3-Series (E21, E30)Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.
Wouldn't do much, with out the larger head ports the flow would actually slow down, think of it like having a 2 1/4" exhaust going into a 1 1/2" muffler. Plus the injectors would be spraying right on the edge of the intake port and not into the port itself, and to make matters worse you'll have a little pocket at the head where the bottom of the intake runner is larger than the port where fuel and/or oil can collect causing the motor to desiel (the car sputtering after you shut the car off).
So long as the last 3 digits of the M30 AFM are 027 it should work just fine in the 325e/es, however an adjustable fuel pressure reg is needed as the larger M30 AFM will make your motor run a tad lean.
To use the M30 AFM correctly in the 325I motors you'll need to transfer all the M20 guts to it. Not very hard but a delicate pain in the ass, pluss the screws don't want to come out (BMW screw glue really works).
All in all, the larger M30 AFM will give you about 5hp.
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