Quote:
Originally Posted by bquatt
Given that the B48 is a closed deck block, it's not surprising that it'd be able to handle a substantial amount of boost. The N20 was a different story and was more prone to failures from what I've read. Obviously only time will tell but I think as long as people are tuning properly these engines have a lot of untapped potential 
I'm personally waiting for the Dinan Stage 1 flash as I think they're the best in the game. Maybe I'm drinking the kool aid but they just seem to have a reputation for quality, safe OEM + tunes. |
Fwiw the closed deck helps with blown head gaskets but the ultimate limit is likely the rods on a B series (I don't think anyone considers a blown head gasket as "blowing" their engine)
B series all have forged cranks and the B58 has forced and cracked rods as well whereas the B48 and B46 make do with lesser spec rods. With the longer stroke compared with the N series the rods are likely the weakest link on the engine side of things. For a B58 the transmission becomes the weak link with some 600whp tuned cards experiencing tyranny issues and for the B48 it will be the rods for sure given the transmission is the same as the 40i cars but in order to get to that limit with 2 less cylinders your going to be pushing each route 50% harder. (assuming you upgraded your turbo, if you tried this with the stock turbo for sure that won't make it)