I can not decide! M52 or S50

[rickysbmw320i]

Im looking for the most cost effective way to put a 24v in. My biggest concern with the m52 is the OBD1 swap. Is it as hard as it seems? Also, What is a decent price for a decent s50? I am not looking for something that is bat shit fast ( i already have that in my e21) but am looking for something with a bit of power, yet dependable. This is my DD and it is almost time to dump the m20. I mean it is still strong but i think alot of little things like the belt, channel beween oil and coolant in the head gasket, ect. I prolly still have a good 50k left but i just want to get the 24v in before anything happens. So if i could get your input, that would be great?

Forgot to mention, Im not incredibly familiar with the m52/or m50. I know everything there is to know about the m20 and m10. so, if you have any pointers, that would be appreciated as well.

thanks,

-Rick

[FredK]

Well, if you've tinkered a lot with M20s and cars in general, an OBD-I swap is really easy. It all becomes logical when you have all of the parts in front of you. It's mostly a wiring swap. If you take the time to lay everything out, tag all the wires, and read over a few OBD-I swap writeups, it should be easy.

A decent S50US runs around $2500 to 3000+ depending on mileage and completeness.

[mongule]

You can always keep the OBD2 and save quite a few hundred bucks.

[matt]

I would do an OBDI M52 in a heartbeat if I were doing it again.

We've built a few recently that have put out excellent numbers.

[Jean]

I am in the middle of converting my 98 m52 to obd1, it's not too hard, I think the biggest issue will be trying to be wiring or specifically figuring out what connector on the obd1 harness goes where.
It really hasn't been that difficult so far, I just got my 413 ecu and obd1 vanos harness the other day maybe this weekend will start figuring out what goes where. I went with obd1 manifold/tb, fuel rail, valve cover/coil packs, obd1 vanos solenoid/knock sensors. I still need to order two more sensors and the correct oil pick up and dip stick/tube, oil pressure sensor, obd1 manifold brackets ...

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1898&hg=11&fg=10

oil dipstick tube - 11431738169
dipstick tube gasket - 11431287541
dipstick - 11431720875
dipstick tube bracket - 11431735535 up to 7/91?
oil pan gasket - 11131437237
oil level gasket - 12611277129

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1277&hg=11&fg=30

oil pickup 11411748150 25.99
oil pickup gasket 11411703947
oil pump 11411740155 300?

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_0157&hg=11&fg=10

cam sensor - 12141726066 86.22
pulse generator on front

pulse generator on side of the head

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1282&hg=11&fg=15

or 12141740959 from 9/92 91.88

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1161&hg=11&fg=10

2 knock sensors - 12141738667 78.66

oil assembly stuff from 9/92

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1288&hg=11&fg=30

gasket 11421719855
oil pressure switch 12611710509
ring gaskets 32411093596

obd1 manifold parts

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1124&hg=11&fg=40

tb to manifold gasket - 11611716174
front bracket - 11611735265
rear bracket - 11611735427
hose clamp - 11611738165
connector - 11611738629
connector o ring - 11611730725
connector - 11611735800
connector o ring - 11611735859
manifold hex nuts - 07129902630 how many?
temp sensor o ring - 11611735736
temp sensor gasket - 11611735735


valve cover gasket (m50/s50 style?)

[hugh jass]

do you have a e36 bentley jean? that has the wiring color for the different sensors. all you have to do is peel back the rubber around the plugs on the harness and match up the wire colors with the wiring diagram. takes about a half hour. you can use my bentley if you don't have one.

[FredK]

manifold hex nuts - 07129902630 how many?

7

[rickysbmw320i]

I am in the middle of converting my 98 m52 to obd1, it's not too hard, I think the biggest issue will be trying to be wiring or specifically figuring out what connector on the obd1 harness goes where.
It really hasn't been that difficult so far, I just got my 413 ecu and obd1 vanos harness the other day maybe this weekend will start figuring out what goes where. I went with obd1 manifold/tb, fuel rail, valve cover/coil packs, obd1 vanos solenoid/knock sensors. I still need to order two more sensors and the correct oil pick up and dip stick/tube, oil pressure sensor, obd1 manifold brackets ...

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1898&hg=11&fg=10

oil dipstick tube - 11431738169
dipstick tube gasket - 11431287541
dipstick - 11431720875
dipstick tube bracket - 11431735535 up to 7/91?
oil pan gasket - 11131437237
oil level gasket - 12611277129

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1277&hg=11&fg=30

oil pickup 11411748150 25.99
oil pickup gasket 11411703947
oil pump 11411740155 300?

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_0157&hg=11&fg=10

cam sensor - 12141726066 86.22
pulse generator on front

pulse generator on side of the head

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1282&hg=11&fg=15

or 12141740959 from 9/92 91.88

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1161&hg=11&fg=10

2 knock sensors - 12141738667 78.66

oil assembly stuff from 9/92

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1288&hg=11&fg=30

gasket 11421719855
oil pressure switch 12611710509
ring gaskets 32411093596

obd1 manifold parts

http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1124&hg=11&fg=40

tb to manifold gasket - 11611716174
front bracket - 11611735265
rear bracket - 11611735427
hose clamp - 11611738165
connector - 11611738629
connector o ring - 11611730725
connector - 11611735800
connector o ring - 11611735859
manifold hex nuts - 07129902630 how many?
temp sensor o ring - 11611735736
temp sensor gasket - 11611735735

valve cover gasket (m50/s50 style?)

Thanks for the info! this is all you need for the swap to OBD1?

[rickysbmw320i]

I would do an OBDI M52 in a heartbeat if I were doing it again.

We've built a few recently that have put out excellent numbers.

May i ask what kind of numbers? also, if you have the m50 and still would do the m52 in a heartbeat, then that tells me something.

[Jean]

do you have a e36 bentley jean? that has the wiring color for the different sensors. all you have to do is peel back the rubber around the plugs on the harness and match up the wire colors with the wiring diagram. takes about a half hour. you can use my bentley if you don't have one.

I've been looking at the e36 schematics but my harness is from a 93 525i auto so I might need to get an e34 bentley?

I see that knock sensors also need to be mounted in right order (1-3 vs 4-6) according to the manual, but both sensors use same wire colors (black and brn/org on both?).

o2 sensor, fuel injection valves and ignition coil wiring is clear. If I read the schematics correctly then idle speed control is (wht/grn, wht/yel, red/wht); evaporative emission valve? (grn/blue, red/wht); crankshaft position rpm sensor is blk/yel; intake air temp sensor gry/brn; tps is red/yel, brn/blk, brn; engine coolant temp sensor is brn brn/red; camshaft (hall) sensor is yel, red/wht, brn/org; hot film mass sensor is blk, gry/yel, red/wht, brn/org.

I don't know if the data link connector for obd diagnostics?
And if I need to remove 11 transmission control module (EGS) wires?

7

thanks :)

[FredK]

I see that knock sensors also need to be mounted in right order (1-3 vs 4-6) according to the manual, but both sensors use same wire colors (black and brn/org on both?).

Using a multimeter or test light, trace the knock sensor connectors on the harness back to the DME connector, shown below.

Pin 69 is the Cylinder 4-6 knock sensor
Pin 70 is the Cylinder 1-3 knock sensor
Pin 71 is the ground for both knock sensors

[Jean]

Makes sense, I was thinking that's what I would have to do. I gotta find an e34 bentley and compare if the wiring is different just in case.

[SpecM]

I would do an OBDI M52 in a heartbeat if I were doing it again.

We've built a few recently that have put out excellent numbers.

what's the reason that m52s put down more power than m50s?

or did I misunderstand you?

[matt]

M52s absolutely do put down more power than M50s. It's a better motor in every way. Technology marches forward. S52 cams in an M52 are freaking amazing also.

We've made anywhere from 210whp NA with M3 cams and basically nothing else all the way up to 550whp with a Stage 2 turbo and a thick headgasket, still running pump gas.

NA... We can do 200-270whp from a 2.8... just depends on how much you want to pay.

[Jean]

Matt,

if I win a lotto I'll be sure to send my m52 yourway to build/tune it to 240whp NA.

Jean