BMW E30 M50 Swap information

Published on Saturday, 18 January 2014 Written by kratzer

 

- Engine

Complete M50 engine of an e34 or e36 with accessories and wiring harness. 

M50 engine data at the following link: M50 information

Engine mounts arm of a 6 cylinder E36.

If the engine is from an e36 the oil pan and pickup tube have to be changed by the ones of an M50 E34. They have to be changed because in the e34 the oil sump is in the front part (like in the e30 engines) and in the E36 the sump is in the rear part.

E34

Oil pan M50 e34

E36

Oil pan M50 e36

The engine mounts have to be changed by the ones of an e28/e24 M30 or by specific ones for an E30 M50. Depending on the used brake booster it will be necessary to add washers or spacer to lift the engine so that the brake booster does not touch the intake manifold.

At this point the next steps depend on the specific e30, the engine donor, and what we exactly want to do since there are several options. 

For the throttle cable it can be used the one of an de M50 E34, M42 or M20.

 

- Cooling System

The radiator can be changed or not depending on the car and what we want to mount. 

The radiators with built-in expansion tank of 440 mm can be used (from an e30, e36 or e34) but not the ones of 380 mm since the coupling from the driver side would be too close to the power steering pump and its belt drive. The radiators with external expansion tanks from M20 do not give any problem.

With these radiators there is little room left for the fan clutch.With a radiator from a 28/e24 M30 of 575 mm it is obtained more space between the radiator and the engine to place the fan clutch. To obtain some more room the fan blades can be mounted inside the fan clutch and trim them up in engines with vanos so that they do not graze.

Electric fan: If a fan clutch is not used or to reinforce the cooling system, an electric thermo fan can be installed with two speeds. The e30s with air conditioning have an electric thermo fan that can be reused.

 

- Gearbox and driveshaft

There are quite a lot of options since many gearboxes are compatible from different generations of BMW (both, in 4 and 6 cylinders).


M20 gearbox: It can be used but it stands rotated several degrees so it is necessary to make modifications in the transmission crossmember, mounts and shifter linkage. With this gearbox it is not needed to modify the driveshaft.

M42 gearbox: It can be mounted without any problem in with an M50 engine but the gearbox will be displaced towards the back so that it is necessary to cut the driveshaft and shifter linkage.

M50/M52 gearbox: It has a different gearbox ratio that the e30 gearbox so the differential ratio would be very short. The differential has to be replaced by a longer one.

318is e30: Differential ratio 4,10

318is E36: Differential ratio 3,38 o 3,45

 

- Exhaust

A convenient option is to use stainless exhaust headers since they fit well in the e30 and they improve the performance/power of the engine, mainly at high engine speed. It can be used the stock catalyst of an e36 with the rear muffler of a 325i e30. It is necessary to custom the exhaust to join headers, catalyst and rear muffler and modifications are needed to clear the control arm bushing mount.

 

- Wiring harness

Use this layout as an orientation:

 

E30 C101 conetor 

M50 X20 conector

1 - Alternator - Blue 25 - Azul
2 - Oil level, Static   
3 -   
4 - Coolant temperature sensor – Brown/Violet   12 - Brown/Violet
5 - Oil pressure – Brown/Green 23 - Brown/Green 
6 -   
7 - ECU / DME – Green 21 - Green
8 - Econometer – White/Black or White 24 - White/Black
9 - Enginde speed - Black 20 - Black
10 - Oil level, Dynamic - Blue  
11 - Service interval reset - White/Blue 19 - White/Green
12 -   
13 - Fuel pump - Green/Violet  13 - Green/Violet  
14 - Road speed signal - Black/White 14 - Black/White 
15 - Starter Relay - Black/Green 15 - Black/Green
16 -    
17 -  
18 - Starter – Black/Yellow   18 - Black/Yellow 
19 -  M3 e30 oil temperature  
20-  

 

To make temperature appear in the e30 cluster, the temperature sensor of the coolant of the M50 engine has to be changed by the e30 one.

 

-E30 pre (<85) with rectangular 19 pin C101:

E30 PRE rectangular conector

M50 X20 conector 

1 -  Alternator - Blue 25 - Blue
2 - Oil level, Static   
3 -   
4 - 4 - Coolant temperature sensor – Brown/Violet     12 - Brown/Violet 
5 -   
6 -    
7 - 13 - Fuel pump - Violet/Red 13 - Green/Violet 
8 - Starter – Black/Yellow   18 - Black/Yellow  
9 -   
10 - ECU / DME – Green 21 - Green
11 -   
12 -   
13 -   
14 -   
15 - Oil level, Dynamic   
16 - Oil pressure – Brown/Green, Black/Brown 23 - Brown/Green
17 - Service interval reset - White/Blue 19 - White/Green
18 -  
19 -   

 

In turn, the e30 pre have the C104 connector, located in the globe box area where it is set the ECU, for witch it shall be taken into account the following cables:

C104 conector

M50 X20 conector 

1 - Enginde speed - Black 20 - Black
3 - Econometer – Yellow/White 24 - White/Black 

 

 

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