1991 318iS M50 Build

[wworm]

this thread just got way more involved than I was expecting. Scrolled down to see a turbo manifold and got stoked! What will the final displacement be on a 2.5 with the b30 crank?

[stormtrooper15]

Called a couple shops today for machining estimates and have a couple questions if anyone can answer them. So I planned on just honing and decking the block, and resurfacing the head. I’d have the shop clean everything and do magnaflux on the block. Now mind you I will be swapping in the M54B30 crank, rods, and pistons. Is there other machining people would recommend? Particularly to the head? M50B25 block with M54 internals, 0.140” MLS, and stock head. Also are the M54 pistons forged? Thanks!

[stormtrooper15]

Got the VANOS and head removed today. Excuse the messy garage. Cylinders look pretty good, just lots of deposits on the pistons. Gonna start calling machine shops this week, likely to make the drive over to Houston for machining. Wasn’t able to pick up the M54 today though :/ hopefully this week or next weekend.

[stormtrooper15]

1991 318iS M50 Build



Started the afternoon by replacing the front wheel hubs. Didn’t get to test drive due to rainy weather, should be able to drive tomorrow. Got the remaining accessories removed from the M50. Coolant port and thermostat were caked up pretty good. Also got the valve cover pulled, should have a buddy over tomorrow to help pull the head. And go get the M54b30!

[stormtrooper15]

1991 318iS M50 Build



Got a couple parts in the mail yesterday and today. Turbo manifold, M3 front control bushings, rear shock bushings, short lug studs, and ARP studs for M50 head and main bearings. Replaced the rear shock bushings, piece of cake with an impact.

[stormtrooper15]

Sorry, I have been lacking in updates guys! I have not started engine tear down yet because I am trying to only do one project at a time but may start this weekend. I have been collecting parts for the build and have received ARP studs for head and crank, goodntight T4 turbo manifold, ZF320, M54B30 (for crank, rods, and pistons. Will part out rest of engine if anyone is interested.), and I already had a M50tu with a bunch of miscellaneous parts. Also have an E36 driveshaft that I think will need to be modified to fit the ZF320. I will do my best to get pictures uploaded this evening after work. I am in search of a 2.93 LSD and T4 turbo (ideally 6262) if anyone knows of a decent one for sale! Other than that, the major components should be complete!

[AllydNYC]

What rear diff are you using?

I just did an m52/ZF swap on my 318is.

I used a 2.93 diff. For AZ's fast roads, it's a great. I would go for a low 3.xx LSD diff if highway driving wasn't as fast and we had more canyon roads.

Check out the Excel sheet here to find out the RPM @ speed with each diff and transmission configuration:

https://www.r3vlimited.com/board/showpost.php?p=2783454&postcount=6

[brads2002]

Yeah, just figured the M50 had a similar profile flywheel. It wasn't even close with the s52 flywheel. Assuming he is using the 250 that came with it but where he is swapping into a 318is he probably has a 240 as well.

[Mushroom Stew]

Just FYI the 240 will not fit with the S52 clutch and flywheel. I found out the hard way. The bell housing isn't deep enough. I ended up going with a 260 thats been in the basement for years.

he's doing an m50 swap-same as me.

[brads2002]

Last brake lines I ran I used the copper stuff. Real easy to work with and fairly inexpensive.

[stormtrooper15]

Finally getting the rear brakes, wheel bearings, half shafts, and SS brake lines done. But ended the day stripping a hard line :/ anybody have a passenger side rear hard line for sale?


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[stormtrooper15]

Just did this swap and pretty sure the 318 cable will fit. I had bought the e34 ahead of time so didn't actually try it but they seem very similar.

My e34 cable is all the way maxed to loose. It just fits. I wish I had tried the 318 before removing it and breaking the firewall clip.

I’ll give it a shot when I get to that point and let you know!


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[brads2002]

Just curious- is your 318 a 5 speed? Im doing the same swap as we speak and am keeping the getrag 240. Might save yourself a bit of hassle other than finding a 320i linkage for it.

Just FYI the 240 will not fit with the S52 clutch and flywheel. I found out the hard way. The bell housing isn't deep enough. I ended up going with a 260 thats been in the basement for years.

[brads2002]

Just did this swap and pretty sure the 318 cable will fit. I had bought the e34 ahead of time so didn't actually try it but they seem very similar.

My e34 cable is all the way maxed to loose. It just fits. I wish I had tried the 318 before removing it and breaking the firewall clip.

[stormtrooper15]

My car is currently the M42 with G240 5 speed with 4.10 open. I’ll be swapping to M50 with ZF320 5 speed with ideally a 3.25 LSD. I don’t have the diff yet.


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