M50 mootorivahetus

First I would like to give a word of advise to anyone

doing this swap. If your main goal is making your E30

fast, do not do a 2.5L swap.

Trust me you will be disappointed. In my opinion the

smallest engine you should put in your E30 is a 2.8L

M52. The simplest and probably most economical engine to

swap is a 3.0L S50 engine out of a 95 M3 primarily

because it already comes with most of the OBD I hardware

you will need for the swap.

The only problem with 95 S50 motors is that they are

becoming old and it is very hard to find one in good low

mileage condition for a reasonable price. You might want

to consider an option of building a high compression

2.8L engine that will perform on par with a 3.0L and

cost less. One good way of building a low budget high

performance 2.8L is purchasing a 2.5L M50 engine out of

a 525I (so you can get your oil pan) and stroking it.

There are plenty of 2.8L core engines out there for as

little as $200. One trick of making it high compression

is reusing the 2.5L pistons (only if in great condition

with new rings) with 2.8L rods and 2.8L crank. The

combination will give you a compression ratio of around

11.25:1 according to my estimates. With M3 cams (ether

3.0L or 3.2L) the engine dynos at around 240-250

crankshaft horsepower with stock injectors. Upgrading

injectors would probably make even more power because

the engine leans out and stops making power after 6200

rpm. One downside to this high compression is you have

to use the best gas money can buy. Sometimes in hot

weather the engine will ping even on a 91 gas so if 92

or higher octane gas is not available in your state you

probably shouldn’t consider this option.

Things that need to be modified:

Brake Booster: Use an E21 320I brake booster. Some

people use 325IX brake boosters but 320I boosters are

cheaper and allow you to use your stock master cylinder.

Note how the fins are ground down to clear the brake

booster.To make the 320I brake booster work in your E30

you will need to cut the shaft off to the same length as

your E30 booster, grind it down to the same thickness

and thread it with a 10X1.5mm dye.

Be careful here, if you screw it up you will need to go

out and get another booster, the shafts are non

replaceable. Don’t forget to grind off some of the fins

on the back of the intake manifold to clear the brake

booster.

Transmission: There is a bunch of different

transmissions you can use in this swap. Some people keep

their E30 Getrag 260s but it requires fabricating a

custom transmission mount and your shifter will be

offset to the right by about 15-degrees. My favorite

transmission to use is S5D320Z out of a 95M3, 96-00 328

E36 E46, 96-99 M3. The reason I like them best is

probably the fact that you c+9+an use a 135mm guibo on

them and they are rated for 320hp, which should give you

plenty of room if you are planning future modifications.

S5D320Z transmissions are not the lightest but they are

the strongest. You can use your stock 325 or 91 318I IS

transmission mount with any E36 transmission. Don’t

forget to use E21 320I transmission mounts (they are

stronger then e30 or E36 mounts) and weld two cups to

the transmission mount to prevent the engine and tranny

from moving around too much and hitting the radiator

(see pic).

Transmission Mount Reinforcement. The shifter arm has to

be out of an E36 328 or M3 along with the aluminum arm

that connects to the top of the tranny.

Drive shaft: If you are using a ZF S5D320Z transmission

you will have to use a drive shaft out of an E30 M3, 98

M3 (U-joint type only), 87-88 325E or 96-98 E36 328. Use

the E30 center support mounted backwards on E36 drive

shafts.

Clutch: The ultimate clutch is of course E36 M3 but some

people on the budget use an E36 328 clutch (it is the

same diameter as M3 clutch). Those who use a 328 clutch

can also use a flywheel out of an E46 323I or a 2.8L Z3.

It is virtually identical to a 328 flywheel but lighter.

Firewall: Cut some of the insulation off the heater

blower motor cover. Some people strip it completely but

I take a long knife, put it parallel to the firewall and

remove some material.

Do not get rid of the rubber drain on the passenger side

of the firewall that drains the water from the wiper

motor compartment or you will end up with water in your

spark plug holes every time you wash the car. Bend the

heater pipes towards the driver’s side of the car and

down about an inch to clear the intake manifold.

Engine mounting: The engine can be installed completely

assembled with all accessories except the front harmonic

balancer, A/C bracket or A/C compressor.

I prefer to install the engines completely stripped

since it makes it easier to connect the heater hoses .

For the aluminum mounts you have to use the E36 arms.

The rubber mounts are out of an E24 E28 (part number 11

81 1 132 793). The mounts have to be mounted in the

outside mounding holes of the sub frame.

Note the aluminum spacer under the engine mount.It is a

good idea to reinforce the sub frame if you are using a

3.2L motor. Some times the engine mounting points rip

out from a lot of torque.

Cooling System: The radiator has to be out of an 88+ 325

E30. Some people use E36 radiators but if you plan on

using a mechanical fan E30 radiator will give you more

clearance. Speaking of clearance it is very important to

reinforce the transmission mounts or the first time you

slam on your brakes the fan will end up destroying your

radiator. The fan clutch has to be stock E30 with a

9-blade fan. Do not use an 11-blade fan because it will

give you less radiator to fan clearance. The overflow

tank has to be out of an 88+ E30 as well. Don’t forget

to upgrade the thermostat housing and the water pump to

the metal kinds on your M50 motor. The bottom radiator

hose off the M50 motor will need to be cut down to fit

in E30. The top hose you can get from any auto part

store.

Note how little clearance there is between the fan and

the radiator, only about 7mm.Just look for a long

radiator hose with a 90-degree bend. The heater hoses

connect the same way they were on your E30 (the long

hose under the intake manifold goes to the top inlet and

the short hose that connects to the cylinder head goes

to the bottom inlet), do not eliminate the bypass valves

(recall items).

Lubrication System: The oil pan has to be out of an M50

powered E34 525I. You will also need to get the pickup

tube with a gasket and the oil dipstick. E36 dipstick

can be modified to fit but it will not show you the oil

level correctly. Do not forget to safety wire the oil

pump or at least locktight the sprocket nut. Drill a

hole through the oil pump shaft and the bolt, insert a

stainless steel wire through the hole and tie it up. M50

engines are known for the oil pump sprocket bots to come

loose.

Oil coolers are also a good idea for the track. Oil

temps get to about 240+ degrees if you drive your car

hard enough.

A/C: Just about every town has a shop that will

fabricate customs A/C hoses. When you get your engine

from a junkyard try to get the A/C hoses with it. Custom

hose shops will be able to connect the E36 A/C hose

connectors to your existing E30 hoses. You can also get

some fittings from your local hardware store and clamp

the hoses together yourself. Don’t forget to flash out

your system to get rid of all R12 oil. Use PAG oil only

with your E36 compressor or it will not last you very

long.

Differential: The best ratio for 3.0L or 3.2L cars is

3.25 and the best ratio for a 2.8L or a 2.5L is 3.46.

3.25 differentials can be found in E28 525e 535I E24

635. 3.46s can be found in same cars but are more rare.

The output shafts and the rear cover have to be swapped

to make the differentials work in E30. You can also get

a rear cover out of an M Coupe. The M Coupe covers lower

the differential oil temperatures and look very cool

behind your E30.

Exhaust: Exhaust is truly something that should be left

to a professional unless you are an experienced welder.

You can use the stock E36 cats out of a 92-95 325 or M3

but the right side pipe will need to be modified to

clear the control arm bushing mount.

As you can see the right side exhaust pipe is still very

close to the control arm bushing bracket. In this case

there is only about 5mm of clearance.

The O2 sensor mounting port interferes with the frame

reinforcement behind the transmission mount. You can cut

a chunk out of the brace to make the O2 sensor fit and

reinforce the brace by welding it to the transmission

mount with a couple of pipes.

96+ exhaust pipes are larger in diameter then 92-95 and

pose some clearance issues. 96+ exhaust pipes are bigger

in diameter on the outside but they are double walled so

in reality they don’t flow more then 92-95. OEM pipes

are stainless steel and a very hard to weld unless you

are equipped to weld stainless steel. Stock cast iron

headers from 92-95 can be used.

You will need to make some 5 mm spacers for the engine

mounts to raise the engine so the pipes clear the sub

frame. It is also a good idea to remove the studs out of

the headers and use the bolts to mount your exhaust,

makes it way easier to get the pipes in there. The left

exhaust pipe will need to be flattened out to clear the

sway bar.

You can also use stainless steel headers from 96+ E36;

they look way better then the rusty cast iron headers.

To use the 96+ headers buy two O2 sensor plugs from your

BMW Dealer (originally install on a 98 323IS) and weld

up the air injection ports. The muffler is up to you but

the pipes to it will have to be custom made.

Steering: When you get your engine try to get the power

steering pump and hoses with it. It is a good idea to

replace your rack when you are swapping the engine. The

rack in an M50 powered car is almost impossible to

replace without considerably lifting up an engine or

dropping the sub frame, the oil pan sits very close to

the steering rack.

Suspension: Nothing needs to be done to suspension

unless you want to improve the handling of your E30. M50

engine is slightly heavier then M20 (around 60lbs

heavier). Although 60lbs doesn’t sound like much you

will be able to feel it. Thicker sway bars do wonders on

M50 E30s.

Wiring and Electrical: The best wiring harness to use is

out of a manual 93-94 325I due to its simplicity,

although it is not that hard to modify a wiring harness

from an automatic car or a car with traction control and

EWS. The process is as simple as laying the harness out

on a table with a diagram in front of you and

eliminating anything that is not necessary. If you ended

up with a harness out of an automatic car simply cut all

of the wires out of the engine harness that belong to

the automatic transmission computer. Automatic

transmission computer is wired directly to the engine

computer harness; the only wire that needs to be

modified is a “brown/black wire pin 26 transmission ECU”

need to be connected to any “red/white wire on the main

relay”. ECU has to be out of a 93-94 325I with the Bosch

part number ending in 413. You can use an ECU out of a

95 325I or a 95 M3 but you will need a special chip that

eliminates EWS. To make the E36 harness plug in to your

E30 you will need to make an adapter. To make an adapter

you will need to get a wiring harness connector off the

E36 (body side) and an engine harness connector off an

E30 (engine side). See the excel spreadsheet for pin

assignments. The coolant temp sensor for the ECU has to

be out of an E36 and the coolant sensor for the temp

gage has to be out of E30 (single pin sensor brown).

Alternator has to be out of any 6-cyl E36, I prefer to

use 80AMP alternators but if you have a powerful stereo

you might consider using a 140AMP alternator (it will

suck up more engine power though). Starter has to be out

of any E36, Z3, E46 323 328, E34 E39 or E30 318is. Don’t

forget to the engine ground strap, with M50 engine it

mounts on the passenger side of the car.