M50 TU Stroker

Post Wed Jan 16, 2013 8:59 am

I know of the 2.8 Stroker conversion that can be done to a M20/2.5

But is it possible to fit the M52/ 2.8 Bottom end internals to the M50TU/2.5 24V engine?.

My 323i engine has just given up and i was thinking of going the M50TU 2.5 route as i have heard that if the M52/2.8 fails its not worth trying to rebuild and you're better off getting another to replace it with, have also been told that there are issues concerning the M52 lump.

Also, how much difference is there power wise between the M52 and M50 lumps.

I want to run the M50 on an M42 Box and 3.9 LSD, is this a suitable set up?

Post Wed Jan 16, 2013 9:19 am

Welcome to the zone!

Basically,M52 is an M50 but cast in aluminium,bore is the same,bore spacing the same.The snag with the ali block is that the steel head bolts are not really long enough,so if the engine is over-heated and pops it's head gasket,re-torquing the head tends to pull the threads out of the block.

A number of zoner's have now built hybred M52's,using the internals of an M52 in the cast iron M50 block.The standard power output of 2.5 M50 and 2.8 M52 is almost the same at about 190bhp,but the longer stroke engine produces significantly more torque.Bolting on the M50 inlet manifold raises output to around 220bhp,with suitable mods to the ECU.

M42 gearbox is the Getrang 240,first seen in the late '70's behind the E21's 323i engine,this gave about 150bhp,'box should be good for a 50% increase in engine output,so you are getting close to it's limits....however,I have used the same 'box with my M50 for several years with no problems.But my engine is standard spec,of course!
Alternate 'box would be the ZF used with M50/52 in E34/36,but this has a direct drive 5th gear,as apposed to the overdrive 5th of the Getrang,so you would need a diff somewhere around 3:1/3:15,E30 M3 or certain E28 diffs can be modified to fit.

Hope this helps....

Post Wed Jan 16, 2013 1:33 pm

Ive done this build, info in my thread here - http://www.e30zone.net/modules.php?name ... me&start=0

Page 3 for engine specs

Post Wed Jan 16, 2013 1:36 pm

Lot of farting around for 190bhp.... you 24v boys need your heads feeling.!

Post Wed Jan 16, 2013 1:56 pm

daimlerman wrote: Getrang

Getrag - it's for GETRieb AG or loosely translated 'Gearbox Company'.

The 240 arrived in 1982 for the E30. Before that was the 242, 245 etc.
There are two M42 boxes, the E30 and the E36. The E30 is an overdrive box, the E36 one (Gertrag 250) is not.
The 240 and 250 boxes are alright but were not designed to handle the torque of a 2.8. They will do it, but for how long, nobody knows.
The 260 gearbox from the E30 325i is much, much better. A 3.9 diff is too low really and will be quick but very revvy. A 3.7 or 3.64 is better. If you use an E36 close ratio box (328i is best) you can run a diff in the 2.93-3.25 range. A 3.25 E30 M3 diff would be absolutely perfect.

You can transfer the 2.8 crank, rods and pistons into an M50 iron block. But, you must make sure the M52 2.8 donor engine is a steel liner one. The pistons in the Nikasil bore units are not really suitable.

Ultimately, it's something of a waste of time. These days you can buy any number of sweet running 2.8 M52 engines for £250. The alloy block isn't as forgiving of overheats as the iron block, but it's a shitload lighter and there is a never ending supply of MOT failed manual E36 328i and E39 528i cars around for buttons. On both, you buy one for £400, remove the engine, sell a few spares and weigh the rest in for scrap......and you have an engine owing you about 80 quid.

Post Wed Jan 16, 2013 2:03 pm

The weight difference between stripped down iron and alloy block is 20kg

Ive always found the 3.25 diff with E36 box to be geared about the same as using a 3.91 diff with an overdrive box, very revy
3.07 or 3.08 are both perfect IMO, 3.15 and 2.93 close also

Post Wed Jan 16, 2013 2:09 pm

mcbonio wrote:Lot of farting around for 190bhp.... you 24v boys need your heads feeling.!

Perhaps you could enlighten us as to how to achieve more for less spend.

Post Wed Jan 16, 2013 4:19 pm

Thank you guys for all the replies and for the welcome.
I was also told that a 318is box running with a 3.9 lsd diff is the way to go???

I want it to be quick off the mark but not horrible on the Motorway by revving too high.

Please advise of the best and more importantly most reliable set up.

Thanks

Post Wed Jan 16, 2013 4:24 pm

DanThe wrote:
Ive always found the 3.25 diff with E36 box to be geared about the same as using a 3.91 diff with an overdrive box, very revy
3.07 or 3.08 are both perfect IMO, 3.15 and 2.93 close also

Post Fri Jan 18, 2013 8:34 pm

daimlerman wrote:
mcbonio wrote:Lot of farting around for 190bhp.... you 24v boys need your heads feeling.!
Perhaps you could enlighten us as to how to achieve more for less spend.

^ This, Lets face it it's not really THAT much work compared to other methods of getting similar power.

How did the m52 pistons work out in an iron block dan?
What hone did you have them do and what clearances did you run?