Originally Posted by M3_WC
They can no longer make a limited model like the E46 GTR V8, as the rules do not allow it.
The rules will specify some mimimum number of production cars that must be built using a version of the engine in the race car. BMW will simply meet that minimum, probably in a car not unlike todays GTS.
Another possibility is that they will just run the turbo 6 from the standard car in the race car. Engines are trending toward FI in some race series such as Indycar and even F1 is being urged to switch to turbo I4. I'm not sure of the rules for ALMS or Le Mans but I could easily see them allowing FI in the GT class soon if they don't already.
Originally Posted by erhanh
Slightly off topic, but I always wondered this about fuel economy. Since the main driving reason for BMW is to be green, I thought I'd ask this question here. Forgive my lack of knowledge.
A V8 engine is two I4 engines bolted together in V shape. Could it be possible to use only one of the I4 banks for let say cruising? If possible, I think that'll be 'green'. We'd have the full V8 for normal usage. And manually or automatically (which can even be programmed in to M drive), we can switch to single I4 mode for high way cruising...
Yes, GM and Chrysler already employ this technique on some of the V8s. It is easier to engineer on a pushrod motor because of the level of indirection between the cam and the valves, and the available space to work with since the cam is in the black. But it could be done with OHC engines as well (I am sure prototypes exist). The thing is the gain in efficiency isn't as high as you might expect, mainly because you end up with so much rotating mass that isn't contributing to the power output. A better idea might be to literally place two I4's in tandem (joined by a differential) and just shut one down completely. But the costs would skyrocket on that, and plus the packaging would probably be nightmare.