Recommendations needed

[Minimrx71]

Hey everyone, I’m new here and in need of some recommendations. Doing an engine rebuild on a 325xi and need to know what oem parts should be swapped out or replaced (looking to get around 420hp out of this 2.5low)….Every mechanic I’ve taken her too has just been butt forking me. So I started doing stuff on my own and man does it feel good as hell to save 3-4K. Don’t get me wrong it can be a headache. Which most of you are aware of. But we all know 4k can go along way for more parts.

[E39 Newbie]

Hey everyone, I’m new here and in need of some recommendations. Doing an engine rebuild on a 325xi and need to know what oem parts should be swapped out or replaced (looking to get around 420hp out of this 2.5low)….Every mechanic I’ve taken her too has just been butt forking me. So I started doing stuff on my own and man does it feel good as hell to save 3-4K. Don’t get me wrong it can be a headache. Which most of you are aware of. But we all know 4k can go along way for more parts.

2.5 liter... naturally aspirated... 420HP? That I'd like to see. Your going to need some form of forced induction, at a minimum. Of course, I have no idea what effect that would have on the stock pistons, so those will need to be upgraded to forged units, I would think. I think the crank would be OK but not sure about the rods. The fuel system (pump, injectors, intake) will be inadequate and the computer won't like any of this. I've seen kits for somewhere within shouting distance of $10K. Have you considered selling it and buying an E90?

[yjsaabman]

The M54 bottom end is pretty stout and can handle some boost. I'd keep it below 8 psi on a stock bottom end, and that will probably get you in that neighborhood. With boost you should run little more ring gap as the higher heat and pressures will cause more expansion which can break the ring lands on the piston. You may get more/better info over at E46Fanatics in the forced induction forum.

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