Mid-'80's M30 conversion

[Dash01]

I have an chance to buy an '85 E24 635csi, for cheap. This because the HG went south, the engine overheated, and the head is probably warped (or worse).

The car has a manual transmission, which is desirable. OTOH, M30 enigines of that vintage only put out ~180 hp, whereas the later M30 engine on our E34 puts out ~210 hp.

If I wanted to get more power by converting to the latest version M30, what would be needed?

Are there other, even more powerful engines, that would simply bolt to the old manual transmission in this E24?

How about chucking the AFM/MAF as Martin in Bellevue did, to upgrade the intake system?

[Jeff N.]

..they do this stuff all the time.

Here's my general understanding. Our M30 is a general bolt in to the E24 chasis. Some stuff like motor mounts etc. need to be swapped over but the engine will drop in and bolt to the tranny.

You need to swap in the later model engine wiring harness and ECU (Motronic 1.x vs our motronic 1.3). I hear this is a bit of a PITA as the our cars have the ebox under the hood and the E2x's have them in the cabin. You need to extend all the wires in the engine harness.

So..mechanically, I think it's pretty easy. Electrically, not so easy.

I might be simpler to toss a TCD turbo on the car vs. go to all the trouble to swap.


I have an chance to buy an '85 E24 635csi, for cheap. This because the HG went south, the engine overheated, and the head is probably warped (or worse).

The car has a manual transmission, which is desirable. OTOH, M30 enigines of that vintage only put out ~180 hp, whereas the later M30 engine on our E34 puts out ~210 hp.

If I wanted to get more power by converting to the latest version M30, what would be needed?

Are there other, even more powerful engines, that would simply bolt to the old manual transmission in this E24?

How about chucking the AFM/MAF as Martin in Bellevue did, to upgrade the intake system?

[Alexlind123]

The valves are larger on the M30b35