[Kkohnnnnn]

I’ve got a 2016 m235i FBO, BB3.4 kit, spool fx-180 HPFP, dual walboro LPFP, Port Inejction on full e85 tune. Starting to build the engine. I’ve got the rods picked out but as for pistons, the engine is stock bore stock compression, does anyone know if the 84mm bore and 9:2:1 compression pistons will fit? Here’s the link to them just want to make sure they fit before I order.

https://store.vacmotorsports.com/mob...n55-p2960.aspx

Thanks!

[jb-slow]

You need to measure each bore individually to see what they are and if they're in spec before worrying about pistons. You usually need to machine a little bit to correct a out of round condition. In that case you'd order pistons that are bigger than the out of round condition and bore the block to the pistons size.

[aerobod]

Originally Posted by jb-slow

You need to measure each bore individually to see what they are and if they're in spec before worrying about pistons. You usually need to machine a little bit to correct a out of round condition. I that case you'd order pistons that are bigger than the out of round condition and bore the block to the pistons size.

Re-bore is not a viable option with the B58 block as the electric arc deposit coating on the cylinder walls is only about 0.3mm thick. VAC does provide an aftermarket sleeving service, though: https://store.vacmotorsports.com/vac...b58-p5298.aspx

Update - sorry I see this is an N55 re-bore issue, not sure that the same electric arc sputter coating is used, so traditional re-bore may be viable.