E39: M52B25 to M52B28

[jayray 0]

Hi there, I've no experience with the compatibilities of DME and EWS systems on these cars and I'm looking to absorb some wisdom

I've got two E39s, both '95 or '96, a crashed 528i japanese import, and a high mileage NZ new 523i. The 523i was bought with a blown head gasket, with the intention of replacing the motor with the B28 from the crashed car.

We were intending on using both the engine and box from the 528, but that means the car changes from ZF to Jatco box. Is there any preference for which box is better, and is replacing the high mileage ZF for the lower mileage Jatco worthwhile?

Lastly, what difficulties are there for all the electrical components to play together nicely? If we use the ECUs from the donor motor and box, do we need the donor DME and other anti-theft parts as well?

Thanks in advance

[allan 295]

Hi Jeremy

No experience with the e39 range but have done a similar thing on a e46 removed a n42 motor and fitted a M54B25. On that I used all of the M54 electronic parts and keys you will more than likely have to do the same with the M52 motor and gearbox which ever one you decide to use. The ews on those I believe is only series two so not as involved as the 3.2 series. Also check out which system each car has for your remote entry if fitted ie infrared of radio. As this coursed me some problems when it came to locking the car their are ways around this. As I found out the motor set from the donor car was infrared red, Japanese import but the original car NZ new had radio to over come this it involved using the coding stored in the ews and transferring it onto new transponder chips in some new keys. Their may be easier ways to over come this but this is what worked for me. The gear box side of things autos I presume the parts cat shows them as A5S310Z or A5S300J for both the 532 or 528 so the control unit for which ever box you use will have to be put into play. The only thing is will the ZF controller talk to the DME of the 528 or vise verse with the jatco. Some research work might be required their. The mechanical swap should be straight forward if you use all the parts retaining to the 528 no doubt some of the 523 parts will be the same any how so just us the best were applicable. Best of luck and let us all know how you get on with it.

[Allanw 1072]

On such an old car, and for a fairly basic upgrade, you can probably get away with just fitting the bigger lump and run the 523i ecu as is.

It's NOT the right way to do it, but it's not like you're fitting the V8 or increasing the capacity by a large percentage (it's only going up 300 cc's, and under 20kw from memory).

I know it's been done before, and works well enough to drive - BUT DO YOUR OWN RESEARCH on it - you don't want to end up with a complete dog.

I don't know, but it may lean out a bit at high RPM, as the 523i may run smaller injectors or something, but the AFM and o2 sensors will probably overcome the majority of lean problems, except the extremes.

also, be aware that it technically DOES need a cert, as the capacity is increased.

Swapping over the bits from both cars "properly" is a LOT of work for very little gain.