[bosna1973]

Is it possible to instal engine n45b20 instead n46b20

[bmwlover]

Possible but you need to change computers and many other things.

[Beard]

Hello.
It is certainly possible to replace.
If your engine is 2 liters?
You will have to change the motor wiring, DME unit, Reset engine hours in the DME unit, change the power class in CAS, Synchronize CAS - DME. Replace exhaust system (catalyst and exhaust pipe) Rewrite EGS program (or replace)???
If your engine is 1.8 liters?
Then there will be less change.
Your exhaust system will remain the same.
And don't forget!!!

The main pair (reducer) is different in all cases!
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[bosna1973]

Looks like not worth, I have engine with just 160k km but someone was already changing head bolts and two bolts on engine block treat is striped