceworks. Pretty cool:
BMW's Secret 7 series model: E32 Prototype with 6.7L V16 engine
"We all can dream, can’t we? When we dream it’s said that we are projecting our inner subconscious thoughts and our deepest desires in a consequence free environment. It’s those dreams that make us wake up tomorrow and explore the ideas that seemed impossible last night before we went to sleep and try and make them a reality. Well, the engineers and minds inside BMW certainly live to dream and it has never been more apparent than in regards to a said, “Secret Sevenâ€. No, this post has nothing to do with Agent 007 and his infatuation with Bimmers, but rather an ambitious secret project involving a 7 Series by Dr. Karlhienz Lange, Adolf Fischer and Hanns-Peter Weisbarth.
All three individuals, Lange, Fischer and Weisbarth, were very senior and influential people at BMW during the mid-70’s and up through the early 90’s. Lange was responsible for powertrain developments, Fischer was involved with all obscure development projects and Weisbarth was most famously involved with the E31 8 Series coupe and E32 7 Series. It was from the mind of Lange that came the M70 5.0-liter V12 engine that was used in the 750i and the 750iL. So it only came natural that the Secret Seven project come from someone so ambitious. Lange instructed Fischer to explore the possibilities beyond the M70 engine. And it was from then that the Secret Seven project was born and BMW’s first V16 engine came into fruition."
"Less than six months after Lange gave the go ahead on the project, Fischer had a complete (and production ready) 6.7 liter V16 engine on a dynamometer on Christmas Eve in 1987. Naturally the numbers on the V16 engine were nothing short of impressive boasting 408 bhp at 5200rpm and 461 ft lb of torque at 3900rpm, more than 100bhp and 100 ft lb torque than the 5.0 liter V12. Within the walls of BMW, the Secret Seven project was also known as the “Goldfishâ€. Reason being, the 7 Series sedan that the V16 engine was fitted into was a golden color so the project was christened the Goldfish.
Now about that golden 7 series…. Naturally the addition of four more cylinders was going to cause some spacial issues when dropping into an unmodified E32 sedan. Obviously it was important for BMW to keep the modifications minimal, just in case there were ever any plans to bring the Goldfish into productions. Although no such promise existed as Lange told Fischer that although he wanted the project to be production ready, he couldn’t promise it would ever see the light of day."
"The V16 engine measured 12 inches longer than the M70 V12 that sat in the bay of the 750i. Extra space in the engine bay was nonexistent with the M70 so the addition of four extra cylinders posed a bit of a challenge. Fischer and his team of engineers did the simplest thing they possibly could and that was to move the cooling system in the E32 into the rear of the car. Naturally this method would never be employed into a production ready vehicle from BMW, let alone any other automotive company, so it was done just for sake of the Secret Seven project and to deem the impossible…. possible. With the cooling equipment in the trunk, engineers hand made custom fiberglass gills and air scoops that sat on the rear quarter panels of the car to channel cool air into the trunk. Air was expelled through a custom made valance panel that sat in between the taillights of the car, which lead to the use of smaller tail lights eliminating the rear high intensity fog and reverse lights.
The engine block of the V16 was made using high silicone aluminum with the pistons running directly inside the bores that had been etched and honed during the manufacturing process so the iron-coated pistons would run against hard silicone crystals. The V12 utilized a seven bearing forged steel crank shaft, so the V16’s crank shafted needed to be modified and utilized a nine bearing crank shaft just as the camshafts did. More modification came in the way of the engine management system. The V12 used two Bosch DME 1.2 units to run two six-cylinder engine and for the added displacement the V16 ran a more powerful Bosch DME 3.3 system that ran the engine as two inline eight-cylinder engines with the own electronically controlled throttle bodies."
"Cylinder dimensions, measured 84×75mm bore and stroke, were kept the same as the original M70 motor and raised the dimensions of the motor from 4988cc to 6651cc. Also both valve lift and timing remained the same between the V12 and V16 engines as well as the 91mm distance between the cylinder bore centers. It literally was unchanged except for the addition of four extra cylinders. Why mess with success?!? Just add onto it! One of the most exciting things about the Secret Seven project probably lies within the gearbox…. it’s a six-speed manual! The gearbox was borrowed from an 8 Series coupe due to cost and timing of the project. Numbers on the saloon were certainly impressive, boasting a 0-60 time of 6.0 seconds flat and a top speed of 175 mph. Fuel economy, as one could imagine, wasn’t the greatest with city driving at 14 mpg and highway at 20 mpg, but this isn’t exactly a hybrid were talking about here.
In the prototype phase, the V16 was ready for full production and BMW did consider building a “Super 7″ of sorts but securing approval from the board was too far fetched and the V16 never saw a garage or driveway. As for the question if BMW will ever use a V16 engine in their lineup of large sedans? The answer is, most likely not. Reason being the economic climate and environmental consciousness of the day simple won’t allow it and would go against BMW’s “Efficient Dynamics†mantra for the present day. Unless they made a V16 hybrid…. but that would just me an oxymoron. The “Goldfish†or “Secret Seven†project is just a demonstration of some of the thinking that goes on behind the doors at BMW. Yes, there are enthusiasts behind those doors, probably thinking up more automobile bliss than one can imagine. It’s reassuring to know that BMW isn’t scared to push their engineers and designers to think beyond the standard and offer their public some of the finest automobiles on the road.
Many of us would have loved nothing more than to see the V16 make it onto the roadways, but hopefully projects like this will continue to inspire engineers and designers to always push the envelope."
-BMW Blog words
