Firstfives.org

Is there any difference between the M30 motor
in this model and the one in a 530i? Do they have the same ECU?

A Euro 728 would have a higher compression 2.8 engine, probably 9:1 instead of the 8.3:1 of a US spec 530i. About the same power but a touch less torque. The euro car might have a hotter cam and would have a different curve on the distributor, and of course would not have come with all the smog equipment that was on US cars. Different ECU, but I bet you could interchange them and they'd run just fine. Very similar engines, but not exactly the same.

Mike W. wrote: ↑Sun Oct 23, 2022 12:41 pm A Euro 728 would have a higher compression 2.8 engine, probably 9:1 instead of the 8.3:1 of a US spec 530i. About the same power but a touch less torque. The euro car might have a hotter cam and would have a different curve on the distributor, and of course would not have come with all the smog equipment that was on US cars. Different ECU, but I bet you could interchange them and they'd run just fine. Very similar engines, but not exactly the same.

For 1980 model year in Europe the e23 7 series went completely fuel injected. in 1977-79 they had the single carb 728 & 730, and the injected 733i (3.2L). For 1980 it was 728i, 732i, 735i & 745i.

Euro 1980 528i/628CSi & 728i all used a 184 hp M302.8 with 9.3:1 comp ratio. The earlier Euro carb engines were 9.0:1. The higher comp ratio, and weight cutting program (thinner glass, hoses, panels etc) was all to boost fuel efficiency in the wake of the 2nd fuel crisis. Tachs even had a green segment, in the lead up to the pending swinging fuel economy meter needle.