I've been meaning to post some information about the N52 swap I just finished a few weeks ago. Forgive me for not having pictures, but I have found a some idle time at work and thought I should finally post about this. I'll have to update the post with pictures.
in November of '24 I purchased a 1998 z3, 2.8 manual that needed an engine. the previous owner was making an urgent trip to the hospital and couldn't pull over when the car started to overheat. At the time I had a 1990 325i that I was planning to swap the N52 into, but the Z3 seemed like a good opportunity to get into something different. I had owned the 325i for ~10 years. It was a little rough around the edges, so I was always hesitant to invest much into it. I took a risk, sold the 325i, and bought the z3. This gave me a decent budget to work with for the project.
The engine: N52B30 from a 2010 328i. earlier engines had issues with lifter noise. If I remember, it was resolved sometime in 2009. I got the engine for $200 because it needed a rebuild. It's well-documented that oil leaks from the filter housing can cause the serpentine belt to slip off behind the pulley, getting pulled into the engine through the front main seal and eventually being chewed up by the timing chain. As I tore this engine apart, I realized a full tear down and rebuild was necessary. I installed new bearings and seals which should have been cheap enough, but the N52 uses many one-time use aluminum bolts because of its magnesium block. In the end I could have bought a running engine for less, but rebuilding was a first for me and kept me interested.
Transmission: There were two transmissions used with the N52 powered e9x cars: GS6-37 and GS6-17. I believe the -37 trans was strictly for the 330 cars (with the three stage DISA intake manifold). I used a GS6-17 transmission. They are much more readily available around me, and slightly shorter. I ended up being able to use the original z3 transmission crossmember without modification.
Mounting: This was the easiest part of the project. the E85 Z4 used the M54 and N52 within the same generation. Both variants used the same front subframe, which means the engine arms from a n52 z4 are a perfect fit for earlier cars (E46, E36, E30). This idea came from an E30 forum (r3vlimited) I spent a lot of time on. A few members over there have done some excellent work documenting this swap for the E30 chassis. I used the z3 motor mounts and, as I mentioned above, the z3 transmission crossmember, and the engine and trans fit just about perfect. It seems to sit about 1" further forward than the original M52, but I think this can be addressed with offset motor mounts (not sure about specifics of this).
Shifter: Conveniently, all the GS6-17 and -37 shifter carriers have a length cast into them. after some measurements under the car, I scoured ebay along with realoem and found a shifter that works. I'll have to update about this, but I believe it was a 4 cylinder powered e89 (Europe only?) that had the almost perfect length. It was about 10mm too long but still fit with the rubber insulator on the chassis. I also used the original z3 shift lever but only because it had a shorter ratio - it's almost too short with the 6 speed transmission.
Driveshaft: I used the factor driveshaft and cut about 1.5" out of it. I did the weld prep on a lathe and slowly tacked it together using some v-blocks and a dial indicator to make sure it would run true. I don't sense any vibration while driving so I don't plan to get it balanced.
Exhaust: The factory N52 exhaust manifolds certainly don't look like they were designed to flow well. I ended up factory S54 manifolds with the catalytic converters cut off. This idea also came from the E30 forum. All BMW inline 6 engines have used the same cylinder spacing since the M20 in the early 80s - 91mm from one cylinder to the next. I used the cylinder head flange from the N52, cut off the original manifold leaving about 1" of pipe for welding. I also removed the flange from the S54 manifolds then welded them all together. I'm not expert at this and I ended up with a few exhaust leaks, but overall happy with the outcome. The rest of the exhaust was 2.5" stainless that eventually tied into the factory exhaust upstream of the Z3 primary cats. This part of the project was a bit of a pain. I'm not set up very well in my garage for welding. It works, but isn't anything pretty.
Intake: I used a three stage intake manifold from the 330is. The factory power rating is ~40 hp higher than the 328, so it was easy to justify. It ties into the Z3 airbox that I modified to accept the MAF sensor from the donor car. There was a lot of cutting and gluing of the original airbox that could have been simplified with a simple "cold air" intake.
Power Steering: Thankfully, the e9x cars still used hydraulic power steering. The M52 had the power steering reservoir mounted on the engine, so I had to relocate it to the left side shock tower. Otherwise, connecting the N52 pump to the z3 rack required an e36 M3 high pressure hose (I think the e36 328i used the same one?). The pump side of the hose required a slight bend to fit - something like a 10° twist.
Cooling: Also from the e30 forum, the N52 DME (MSV70 for early cars, MSV80 for later cars) controls the fan rather than the two speed temperature switches used in the E36. This wasn't necessary to incorporate but was a nice to have. I used an E46 fan controller and tied it inline with the Z3 pusher fan. the e46 controller is easy to separate from a fan at the wreckers. It's PWM controlled (digital square wave) and the N52 DME is happy to communicate with it. I put a jumper on the Z3 high fan relay and used this to power the fan. It behaves as if the fan is always powered, but now the DME controls whether it is actually on or not.
The coolant hoses were more of a hodge podge. The upper radiator hose is from an M20 power E30. The length was shortened and tied into the e90 quick connect fitting at the cylinder head. The lower rad hose was original to the N52 e9x chassis, but it was also shortened and flipped around. Hard to describe, but worked in the end. My car is an early 1998 model, so it had the reservoir mounted between the radiator and engine. There isn't enough room for this, so I retrofitted the later reservoir that mounts to the shock tower. The mounting brackets are still available from BMW (and cost $20 for the 3 piece set). The water pump on the N52 is electric and sits at the bottom of the engine, underneath the A/C compressor. I had to run a long length of hose from the thermostat in this area over to the reservoir. The heater is also functional. The heater to reservoir hose is an oem z3 hose, the cylinder head to heater hose is just straight hose connected to the upper radiator hose.
Electrical: This is where the majority of my time was spent: I used the original M52 engine harness and tied it into the N52 engine harness. I spent a lot of time sorting through wiring diagrams to connect the correct wires. The X3 from 2006ish uses a compact relay module with the DME relay in it. I used this to send power to the various wires on the N52 that needed switched DME relay power. This is certainly an over simplification of the process, but I'm happy to share wiring diagrams I used if anyone is interested. It seems the Z3 harness had many changes between engines and years so specifics I used relate to the the harness I was using.
DME: I used the MSV80. MSV70 seems to have more grassroots support for the EWS delete and running as a standalone in other cars, but I have a local programmer/tuner who was able to get the EWS delete to work with some effort. There are several companies online offering this service.
This will be a good enough start. The car runs, drives, and makes smooth power. I don't have power numbers but others with similar cofigurations have dynod at ~270 hp, so power wise this sits in between an S52 (North America) and S54. A fun car with one of BMWs most reliable engines.
in November of '24 I purchased a 1998 z3, 2.8 manual that needed an engine. the previous owner was making an urgent trip to the hospital and couldn't pull over when the car started to overheat. At the time I had a 1990 325i that I was planning to swap the N52 into, but the Z3 seemed like a good opportunity to get into something different. I had owned the 325i for ~10 years. It was a little rough around the edges, so I was always hesitant to invest much into it. I took a risk, sold the 325i, and bought the z3. This gave me a decent budget to work with for the project.
The engine: N52B30 from a 2010 328i. earlier engines had issues with lifter noise. If I remember, it was resolved sometime in 2009. I got the engine for $200 because it needed a rebuild. It's well-documented that oil leaks from the filter housing can cause the serpentine belt to slip off behind the pulley, getting pulled into the engine through the front main seal and eventually being chewed up by the timing chain. As I tore this engine apart, I realized a full tear down and rebuild was necessary. I installed new bearings and seals which should have been cheap enough, but the N52 uses many one-time use aluminum bolts because of its magnesium block. In the end I could have bought a running engine for less, but rebuilding was a first for me and kept me interested.
Transmission: There were two transmissions used with the N52 powered e9x cars: GS6-37 and GS6-17. I believe the -37 trans was strictly for the 330 cars (with the three stage DISA intake manifold). I used a GS6-17 transmission. They are much more readily available around me, and slightly shorter. I ended up being able to use the original z3 transmission crossmember without modification.
Mounting: This was the easiest part of the project. the E85 Z4 used the M54 and N52 within the same generation. Both variants used the same front subframe, which means the engine arms from a n52 z4 are a perfect fit for earlier cars (E46, E36, E30). This idea came from an E30 forum (r3vlimited) I spent a lot of time on. A few members over there have done some excellent work documenting this swap for the E30 chassis. I used the z3 motor mounts and, as I mentioned above, the z3 transmission crossmember, and the engine and trans fit just about perfect. It seems to sit about 1" further forward than the original M52, but I think this can be addressed with offset motor mounts (not sure about specifics of this).
Shifter: Conveniently, all the GS6-17 and -37 shifter carriers have a length cast into them. after some measurements under the car, I scoured ebay along with realoem and found a shifter that works. I'll have to update about this, but I believe it was a 4 cylinder powered e89 (Europe only?) that had the almost perfect length. It was about 10mm too long but still fit with the rubber insulator on the chassis. I also used the original z3 shift lever but only because it had a shorter ratio - it's almost too short with the 6 speed transmission.
Driveshaft: I used the factor driveshaft and cut about 1.5" out of it. I did the weld prep on a lathe and slowly tacked it together using some v-blocks and a dial indicator to make sure it would run true. I don't sense any vibration while driving so I don't plan to get it balanced.
Exhaust: The factory N52 exhaust manifolds certainly don't look like they were designed to flow well. I ended up factory S54 manifolds with the catalytic converters cut off. This idea also came from the E30 forum. All BMW inline 6 engines have used the same cylinder spacing since the M20 in the early 80s - 91mm from one cylinder to the next. I used the cylinder head flange from the N52, cut off the original manifold leaving about 1" of pipe for welding. I also removed the flange from the S54 manifolds then welded them all together. I'm not expert at this and I ended up with a few exhaust leaks, but overall happy with the outcome. The rest of the exhaust was 2.5" stainless that eventually tied into the factory exhaust upstream of the Z3 primary cats. This part of the project was a bit of a pain. I'm not set up very well in my garage for welding. It works, but isn't anything pretty.
Intake: I used a three stage intake manifold from the 330is. The factory power rating is ~40 hp higher than the 328, so it was easy to justify. It ties into the Z3 airbox that I modified to accept the MAF sensor from the donor car. There was a lot of cutting and gluing of the original airbox that could have been simplified with a simple "cold air" intake.
Power Steering: Thankfully, the e9x cars still used hydraulic power steering. The M52 had the power steering reservoir mounted on the engine, so I had to relocate it to the left side shock tower. Otherwise, connecting the N52 pump to the z3 rack required an e36 M3 high pressure hose (I think the e36 328i used the same one?). The pump side of the hose required a slight bend to fit - something like a 10° twist.
Cooling: Also from the e30 forum, the N52 DME (MSV70 for early cars, MSV80 for later cars) controls the fan rather than the two speed temperature switches used in the E36. This wasn't necessary to incorporate but was a nice to have. I used an E46 fan controller and tied it inline with the Z3 pusher fan. the e46 controller is easy to separate from a fan at the wreckers. It's PWM controlled (digital square wave) and the N52 DME is happy to communicate with it. I put a jumper on the Z3 high fan relay and used this to power the fan. It behaves as if the fan is always powered, but now the DME controls whether it is actually on or not.
The coolant hoses were more of a hodge podge. The upper radiator hose is from an M20 power E30. The length was shortened and tied into the e90 quick connect fitting at the cylinder head. The lower rad hose was original to the N52 e9x chassis, but it was also shortened and flipped around. Hard to describe, but worked in the end. My car is an early 1998 model, so it had the reservoir mounted between the radiator and engine. There isn't enough room for this, so I retrofitted the later reservoir that mounts to the shock tower. The mounting brackets are still available from BMW (and cost $20 for the 3 piece set). The water pump on the N52 is electric and sits at the bottom of the engine, underneath the A/C compressor. I had to run a long length of hose from the thermostat in this area over to the reservoir. The heater is also functional. The heater to reservoir hose is an oem z3 hose, the cylinder head to heater hose is just straight hose connected to the upper radiator hose.
Electrical: This is where the majority of my time was spent: I used the original M52 engine harness and tied it into the N52 engine harness. I spent a lot of time sorting through wiring diagrams to connect the correct wires. The X3 from 2006ish uses a compact relay module with the DME relay in it. I used this to send power to the various wires on the N52 that needed switched DME relay power. This is certainly an over simplification of the process, but I'm happy to share wiring diagrams I used if anyone is interested. It seems the Z3 harness had many changes between engines and years so specifics I used relate to the the harness I was using.
DME: I used the MSV80. MSV70 seems to have more grassroots support for the EWS delete and running as a standalone in other cars, but I have a local programmer/tuner who was able to get the EWS delete to work with some effort. There are several companies online offering this service.
This will be a good enough start. The car runs, drives, and makes smooth power. I don't have power numbers but others with similar cofigurations have dynod at ~270 hp, so power wise this sits in between an S52 (North America) and S54. A fun car with one of BMWs most reliable engines.
