I have a DOHC 4.6 aluminum mod motor in my '04 Mercury Marauder and it has 211K+ miles on it with the last 128K miles Supercharged!!
It has never used a drop of
oil between 5K mile changes and runs like new making over 400 RWHP......I haven't dynoed it but most with ProChargers are making 425-450 RWHP!!
I would expect modern FE aluminum blocks will last a long time with reasonable maintenance.....I'm sure most of you "OVER DO" your maintenance.....so I think life expectancy of aluminum blocks in street cars should be as good or better than iron blocks!!
My $.02 FWIW!!
