Originally Posted by Maestro
So does anyone know why the switch from Al/Mg to just Al block. I heard there were some issues with the early Al/Mg engines. Al/Mg alloys tend to be a more durable and better cooling performance. So why the change to just AL was it becuase of the those early issues?
Everything you need to know is here:
The N54 engine in the 335i is all aluminium (like the older e46 330i engine) because BMW didn't feel that the newer al/mg engines would be strong enough for turbocharging.
the N52 engine in the e90 330i is still in production - it's the engine that is still used in the 328i.
Confusingly I believe that this is detuned for the US e90 328i, but has also been uprated to a 200kw version in the x3 3.0si etc..
The N52 will ultimatey be replaced by the N53 which will have direct injection like the N54:
As it says in the wiki - this is not really a new engine - more of an upgrade - and it may never be sold in the USA.