[Fireball5657]

Hey all! I've owned a few BMW's over the last few years, but I never have started a build thread. Typically I buy cars that were well sorted and just needed routine maintenance, and I've never owned them long enough to modify them, but this time will be a little different. I already have a nice well sorted BMW to be my daily driver, my jack-of-all-trades F10 535i. This time I wanted a proper project, so here we are!

Meet my third E9X car and my fourth BMW overall: my 2010 328i in Alpine White! It's a stripped out spec for a US car, the only options it has is the dakota leather and the automatic transmission. Gotta say, it's weird pulling a lever to move the seat in a fairly modern BMW! This one has just 86K miles on it and was only $1500, but there was a catch...



This is a SULEV car, unusual since I live in Oklahoma, a non-SULEV state; and so that means this came with the N51. I knew a little about the N51, enough that I never wanted to own one, but it didn't really matter that this car had the N51, because the engine was totally blown! The previous owner said the car just made a loud bang, dumped all the oil out, and sounded like hell. It had to be trailered home, here's a pic behind my truck.



I knew that I didn't want to put another N51 back in this car. With the lower compression ratio and the thinner connecting rods, among other changes, I'd rather not compromise and just get a full N52. There wasn't a lot of information on N51 to N52 swaps, some say that it wouldn't work, and some claimed to have done it successfully without a single change to the DME, but it isn't a heavily documented job.

I found a N52 locally from a BMW parts seller, it came from a 2006 530i and had high mileage, but the engine looked clean enough and I trust the N52 to last 300k or even 400k miles, it's been done and documented before!




First step was to get the N51 out. While my parents have a nice two post lift at their house that would be perfect for swapping an engine, I worked night shift and they work day shift, so I decided to do it in my garage instead and pull the engine through the front of the car. It was fairly easy to get it out, the worst part was getting the exhaust manifold and oil pan to clear the subframe. Eventually I got it out, and I got a chance to see what exactly gave up on this N51.




Well, that was the culprit, that's the bottom half of cylinder 1's connecting rod. The bearing cap broke in half and split the connecting rod, which shot itself into the oil pump, breaking the chain, and broke through the oil pan and the block itself. Pretty gnarly.

But now it was time to get the N52 ready for battle. Again, I didn't want this car to go back in completely stock. The N51 comes with the three stage manifold and the DME is already set up to use it, so with the higher compression ratio of the N52, that's bound to make more power than the stock 328i's 230hp/200tq, but I wanted more. Headers were another easy one, I've had good luck with cheap headers in the past through friends' builds, so I bought some cheap headers from a no-name company. Sure, AA headers would be better, but is it really worth 3x the money?? That's a subjective question, but I was willing to take the risk, those headers would cost me half of what I paid for this car! MILV's were in stock, but were just a liiittle too much money for me. I figured headers and the 3 stage manifold was a good start for power. If I want more, it's easy enough to add MILV's.

So now it was time to swap and replace. I swapped all the accessories and all the electronic bits from the newer N51 to the older N52. I also took care of the big three oil leaks, valve cover, oil pan, and OFHG. All jobs I've done on my previous E9X's, and all jobs that are MUCH easier when the engine is out of the car haha.

In my excitement, I didn't have any pictures of the engine on the stand, but over the course of a week, I had it cleaned and ready to get put back into the car. I bolted the GM auto back to the engine and worked on getting it put in. Easier said than done, putting the engine in was much more frustrating than getting it out, but after a few hours, I got it in and mounted up.



Within a week or two, I had everything plugged back in, all the hoses connected, and the fluids filled enough to finally turn this engine over and start it. Unfortunately the battery died as it was cranking, so I charged it for a bit and then tried again. After a long crank, it fired up! It smoked like a train, it sounded like the exhaust wasn't even connected, and it had a very rough idle, but it was running! (I should add, all of these went away after running it for a bit, these are not current issues!) Had a few leaks to take care of, a power steering line had popped off the cooler, the upper radiator hose had a small leak in it, and I didn't push the hose for the coolant reservoir all the way on, so it drained about $40 worth of coolant onto my garage floor. My bad haha. After fixing all of those leaks, I filled the transmission with Dexron 6, topped the power steering fluid up, topped the coolant up, and finally took it for a drive!

Here's the car just outside of my garage, right after I got it on the ground for the first time in months.



I took it on its maiden voyage, which was to the tag agency so I could get it registered and get rid of the black tag. After that, I spent several hours and drove over 100 miles in that car, just to see how it was with the N52. To my surprise, the DME had no issue with the N52, it runs it just fine and isn't throwing any codes, so an N51 to N52 swap is absolutely possible and 100% works, for anyone looking to a similar swap. I fell in love with the E9X chassis all over again. I haven't owned one since August 2023, when I sold my last E90 to get my F10, and driving this car around felt even better than I remember. I don't need to gush about the E90 to you lot, there's a reason we're all on this forum , but it was so refreshing after having driven my F10 exclusively for nearly two years. Despite that car being a full M-Sport, it's just a bigger car and it's a completely different class and generation of BMW, they're just not comparable.

The N52 I bought proved to be a great engine, despite the higher miles and unknown service history, it ran great and felt strong. No lifter tick to speak of and no oil consumption issues in the 250 miles I've driven since I got the car back together. As far as power goes, it's definitely more potent than my previous E90's. I recorded a 0-60 time of 5.8 seconds without any brake boosting, that's just pedal to the floor on a dry flat road. Those numbers are closer to a manual 330i than a auto 328i! It feels much stronger than any 328i I've ever driven and sounds great on top of that, I couldn't be more pleased, especially since I haven't even tuned it yet. It really feels like the sweet spot for the N52, it's a seriously zippy little car. Honestly? I think it could almost keep up with my stock N55/8HP-powered 535i in a straight line, and it'd blow it away in the corners!

Of course I can't leave well enough alone, since the car has gotten back on the road, I've retrofitted the sport steering wheel, a 335i cluster (has oil temp instead of MPG), and folding rear seats. All are fairly easy retrofits and all jobs that I've done before on my previous E90. I also changed the daytime running lights from the high beams to the angel eyes, which is how it should've been from the factory!




And that's how it sits now, three days after first startup. I still have some things to do, the vacuum hose for the brake booster is cracked, so I'm rolling with manual brakes at the moment. The underbody shields are still not on, and the exhaust has a slight leak where the headers meets the pipes. All should be simple fixes I can worry about later. It also needs to be taken into the dealer for the Takata recall, the sport wheel airbag I had on had was from 2016, but it isn't the latest version. It'll need a tune at some point too, I'm sure the fuel trims are all out of wack with no primary catalytic converters, though I don't notice it at the moment.

As far as modifications go? I'd like to find a nice set of style 162's, I'd like a slightly louder muffler, and manual sport seats would be a dream come true. But that's pretty much it, I'm in the honeymoon phase right now where all I want to do is drive it and enjoy it after spending three months wrenching on it.

I'll get better pictures soon, being on night shift means that my most active time of day is when it's pitch black outside, so it's hard to take good pictures at the moment!

[Fireball5657]

Got new headlights installed! LED turn signals and angel eyes, and the headlights and fog lights have that blue coating which makes it look more white. No errors or hyperflashing with the LED's, which I was a little worried about.



I've driven it about 800 miles since I got the engine installed, so it'll be time for it's first oil change soon. I added some atf to the oil in hopes that it'll help clean out the sludge, it's worked for me in the past. Engine still pulls strong and the transmission is about as smooth as these GM's get. I do have a squeak in the suspension over bumps, and I've noticed that the front struts are leaking and the bump stops are completely disintegrated, so I guess I'll need to replace those fairly soon.

Other than that, no new problems have popped up. It does need to be washed, but I'll worry about that this weekend. We've had a lot of rain here over the last week or so. It's great being back in an E90 again!

[RealJ22]

Great work! I recently thought about doing the same thing. My N51 is healthy still, so we will see!

Keep posting updates!

[MadJoe]

Any semi-long-term updates? How is it running? Still in love with it? Any new mods to report?

Come on, don't let this thread die!

[Fireball5657]

It's been a while, not much to update since I haven't done much to it! My 535i has been a continuous headache, so it's nice having the E90 around. Not to say that they're isn't anything to do. The heater core needs a flush and it could probably use a new starter. But I plan on tackling both of those problems at the same time I finish my performance modifications.

And on that note, the three stage manifold has been fun, but I've got a bad DISA, so instead of paying $600+ for a new pair, I managed to get my hands on an N54 manifold with the throttle body! Even with the price of the manifold and all the parts to adapt it to the N52 (intake hose, PCV heater adapter, offset bushings), it'll still be cheaper than a single OEM DISA valve, and I don't have to worry about it breaking in the future. I also intend on ordering a set of MILVs fairly soon, and a tune (likely from 22RPD) to tie it all together. I wanted to have it all done sooner, but the F10 keeps draining my car funds .

So we don't have a lot of fun driving roads here in Oklahoma, especially where I live in the middle of the state. I've had the itch to enjoy the car on a road that wasn't just a straight line (since that's not a 328i's strong suit), so I took a trip out to the south east recently to a road called the Talimena Scenic Byway. I've taken the F10 there before, but I haven't driven any of my E9X's out there yet. Unfortunately I happened to go on the cloudiest day we've had in a while, there were some spots that were somewhat clear, but for most of it you couldn't see more than 50 feet ahead of you!

Overall the car did good, but it really helped me pick out what I do and don't like. My biggest complaint is that GM transmission, it's not doing anything weird, but it's nowhere near as fun as a manual or even the F10's ZF 8HP. If I keep this car long-term, I really want to look into a manual swap (or at least paddle shifters!). The engine is also down on power, this was before I knew the DISA went bad, so that definitely played a part in it, but it definitely could use some more power when exiting a corner (hence the MILVs). Suspension and steering I have no complaints on, it was comfortable on the highway and solid around the corners, the car always felt like I could've pushed it harder, though I wasn't trying to test my luck on the wet and cold roads.

Anyways, I'm not much of a photographer, so pardon the mediocre pictures haha