E30 Zone

My biggest worry/question is - what to do with engine ?! The more I speak with bmw fans, the more confused I get. They split in two groups:

1. One side saying if I fit S50B32 or even B30, then my shell will last just few months and whole geometry will be gone as e30 is not designed to handle such torque and power, its simply not strong enough, cups will separate themselves from shell Also I would need super expensive staged clutch, fitting some expensive thin plates in rear diff which cost around 500. I would need roll cage to stop body moving around. S50B32 will cost fortune to maintain and repair, expensive dual vanos problems. Etc etc. Basically - don`t go there and don`t do this unless you are building track car(which I`m not).

2. Other side is saying - go for it, E30 M3 Evo had 235bhp(and shell is identical even to 316) and just 86 bhp more won`t be any different, shells are engineered with reserve anyway. Just get the front, rear, bottom strut braces . Even a standard clutch would be able to handle this power. Drive shafts would have to be upgraded to much thicker ones from E36 323 Compact or Z3 M Gearbox would have to be changed to bigger and more robust ZF 5 speed as 6 speed boxes from E36 M3 Evo are too weak. Brakes would have to be uprated to bigger ones. Diff would have to be big one.

Guys, please advise what to do?

Do it!
I did and never had any problems. Road going 325i Sport with no special parts needed. I used the E36 M3 5spd gearbox with the standard clutch - perfectly fine for road use and occasional track use. If you use the E36 M3 6spd box you can use an E30 medium case LSD (around 3.64:1 to 3.91:1 ratio) but if you use the E36 M3 5spd box, you will need a longer ratio (2.93:1 to 3.25:1). I used a Z3M 3.15:1 LSD, which is straight fit into the E30.
If you're starting with a 316 you will need to use the bigger 51mm struts and uprate the brakes!
The E30 driveshafts will be fine, no need to upgrade them

The B32 will only cost if its shagged to begin with (the same can be said for the B30). Regular maintenance, oil changes (not forgetting the Vanos filter as many do) will see a good engine last no problem.

I`m looking for 6 speed box and have been offered 3.91 LSD. Is that straight swap with no mods then?

Diff yes. Although I think some people use a 3.64:1 for a more road based car.

6spd gearbox no. You will need a custom crossmember, gear linkage and a custom/modified front prop section.

jmc330i wrote:6spd gearbox no. You will need a custom crossmember, gear linkage and a custom/modified front prop section.

How expensive/complicated is that? I really really would love 6 speed box.

My costom prop which was to weld the e36m3 flange on to the 325 front section, shorten and re balance cost £118 and I now have a fitted 6speed box. I used the IS/m42 gearbox mount and made a custom linkage which was just a case of shortening it and re welding.

I used a firm called Bailey Morris, they do alsorts from big CAT earth movers to tiny props for farm and factory machinery, they even let me walk round the work shop to see what they would do to it.

Ok, so not rocket science. I`ll take 6 speed route then.

Which 6 speed box I need to look for? From same 3.2 Evo m3? Or E46 3L diesel? Is ZF much stronger/better than Getrag? Basically best 6 speed box for E30 with S50B32?

Just another shout for the 3.2. Have had mine fitted in my M3 for 10 years now. Has never let me down, no vanos problems, like above regular oil changes plus vanos filter, check valves clearances, give it a hug now and again because it's just put a stupid grin on your face again? I run the 6 speed with standard clutch, 3.25 diff which even with brisk driving will get nearly 30mpg. With timing gear has clocked 4.9 to 60 and topped out at 158.6 still with road speed limiter fitted. No problems with g/b, change the oil every couple of years, did mod the gear shift to shorten and get the angle just right. Don't know if your cross member is same as M3 but I read lots of crap about needing one made, I turned mine round 180 degrees and it fitted fine with the 6 speed. Again from the vanos point of view, warm it up before reving the nuts of it. Good luck and enjoy.