m20b25 swap into 1991 318is...

[bhammett5370]

Hello Everyone,
I recently realized that my headgasket in my 318is is on the way out.So i started to think of different engine swaps.The m20b25 seems the most practical and cheapest solution.I have researched some and found the wiring harness from the m20b25 will plug into the body harness i currently have.Which makes a nice easy swap(if thats correct information).My tranny and rear end are mint.I would like to keep these if thats possible?Anyone know of the other necessary parts?ECU?Mounts?Etc?

[trry96]

Hello Everyone,
I recently realized that my headgasket in my 318is is on the way out.So i started to think of different engine swaps.The m20b25 seems the most practical and cheapest solution.I have researched some and found the wiring harness from the m20b25 will plug into the body harness i currently have.Which makes a nice easy swap(if thats correct information).My tranny and rear end are mint.I would like to keep these if thats possible?Anyone know of the other necessary parts?ECU?Mounts?Etc?

I can't speak for the wiring harness, but I know the tranny is not interchangeable. I just put a "new" m20b25 in my 325is. In hindsight, I would have rather saved up a bit and swapped in an M50. All of the work that goes into a project like that is better spent going towards an engine you can really be proud of. The m50 is a better engine in every respect. You have to pay to get a few things custom made, but it's not that bad...and you'll be very proud of your unique ride.

^ = my $.02

[bhammett5370]

I can't speak for the wiring harness, but I know the tranny is not interchangeable. I just put a "new" m20b25 in my 325is. In hindsight, I would have rather saved up a bit and swapped in an M50. All of the work that goes into a project like that is better spent going towards an engine you can really be proud of. The m50 is a better engine in every respect. You have to pay to get a few things custom made, but it's not that bad...and you'll be very proud of your unique ride.

^ = my $.02

Thanks for the info.Although i really just dont care about going all out crazy with it.I would rebuild the m42 if it was the cheapest route.I can not find any rebuild kits for it however.I can pick up a m20b25 cheap.I have read several places that the getrag 240 tranny will bolt right up?Anyone else have info?

[mattdk318i]

im pretty sure the M20 will bolt up to the 240. But im not sure about the wiring either

[e30_kid89]

Sorry but the 240 won't bolt-up properly to the m20 block. The angle will be 10 degrees off to the left. Save and do a m50 NV swap.

[FredK]

If you do a M20 swap, you need to use the whole drivetrain, from tip to tail. This includes the Getrag 260, driveshaft, and medium case diff.

You should be able to source an M42 from a salvage yard 91 318, or you can use the block and head from a E36 318i/s with an M42, and get E30 upper and lower oil pans.