Having run an M5 for a few years, which, sadly, eventually became uneconomical to repair when the engine chewed a second set of bearings and a couple of con-rods, I've been thinking lately of getting back to the relaxing torque of the 5.0l V8. With prices for E39 M5s at an all time low (and still falling), but with a need for an estate, I'm pondering on getting a bit of a snotter and swapping the drive-train into on of two cars: an e46 3 series touring or an E39 touring. The idea would be to buy the donor car and the target car at the same time, then do the swap.
From, admittedly limited, research, I gather that the swap into an E39 should be fairly straight forward: the dashboard, keys, locks, ECU, etc... would all swap straight over and mechanically it would be very simple.
BUT, having had an M3 previously, the idea of an E46 with 400 ponies is very attractive. Mechanically its a bit more of a challenge and from the wiring/electronics view-point its also going to be more of a challenge, but I figure that if I take my time about it its certainly do-able. I can fabricate engine mounts, new headers, gear-box mounts and so on, so the actual fitting isn't to daunting, but I do have concerns about the electronics.
So I guess my question is: is it possible to drop an S62 into an E46 shell, and get it working, with the majority of the electronics also working. I know that the dashboard would need some serious mods to take to the E39 gauges, but assuming I can do that what other pitfalls are there?
I'm wondering if the engine would even fit. The front of the car would be very heavy and the handling would probably be horrible. If you are going to go to all that trouble and deadset on an E46, then consider boring out the engine so you get better low end torque. That, or put it in the E39 touring.
Why wouldn't you just get an E39 M5 in good condition and enjoy it? I would think you would have more problems trying to swap an engine than just properly maintaining the car how it was designed.
I've currently got an E46 Touring, and its been a god-send in terms of taking the dogs out and carrying stuff - just today I collected a 300l water cylinder, that would never fit in a saloon (nor on the roof).
Funnily enough, the E46 3l diseasel engine weighs MORE than the V8, and that handles just fine. Dimensionally it will fit, although the ancillaries will take a bit of work and the steering column might be an issue, but mechanical stuff is "easy" to sort out, its more the electrics I'm concerned about.
The S62 in an E46 has been done many, many times. Board member "Silent" has one example.
And there are at least a couple of M5 touring conversions. One on this side of the pond (Hartge M5?) and one on your side of the pond (board name escapes me). And of course, there is the one off done by BMW itself.
An E46 S62 would be WIN! While the suspension may be able to handle the added weight, the moment of inertia changes dramatically. Make sure to balance out the rear of the car, this is also one of the reasons why I refuse to consider muffler delete (weight reduction in the lower rear). Looking forward to your builds, it will be an EPIC "conundrum" indeed.
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Favorite Quote: "Understeer is when you hit the wall with your front end. Oversteer is when you hit the wall with your back end. Horsepower is how hard you hit the wall. Torque is how far you move the wall when you hit it. "