BMW E21 24v Swap How to

Build007 1983 BMW E21 320 S52 295

The E21 has been really coming into it’s own over the past few years.  With the rising costs of 2002 and E30s the once forgotten about E21 is now getting a bit of attention.  One area the E21 lacks is in the power plant department.  While europe got the m20 powered 323 over in the US the only option was an under powered m10.

Well this wap changes that greatly.  With our mounts you can install any 24v 6 cylinder into the E21.

We are working on a more indepth how-to to match our M42 2002 how to but until then here is some limited information.

At minimum you need a E34 m50 front sump oil pan to go along with any of the M50/M52/S50/S52 engines.  The M54 options will work as well but require a custom oil pick up tube.


The 24v engines came in both OBD1 and OBD2 options.  Both of these can be used in a E21 with very similar wiring setups.  Below is some information on the wiring.

E21 C101 PinE36 x20 PinFunction
123oil presure light
313fuel pump
525alternator charge
621DME Switch Power
822 - OBD2 OnlyPower to diag power
13Wire direct to coolant sensorCoolant temp
1520 (will need adapter)Tach
no connection8 - OBD1Check engine light ground
no connectionx6031 - 1 - OBD2Check engine light ground