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I suspect that the water-to-air aftercoolers are a packaging requirement, not for performance, given the rather long intake ducting. Intake plumbing goes from the cold intake, to the top of the engine, to the back of the engine, and back along the top to the turbos. After the turbos, there are the water-to-air aftercoolers before the intake manifold. Look at the composite manifold; it would be very easy to optimize the flow in that manifold given the manufacturing process. Probably pretty light weight too. It doesn't appear that there will be an air to air aftercooler as with the inline 6 twin turbo engine. That will help with packaging as well.
Why the long intake ducting? Looks like a trade off to get an incredibly short exhaust run from the manifolds to the turbos. That will mean very little turbo lag, partly due to the twin turbos and partly due to the short run. The heat worries me, especially when you see what looks like a catalytic converter right after the turbos. Having the converter very close to the engine will mean quicker warm-up, and better emissions test results, but that is a lot of heat to manage under a tight hood, with two manifolds, two turbos, and two converters, none of them in the airflow.
As Josh notes, the pistons look special. See how short the skirts are, they look light.
I am impressed by the detail in the engine, such as the beautiful exhaust manifolds that no-one will ever see. Even better though is that BMW went to the trouble to build these mock-ups, demonstrating what they are doing as an engine company.
I am wondering about the tuning potential. With a stated 400 hp, this engine has a lower specific output than the 3.0 twin turbo; it could have 440 lb to start, especially considering how the 3.0 appears to have been under-rated by the factory. Vishnu and others would take this to 500 hp quite easily, and if the responses are anything like the 3.0 then the 4.8 naturally aspirated engine is dead and gone as a performance engine.
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2007 X3 3.0si, 6 MT, Premium, White
Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue
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