E84 N20 to N55 conversion.

AshE84 · 08-19-2022, 02:37 PM

Hi all, before I start getting all the "just buy the car with the engine in already" comments I'd like to make it clear that in the UK it doesn't exist the biggest we can get here in RHD is the 2.0l N20B20A.
I have a 2013 E84 Sdrive20i with the 6 speed manual gearbox. I recently developed a misfire on cylinder 4 of my engine which after some diagnostics i believe to be the cylinder rings failing. due to this I find myself in the position of either stripping and rebuilding the N20 with up rated parts (because I wanna run about 350hp) which will cost a few grand and may not be the most reliable once done, or what I'm hoping to do, is swapping the engine for the 3.0l N55. From what I can tell it should be doable. I believe the the gearbox fits but I'm not sure what clutch and flywheel I'd need. I know the engine itself will fit as the US and Germany have models with the engine fitted from stock so things like engine mounts/ Rad lines, and Ect can be found rather then need to be custom made.
The main thing I'm unsure about is, would I just need to swap ECU's or would I need to change other computers to get the engine to run and for the Idrive and OBD to work along side as if it came from factory fitted. My idea was to buy a donor car and swap the parts I needed but if all i'd need is the engine and ecu then i may find them cheaper than an entire donor car.
Any advice would be appreciated TIA.

wheela · 08-20-2022, 08:59 AM

Sounds like a cool project! I can't help much with the details, but from reading other peoples' engine swap threads, I believe there will be a lot of coding involved to get the new DME communicating properly with all the other modules in the car (I know squat about coding). Also, I didn't know any e84's with an n55 came with a manual transmission (honestly, I didn't realize any e84's at all could be had with a manual, learn something new every day). I'm sure you already know, but e9x or e82 are extremely similar and may work as donor cars.

Gamb1t · 08-21-2022, 01:56 PM

It's not just the engine, you would have to swap out the turbo and whatever the exhaust parts. ECU is likely different. There is a PDF that is named BMX X1 Complete Vehicle that outlines the component differences. It will be quite an endeavor to swap it. Though being manual and non-Xdrive may simplify a bit.

Based on your info, your N20 s20i might be a detuned version of the North American x28i's 241hp N20.

08-19-2022, 02:37 PM	#1
AshE84 Registered 0 Rep 1 Posts Drives: BMW E84 X1 Sdrive20i Join Date: Aug 2022 Location: Telford, Shroshire iTrader: (0)	E84 N20 to N55 conversion. Hi all, before I start getting all the "just buy the car with the engine in already" comments I'd like to make it clear that in the UK it doesn't exist the biggest we can get here in RHD is the 2.0l N20B20A. I have a 2013 E84 Sdrive20i with the 6 speed manual gearbox. I recently developed a misfire on cylinder 4 of my engine which after some diagnostics i believe to be the cylinder rings failing. due to this I find myself in the position of either stripping and rebuilding the N20 with up rated parts (because I wanna run about 350hp) which will cost a few grand and may not be the most reliable once done, or what I'm hoping to do, is swapping the engine for the 3.0l N55. From what I can tell it should be doable. I believe the the gearbox fits but I'm not sure what clutch and flywheel I'd need. I know the engine itself will fit as the US and Germany have models with the engine fitted from stock so things like engine mounts/ Rad lines, and Ect can be found rather then need to be custom made. The main thing I'm unsure about is, would I just need to swap ECU's or would I need to change other computers to get the engine to run and for the Idrive and OBD to work along side as if it came from factory fitted. My idea was to buy a donor car and swap the parts I needed but if all i'd need is the engine and ecu then i may find them cheaper than an entire donor car. Any advice would be appreciated TIA.
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08-20-2022, 08:59 AM	#2
wheela Captain 280 Rep 696 Posts Drives: 2015 BMW X1 35i M-sport Join Date: Mar 2021 Location: Twin Cities MN iTrader: (0)	Sounds like a cool project! I can't help much with the details, but from reading other peoples' engine swap threads, I believe there will be a lot of coding involved to get the new DME communicating properly with all the other modules in the car (I know squat about coding). Also, I didn't know any e84's with an n55 came with a manual transmission (honestly, I didn't realize any e84's at all could be had with a manual, learn something new every day). I'm sure you already know, but e9x or e82 are extremely similar and may work as donor cars.
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08-21-2022, 01:56 PM	#3
Gamb1t Major 598 Rep 1,343 Posts Drives: 330i,X1,Z4,Solstice GXP, RX-8 Join Date: Aug 2015 Location: Canukistan iTrader: (0)	It's not just the engine, you would have to swap out the turbo and whatever the exhaust parts. ECU is likely different. There is a PDF that is named BMX X1 Complete Vehicle that outlines the component differences. It will be quite an endeavor to swap it. Though being manual and non-Xdrive may simplify a bit. Based on your info, your N20 s20i might be a detuned version of the North American x28i's 241hp N20.
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