Engine Swap Advice

[Greekchief]

Hello!! So After Restoring My 1987 325es and using it as my daily for the last few months. I finally got around to getting a parts donor from Tennessee. A 1990 325i. My intentions were to take the motor and swap them out. Yet im not sure what the best combination i can use when it comes to the engine.

Is there a good guide to help me understand what my options are? I know i don't have a super eta as its production date is in 1989. I just want to make sure. Is it better to just swap the whole i motor? Or should I only use the head from the i motor and keep the bottom while replacing everything else that the i motor needs to run properly?

I know the donor looks awful, it was crushed by other vehicles while parked for years. My hope is to restore it someday but i cant say for sure if that will happen.


IMG_20250522_071014834_HDR.jpgIMG_20250522_070922877.jpgIMG_20250522_071046784_HDR.jpgIMG_20250525_151844194_HDR.jpg

[82eye]

Hello!! So After Restoring My 1987 325es and using it as my daily for the last few months. I finally got around to getting a parts donor from Tennessee. A 1990 325i. My intentions were to take the motor and swap them out. Yet im not sure what the best combination i can use when it comes to the engine.

Is there a good guide to help me understand what my options are? I know i don't have a super eta as its production date is in 1989. I just want to make sure. Is it better to just swap the whole i motor? Or should I only use the head from the i motor and keep the bottom while replacing everything else that the i motor needs to run properly?

either do a stroker or a straight i swap. it all depends on your goals. if you want a stroker to chase power read up everything you can on the stoker build. there are bibles and bibles and bibles of compiled info on the swap. it's not hard to find.

you don't need the super e to build a stroker but it is a shorter and easier process. most folk start with a regular e and go from there.

there is an entire sub-forum at R3V dedicated to documenting the swap. try reading up on it there. no one will spoon feed you. you can probably glean enough info off this forum but it is not in one place or complied very well.

I know the donor looks awful, it was crushed by other vehicles while parked for years. My hope is to restore it someday but i cant say for sure if that will happen.


IMG_20250522_071014834_HDR.jpgIMG_20250522_070922877.jpgIMG_20250522_071046784_HDR.jpgIMG_20250525_151844194_HDR.jpg

ouch. that one looks too far gone to be anything but a parts car.

[Greekchief]

either do a stroker or a straight i swap. it all depends on your goals. if you want a stroker to chase power read up everything you can on the stoker build. there are bibles and bibles and bibles of compiled info on the swap. it's not hard to find.

you don't need the super e to build a stroker but it is a shorter and easier process. most folk start with a regular e and go from there.

there is an entire sub-forum at R3V dedicated to documenting the swap. try reading up on it there. no one will spoon feed you. you can probably glean enough info off this forum but it is not in one place or complied very well.










ouch. that one looks too far gone to be anything but a parts car.

thank you!! Sadly ill have to tell the prior owner i cant save it and i look forward to showing you the swap when its done!! Im actually ok with having two motors just in case or to maybe put it in another e30!!

[82eye]

thank you!! Sadly ill have to tell the prior owner i cant save it and i look forward to showing you the swap when its done!! Im actually ok with having two motors just in case or to maybe put it in another e30!!

if doing the stroker you'll be using parts from both motors. if doing the i swap it's a pile of work for not a lot of gain at the end of the day. if the e is in good condition, it'd be best to run it as is and concentrate on other areas like suspension etc.

enjoy the car as is while planning a build and getting the parts together. strip the wreck down and keep what you will use and sell off the other parts to help fund your build.

edit: if resale or collectability is part of the equation - an un modded es will be worth far more than anything stroked or swapped as they are becoming rare. the calculus would be different if it was a regular e car.

[Greekchief]

if doing the stroker you'll be using parts from both motors. if doing the i swap it's a pile of work for not a lot of gain at the end of the day. if the e is in good condition, it'd be best to run it as is and concentrate on other areas like suspension etc.

enjoy the car as is while planning a build and getting the parts together. strip the wreck down and keep what you will use and sell off the other parts to help fund your build.

edit: if resale or collectability is part of the equation - an un modded es will be worth far more than anything stroked or swapped as they are becoming rare. the calculus would be different if it was a regular e car.

I really enjoy Driving it around stock. I have a lot of options now too. I just need to make a plan now. A stock es in good condition on Classic . com goes for way more then what I put into it. I just dont have the stock seats. But really makes me think about what I have now and im really happy I was able to revive an ES like my Father and I used to drive.

Ive found the forum i needed on R3V and I Definity got some work/learning ahead of me. its been an open tab for the last day lol. Thank you again Sir!!!

[82eye]

I really enjoy Driving it around stock. I have a lot of options now too. I just need to make a plan now. A stock es in good condition on Classic . com goes for way more then what I put into it. I just dont have the stock seats. But really makes me think about what I have now and im really happy I was able to revive an ES like my Father and I used to drive.

Ive found the forum i needed on R3V and I Definity got some work/learning ahead of me. its been an open tab for the last day lol. Thank you again Sir!!!

enjoy the car whatever you decide. these cars are a lot of fun with just simple maintenance and minor upgrades. they are extremely easy to mod but are also easy to mod to the point they can be ruined.

read through a few builds before you make any final decisions.

edit: i can tell you what has worked for me on my i car but everyone has different goals. with both motors available you have more options. a stroker opens up a lot of possibility too.

[Toby B]

Having been in a very similar situation a long time ago,
IF
you decide to put the is motor into the 1987,
swap the entire body wiring harness.
Yes, you can adapt the two, but what you end up with
is a mishmash of parts, and eventually you forget what you've done.
It's far easier to just make it electrically a '90, and deal with that.

Likewise, the later cooling system- parts for the
early version have gone uobtanium...

what I would have done differently,
t

[Greekchief]

Having been in a very similar situation a long time ago,
IF
you decide to put the is motor into the 1987,
swap the entire body wiring harness.
Yes, you can adapt the two, but what you end up with
is a mishmash of parts, and eventually you forget what you've done.
It's far easier to just make it electrically a '90, and deal with that.

Likewise, the later cooling system- parts for the
early version have gone uobtanium...

what I would have done differently,
t

Thank you so much for this!! i was really worried about having to repin the 90 to the 87 and TBH i dont want to mess with the harnesses like that. Im wondering if youre familiar with the dashboard as mine is cracked and now i have a uncracked one for the 90. sadly the tinted windows are different

[82eye]

Thank you so much for this!! i was really worried about having to repin the 90 to the 87 and TBH i dont want to mess with the harnesses like that. Im wondering if youre familiar with the dashboard as mine is cracked and now i have a uncracked one for the 90. sadly the tinted windows are different

swapping a dash out is a major pain but is doable. it is easier with the windshield removed if you are contemplating that.
agree with toby b above, swap the entire drivetrain. engine, body harness, transmission, driveshaft, and differential. take it all

[Greekchief]

The current donor is from an automatic, I didnt think that this would be an issue, yet if im keeping the whole wiring system. I might run into some issues. And that goes for my rear lights and such. Am i Unable to swap this motor into mine with the ECU and Complete harness if i Keep my Manual Transmission from the ES?