Need to rebuild S52 - What should I do?

[Iannfld]

Long story short, I've got a knock in the bottom of my S52 in my 89 325is. The head has less than 5000 miles on a fresh rebuild (stock). What should I do? Rebuild bottom end to stock, find used bottom end and put existing rebuilt head on it, find complete used engine, rebuild with upgraded internals?

I'm not sure what way I want to go. I'm leaning towards either rebuilding an upgraded bottom end or just finding a complete used engine. If I were to rebuild the bottom end, what parts should I use? ie what would consist of a sweet build up? I'd probably add cams to the head while I was at it. I'm in denver if anyone has a line on parts or an engine.

Here is a pic of the car, and here are the basics of whats been done to it it:

89 325is
99 S52 bottom end
95 S50 OBD1 head and intake
Euro Maf, 24lb injectors
E36 Transmission
E36 M Brake / 318ti 5 lug swap
Ground control coil overs
95 M3 rack
3.25 LSD
BBR RGR wheels

[Uber E30]

first of all what kind of budget are we talking here?

[Farbin Kaiber]

low mileage m52 bottom end.

[Iannfld]

first of all what kind of budget are we talking here?

I've already got way to much sunk into this beast. I'd like to get away with ~$3K. For $3K (probably less), I could just buy a complete S52, swap all the OBD1 components, and have a spare head sitting around (or for sale). Or could I build a really nice bottom end for this?

[Iannfld]

low mileage m52 bottom end.

Why would I go M52? Did you mean S52? If anything, I'd like to get more power, not less.

[Farbin Kaiber]

Spend 600 on an m52, 200 on a headset... Then a proper DME...


You won't lose that much power, you can actually gain some top end from the swap. Still leaves about 2k for other fun filled mods.

http://www.r3vlimited.com/board/showthread.php?t=120795&highlight=s52+head+m52

Dyno sheet...

http://www.r3vlimited.com/board/showpost.php?p=1219618&postcount=31

[Iannfld]

Spend 600 on an m52, 200 on a headset... Then a proper DME...


You won't lose that much power, you can actually gain some top end from the swap. Still leaves about 2k for other fun filled mods.

What do you mean by proper DME? Aftermarket? I've seen S52 bottom ends for ~1200, so I'd probably still go S52 for only a few more bucks.

Thanks for the input so far...

[Farbin Kaiber]

I mean a chip for the changes in bottom end that will allow for higher redline... There is more wind-up in an m52 than an s52.

[Iannfld]

I mean a chip for the changes in bottom end that will allow for higher redline... There is more wind-up in an m52 than an s52.

Those are some decent numbers with the M52.

That said, I already have the software for the S52 as laid out, so bottom line, I don't think I'll save much by the time I buy new software, and then I'm still down HP from where I am now. I'm at 6500 feet elevation, so I need every bit of HP I can get. Also, saving a few bucks insn't the overall goal...I'm already balls deep on this thing, so since i have to spend some cash, i'd just assume pick up a few HP along the way.

Anyone have suggestions on building a bottom end?

Thanks,

Ian

[Farbin Kaiber]

Well then fuck it, you already answered. Pick up an s52, part your old one and be done with it. least amount of down time, quickest resolution.

[Iannfld]

Well then fuck it, you already answered. Pick up an s52, part your old one and be done with it. least amount of down time, quickest resolution.

I was looking to find out if I should go that route or rebuild the bottom end. Is there any merit to rebuidling the existing bottom end with some upgraded internals? Maybe higher compression pistons, lighther rods or something? I dont' think there are any options for larger displacement are there?

[Farbin Kaiber]

Yes, you could do like MIKe30 did, 11.0:1 CR IIRC.

http://www.r3vlimited.com/board/showthread.php?t=142052

[Devin1205]

rebuilding the motor is very easy to do! rings gaskets and bearing and down the road you go. do you not have the tools for this job? (then buy a new motor) rebuilding the motor can be done in 4-5hrs easy if its already out. i'd help if you were in vegas. how bad is the knock? if its too bad and you wore through the bearings then you might need a machine shop to help you clean the crank and or rod up a bit. if your internals are a little hurt from this you would need a over sized bearing worst case. If you step into modding the motor you are opening up a much bigger project that only you can decide if its worth the extra time and money or just to get it running good as new again. Devin

[Iannfld]

rebuilding the motor is very easy to do! rings gaskets and bearing and down the road you go. do you not have the tools for this job? (then buy a new motor) rebuilding the motor can be done in 4-5hrs easy if its already out. i'd help if you were in vegas. how bad is the knock? if its too bad and you wore through the bearings then you might need a machine shop to help you clean the crank and or rod up a bit. if your internals are a little hurt from this you would need a over sized bearing worst case. If you step into modding the motor you are opening up a much bigger project that only you can decide if its worth the extra time and money or just to get it running good as new again. Devin

The knock isn't very bad. It goes away when the engine is up to temp (a couple of minutes) and sounds fine after that. Who sells rebuild kits for these? I've got basic tools, nothing fancy. What special tools do I need? There are some needed for the head install correct? Any idea where I can get them?

This sounds like it might be a good solution. I'd probably prefer a rebuild as I got this bottom end used, and didn't get much life out of it. Atleast if I rebuild it, I know what I have. I assumed I would have to get the block and crank machined, but sounds like I could get away without?

[madjurgen]

The knock isn't very bad. It goes away when the engine is up to temp (a couple of minutes) and sounds fine after that.

Uh, I'd confirm you spun a bearing first. Rod knock doesnt go away with temp.