[yayaya]

I've been told my n55 engine may be on the way out, mechanic suspects I may have some camshaft scoring. If this turns out to be the case I'm looking at a rebuild. Will an S65 work with the xi and auto trans in my 335xi?

[Azines]

I'm not sure about fitment/compatibility etc. , but I don't know if you looked how much an S65 motor goes for, it will set you back quite an amount...

How much would a rebuild cost?

[Pladi]

anything can be done but is it worth it thats the question... replacing cams/head is a much easier option.

[yayaya]

Originally Posted by Azines

I'm not sure about fitment/compatibility etc. , but I don't know if you looked how much an S65 motor goes for, it will set you back quite an amount...

How much would a rebuild cost?

I took a quick glance on eBay and found a few for 9k.

[Azines]

Yes a motor with 100k+ miles will cost that much, but given the risk of those motors with that mileage, I'm not entirely connived if its wise spending that much on an S65 versus a new rebuilt N55 which will run you half that price.

But yet again it's all up to you, if you do decide to go that route, I'd keep in mind too look for newer rebuilt S65's.
It will cost you about 2k more but you'll have a piece of mind that the motor was done from top to bottom and looked over, and if you're up for a project of this scale, I'm sure that amount will be nothing and pay off in the long run.

[BioChemBro]

A guy on M3post is selling his s65 and trans for ~$6k right now iirc

[SnapCoupe]

You're going to be in to this for FAR more than 9k. You will have to either swap a DCT or a manual to pair with the S65, as the auto would require custom fab work to fit along with custom software to make it work. On top of this you will also need the ECU, running gear, gauge cluster, etc, etc to make the swap possible. To do this right I would say it's no less than 20-25k, which is right about what a 2008 E9X m3 goes for.

I spun my rod bearings on my N55 at 84k miles. I decided to buy a new crate N55 and swap it in as I was able to use my employee discount to get the cost down to around 13k (typically 22k). If the car is worth keeping to you, rebuild the motor with upgraded parts and you will be able to walk on M3s all day long.

[yayaya]

Originally Posted by SnapCoupe

You're going to be in to this for FAR more than 9k. You will have to either swap a DCT or a manual to pair with the S65, as the auto would require custom fab work to fit along with custom software to make it work. On top of this you will also need the ECU, running gear, gauge cluster, etc, etc to make the swap possible. To do this right I would say it's no less than 20-25k, which is right about what a 2008 E9X m3 goes for.

I spun my rod bearings on my N55 at 84k miles. I decided to buy a new crate N55 and swap it in as I was able to use my employee discount to get the cost down to around 13k (typically 22k). If the car is worth keeping to you, rebuild the motor with upgraded parts and you will be able to walk on M3s all day long.

Yeah it's not worth to me 22k to me to put into a car with 99k on the clock, not sure why I thought it would be cheaper to do. I guess my 335xi will be my limp mode mobile while I save for an f80 m3.

[renizer]

Originally Posted by yayaya

I've been told my n55 engine may be on the way out, mechanic suspects I may have some camshaft scoring. If this turns out to be the case I'm looking at a rebuild. Will an S65 work with the xi and auto trans in my 335xi?

in short: no.
longer answer: not without a substantial amount of custom work. the V8 has at least some other bellhousing, maybe input shaft, etc. if you're lucky you could buy M3+trans and swap the ATC to that trans. maybe. and i don't think the S65 comes with block/oilpan etc needed to mount your FAD to. and this is just talking about the obvious mechanical stuff.