Motor swap (87is into 91i)

[svn2002s]

Planning a motor swap this long weekend. Is this a straight motor swap or do I need to bring some of the electronics from the donor car.

[damith]

motor swap

there's much more info about this topic in e30tech also. u might want to chk it also.
and GL with the swap

[porsche gt1]

wow, never really heard of putting a M20 in place of a m50. Why this change?

[tonytony]

91 325i still has the m20, unless the OP actually has an m50.

[svn2002s]

I just got a 91 with a blown engine plus an 87 donor car. Just need to make sure that electronics, harness and other related shit that I don't know would be ok.

[Rocla]

I just got a 91 with a blown engine plus an 87 donor car. Just need to make sure that electronics, harness and other related shit that I don't know would be ok.

If both cars have m20, why not keep all 91 injection pieces and just replace the engine?

[redhatpat]

If both cars have m20, why not keep all 91 injection pieces and just replace the engine?

Agreed. This would be the simplest thing to do. The engine should be identical mechanically.

[svn2002s]

That's the plan, I was just wandering anything on the electrical side.

[Axxe]

That's the plan, I was just wandering anything on the electrical side.

You need to use the '91 wiring harness. ECU is interchangeable, pick the one that is a 173 :D.

[Keith M]

The main differences are: (this is based off my motor swap - 88 motor, 89 harness into an 87)
The FI on the 87 is wired directly from the main harness, On later models, they use the C171 plug between the harness and the injectors.
The plug for the O2 sensor is different.
There were several extra wires where the harness meets the ecu.

Keith