BMW tech info

BMW cam specs

M50B20NV – intake 240º, 9.7mm lift; exhaust 228º, 8.8mm lift
M50B25NV – intake 240º, 9.7mm lift; exhaust 228º, 8.8mm lift
M50B25TU – in 228º, 9.0mm; exh 228º, 9.0mm
M52B20TU – in 228º, 9.0mm; exh 244º, 9.0mm
M52B25TU – in 228º, 9.0mm; exh 244º, 9.0mm
M52B28TU – in 228º, 9.0mm; exh 244º, 9.0mm
M54B25 – in 228º, 9.0mm, exh 244º, 9.0mm
M54B30 – in 240º, 9.7mm, exh 244º, 9.0mm
S50B30US – in 252º, 10.2mm; exh 244º, 9.7mm
S50B30 – in 260º, 12mm; exh 260º, 12mm
S50B32 – in 256º, 9.7mm; exh 240º, 9.0mm
S52B30 – in 252º, 10.2mm; exh 244º, 9.7mm

M50NV intake cam to VANOS engine exhaust side – remove 2.2mm off the flange from the non-vanos intake cam. The exhaust cam is 62 degrees different from original tool, total by 101 deg.

BMW M50 hot-cam dialing timing:

Intake opens: 19 BTDC (9.5 degrees on the cam)
Intake closes: 41 ABDC (20.5 degrees on the cam)

Duration 19+41+180 = 240 degrees
Lobe Center ((41-19)/2+90)= 101 degrees ATDC

Exhaust opens: 35 BBDC (17.5 degrees on the cam)
Exhaust closes:13 ATDC (6.5 degrees on the cam)

Duration 35+13+180 = 228 degrees
Lobe Center (35-13)/2+90= 101 degrees BTDC

Timing for nonvanos intake cams in exhaust side
Exhaust opens: 41 BBDC (20.5 degrees on the cam)
Exhaust closes: 19 ATDC (9.5 degrees on the cam)

Duration 41+19+180 =240 degrees
Lobe Center (41-19)/2+90= 101 degrees BTDC

Valve diameter

All M series engine valves are 6mm stem diameter
N52, S65 series 5mm stems
N52K, N53, N54, N55 and S55 series 5mm intake, 6mm exhaust

M50B20 vanos and non vanos, M52B20 – intake 29.4, exhaust 26.4, 6mm stem
M52TUB20, M52B22 – intake 29.4, exhaust 26.5, 6mm stem
M50B25 vanos and non vanos, M52B25, M52B28 – intake 32.4, exhaust 29.4, 6mm stem
M52TUB25, M52TUB28, M54B25, M54B30 – intake 32.4, exhaust 30.0, 6mm stem

S50B30, S52B32 – intake 29.4, exhaust 26.4, 6mm stem
S54B30 – intake 34.5, exhaust 30.0, 6mm stem
S65B40 – intake 34.0, exhaust 29.3, 5mm stem
S55B30 – intake 30.4, exhaust 26.6, 5mm intake stem, 6mm exhaust stem

N52K25, N52K30, N53B25, N53B30 – intake 27.7, exhaust 26.6, 5mm intake stem, 6mm exhaust stem
N54B30 – intake 27.7, exhaust 26.6, 5mm intake stem, 6mm exhaust stem
N55B30 – intake 30.4, exhaust 26.6, 5mm intake stem, 6mm exhaust stem
N52B25 – intake 32.2, exhaust 27.0, 5mm stem
N52B30 – intake 34.2, exhaust 29.0, 5mm stem

Part numbers & torque specs

Oil filter housing-to-cylinder block = 22Nm/16lbf ft

Oil filter bracket gasket 11421719855
Oil pan gasket 11131437237, 11139065875
Cam cover gasket 11129070990, 11120030496
Gearbox selector seal (15X21X5) 23121282394, 23121222677, 23128677736

BMW E46 coolant fitting o-rings

16×3 mm – upper radiator hose to expansion tank (1 total)
22×3.5 mm – lower expansion hose, heater hoses (5 in total)
38×4 mm – radiator hoses, lower expansion tank fitting
8×3 mm – temp sensor, lower radiator hose (1 pc)

BMW E36 differentials

E36 320i – type 168, final drive 3.45
E36/5 323ti compact – type 188 differential, final drive 3.07
E36 325i – type 188, final drive 3.15

E36/5 323ti type 188 differential – same as E30 type 188, E34 type 188 (speed sensor plate bigger in diameter, needs to be removed or cut to fit E36/5 rear cover)

Retrofitting E36/5 small case type 168 diff needs smaller diam type 168 halfshafts and prop shaft

M20 single mass flywheel on M50/M52

M20 single mass flywheel is great upgrade to M50/M52 engines if you want to reduce the rotational mass because they use twin-mass flywheels.

Parts and modifications that you will need:

  • M20 flywheel – 228mm clutch disc diameter, single mass. Has the same flywheel/crank bolt pattern, but it has to be machined 4-6mm from the backside to clear the rear crank seal housing.
  • Flywheel bolts – must use shorter M20 flywheel bolts or modify M50/M52 to fit.
  • Starter/ring gear – M20 starter ring gear on the flywheel is different to M50/M52 so there are few options.
    1. Using M20 starter with M20 flywheel (starter doesn’t have threads in the housing so you will have to use bolt and nut to hold it in place).
    2. Replace the starter ring gear on M20 flywheel and fit the M50/M52 starter ring gear. Keep on using M50/M52 starter.
    3. Modify M50/M52 starter to fit M20 ring gear. Replace the bendix to M20 or BOSCH 1006209618/1006209693, OEM 12411722844.
  • Throw out bearing – use E21 323 ’78-82 throw out bearing, 30mm height, part number SKF VKC2151, OEM 21511204525.
  • Clutch – use M20 228 clutch disc and cover.