[mjg0915]

Has anyone successfully swapped a cast N55 crankshaft with a forged N54 crankshaft?

What modifications are required to put the N54 crank in an N55?

I'm having difficulties finding enough detailed specifications to figure out exactly what goes into making this happen.

Maybe this thread can serve as a checklist for anyone else planning to do this as well.

Thanks in advance!

[ferocity02]

Why?

[TunafishE93]

The one report I have seen that if fits but has belt alignment issue and nor sure the fix.
Starting at post #25 https://bmw.***********.com/threads/...ge-2?view=date
The n55 crank will handle anything you're going to throw at it, so the swap will be just to say you have done it.

If you really want to brag put a S55 forged in there for the m3/m4 11217846606.

[mjg0915]

Originally Posted by ferocity02

Why?

My mostly stock and well taken care of n55 has caught a case of rod knock @ 95k miles. I have a good n54 crank on hand.

[mjg0915]

Originally Posted by TunafishE93

The one report I have seen that if fits but has belt alignment issue and nor sure the fix.
Starting at post #25 https://bmw.***********.com/threads/...ge-2?view=date
The n55 crank will handle anything you're going to throw at it, so the swap will be just to say you have done it.

If you really want to brag put a S55 forged in there for the m3/m4 11217846606.

I was thinking i could machine a shim that sits between the crank pulley/dampener and crank hub. Copper washers might do the trick, but i'd prefer a single piece as opposed to 6 little ones to avoid any extra vibration.
I'm not in this to build out a ton of power so i realize it's overkill for my purposes.
At least the foundation will be there.

[TunafishE93]

Well let us know.. I didn't find too much except the one post.. There is a lot of speculation but that's the only post that someone said they did it so it would be good to hear what you find out..

[feuer]

Originally Posted by mjg0915

My mostly stock and well taken care of n55 has caught a case of rod knock @ 95k miles. I have a good n54 crank on hand.

What else you have from n54?

[mjg0915]

Nothing else as far as internals go. I think i have an OCZ, some hoses, and a window regulator somewhere. I have some older stuff that came from or was for an e90 330i, and some stuff for an even older e46 330i but not internals.

I wish i still had that e90 330i....best all around car I'll probably have owned in my lifetime.

[mjg0915]

Originally Posted by TunafishE93

Well let us know.. I didn't find too much except the one post.. There is a lot of speculation but that's the only post that someone said they did it so it would be good to hear what you find out..

I will post back as it goes along. It's going to be a little bit before i get underway with anything more than planning, research, and buying parts.
So far the only thing I've found as an obstacle (if you can call it that) is the n54 crank hub and dampener causing the belt alignment to be off, but i think it's less than 2mm and could be solved with a shim.

[bbnks2]

Originally Posted by mjg0915

I will post back as it goes along. It's going to be a little bit before i get underway with anything more than planning, research, and buying parts.
So far the only thing I've found as an obstacle (if you can call it that) is the n54 crank hub and dampener causing the belt alignment to be off, but i think it's less than 2mm and could be solved with a shim.

I can't see how an N54 crank with an N54 damper and N54 belt tensioner should be of any issue. I definitely wouldn't shim a crankshaft that's just crazy. Pretty sure I replied to your posts elsewhere but what damper and tensioner are you using? Using an N54 tensioner on an n55 causes the belt to slip off so There IS something different there.

[weehe126]

I have a N55 crank for sale if you want to go that route.