2.5 lump into a 318i

[alockton555]

Hello all

I have just got an E-reg 318i with a dead engine, and I'm planing to put a 2.5L engine in it to use as a trackday car. Now I appreciate this is not quite so ambitious as some projects, but I'd very much appreciate any comments or experience? I'm not sure of the variant of engine I have yet, but it has drums on the back if this helps?

From reading around on the forum, seems I need the gearbox and LSD and exhaust off the 325, but what about electrics - is it just a case of swapping ECUs or would the loom need swapping? Am I likely to need any other parts or surgery? Would the fuel system cope? Also, can I easily fit 325i brakes? Seems like the advice is to get a complete donor car? (only problem is where to put it!)

Any comments or info much appreciated.

Thanks, Aaron

PS Anyone want any of the then interior let me know!

[nav786]

firstly its much easier to get a donor car. the bits you will need are

engine & box
ecu and loom
radiator and expansion tank
prop
Brakes (rears will have to be converted to discs)
Diff
and suspension.

thats all i can think of at the moment. oh and the power steering pipes will need to be changed as they are too short.

[alockton555]

Hi there, thanks for your input. It seems inevitable we will have to find the space for a donor then (and a place to put it!). You say the diff, prop and 'box will have to be changed. I assume this means a hoist / pit will be essential (not used to this RWD malarky!)

In terms of the electrics, does everything basically have to be swapped or is it just the wiring involving the ECU and sensors?

Is the disk conversion difficult, i.e. any extra bits or will they go straight on. Or do the driveshafts and hubs need swapping as well?

You say suspension as well, presumably this is to cope with the increased performance, rahter than a physical necessity to fit the new parts?

Many thanks for your comments, Aaron

[Turbo-Brown]

You can get the engine and box out using just some big axle stands if that's any help?

[bennyboy]

i am looking to do the same conversion. when you say 'replace the loom' is this just the loom under the bonet? i am not going to have to take the dash out am i?

[Brianmoooore]

i am looking to do the same conversion. when you say 'replace the loom' is this just the loom under the bonet? i am not going to have to take the dash out am i?

There's a big plug and socket clipped to the bulkhead, just inboard of the fusebox, known as the C101 connector.
This connector is the only connection normally between the engine and body looms on an E30, except for connections to the battery +.
The engine looms are entirely under the bonnet, except for a large bunch of wires going through the bulkhead on the drivers side, going to the ECU. There may be a couple of small sockets beside the ECU, which in most cases are unused They are for things like increasing the idle speed on aircon cars, and IIRC there is a connection to one of them on some autos.
When you remove your doner engine, leave the electrics connected to it. Undo the C101, disconnect the ECU, and feed the ECU plug back through the bulkhead. Dissconnect a few earths and battery + connections, and take the engine and box out complete with electrics.

[Brianmoooore]

i am looking to do the same conversion. when you say 'replace the loom' is this just the loom under the bonet? i am not going to have to take the dash out am i?

P.S. Complete dash removal and replacement is reasonably easy on an E30. At least it is the second time you do it.

[bennyboy]

the engine loom is the only bit i need to change then?

[alockton555]

Thanks for all the electrical info, very useful.

Just wondering whether a new gearbox is necessary because the old one won't physically attach to the 2.5 engine, or because it won't handle the torque. In other words, could you physically swap just the engine, and hope for the best that everything else would survive a couple of hundred miles...?

Aaron

[oze30]

Do you need to alter the prop shaft? Im looking at doing this to a 316/8 touring. Is there anything else that I would need?

[Brianmoooore]

Do you need to alter the prop shaft? Im looking at doing this to a 316/8 touring. Is there anything else that I would need?

325 prop is a different length.
For 318 to 325 to work reliably, you need a medium case diff to replace the small case one, different front struts and springs (325 struts are larger diameter, and stronger springs needed for heavier engine), and you will need modifications to the left hand inner wing for the rad header tank and 325 air filter/air meter.