E39 with S52...??

I'm looking for a replacement E36 M3 (sedan, hopefully this time) and found this:

S52 swapped E39

I thought E39's were: 1. Heavy 2. More powerful than S52 if you got the 540

I'm questioning why you would do this swap? Fuel efficiency? The V8 (non-m5) models make 282hp while the S52 only makes 240.

Seems like a bunch of work for not much reward, but I'm interested in your thoughts.

Well a couple reasons probably.

1. The I6 E39 uses a steering rack rather than a steering box (used in the V8 cars for packaging reasons I think).
2. The V8 (4.0L) can be expensive to maintain.
3. The V8 in the M5 is uber expensive so you wouldn't go that route, you'd just get an M5.

I like the idea but you're right, it isn't going to be a rocket ship, but it will be a fun car.

The 2.5/2.8/3.0/3.2 engines share a common architecture and many components, with the S52 overbored for extra displacement. The 3.2 is an easy swap (only need new block/heads/ecu, everything else is retained) and posts notably better numbers than the 2.8 which originally appeared in this car. If the original engine blew, it's not a bad upgrade.

Why - Easy upgrade for a 525, 530, etc.

But yeah - it will be slower than the E36 M3 or the E39 540.

E39s are heavier than the E36 by a bit but if it was a 525i to start with then the wiring harness/exhaust/trans and all the bits would work without changes. A true bolt in. Swapping the V8 in is more work for little gain. You need a whole donor 540. There are more tuning options at better cost than the V8 too. An S52 with cams, maf, injectors, headers and software will make 280-300 at the crank.

I wouldn't touch that particular car with a ten foot pole but I do like the idea of swapping an s50b32 into an e39. I've considered doing just the s50 cams and an obd1 intake for a nice little bump in power.

If I was going to bother with a swapped E39, it would be an LSx.

DILYSI Dave wrote: If I was going to bother with a swapped E39, it would be an LSx.

That's what confused me about the whole thing. I can't imagine the s52 being that much cheaper than an LSx. But I've never priced either. I suppose it may be the "plug n play" nature of sticking with the BMW. For my PITA, time, and $$, I'm putting an LS in there.

yes.. it is the plug and play option that makes it easier and better.. maybe an S54 instead?

I have impure thoughts about swapping an S54 into my 525i. A spiritual successor to the E34 M5 (I'm quite devoted to the BMW I6). I imagine it's rather more complicated than the M52->S52 swap, however.

Hi,

New member here, own a 2002.10 E39 525i and I just went full retard and bought a rebuilt S50B32 engine + auxiliaries + radiators (coolant, oil) to do a swap.

Would appreciate your advice & input on this swap, what to consider, what pitfalls there might be, etc.

Thanks in advance!

Paul

Hi Paul, sounds like a cool build! If I were ever to have another E39 I would probably seek out an earlier 528i sport package and do the same swap.

The only pitfall that comes to mind off the top of my head (more than 6 years removed from my last E39, FWIW) is that I think the E39 525i used MS43 engine management while the S50B32 used MSS50. I think that puts you down the rabbit hole of ECU and larger wiring harness differences that could be a pain in the butt to resolve. There's always a way but I think the earlier E39s (528) are more closely related to the E36 electronically while the later E39s (525/530) are more closely related to the E46 which might add difficulty to your swap.

Either way, I could be wrong, and good luck!