M50B25 or M52B28?

[Andyboy]

Yep. Assuming you can find a guaranteed good 2.8! It's still £500-1000 worth of engine and if you're doing a conversion from scratch involving an engine rebuild, a 12v 2.8 M20 would be easier. A good one would do 210 bhp but the cost of a cam to get past 200 might be prohibitive.

If it's of any interest I know of a non vanos alloy block 2.8 for sale. It uses a really good unworn Nikasil block, brand new pistons, polished crank, bearings, rod bolts etc plus a rebuilt non Vanos 325i head. It's done about 4000 miles and it goes like a rocket. I'll find out how much it is if anyone is seriously interested.

[jmc330i]

So which would be the best head to use on an M50 block with the M52 crank?

Does using the M52 crank in the M50 block (I guess with M50 rods, pistons) make the M50 into a 2.8ltr?

[m-dtech]

Yep. Assuming you can find a guaranteed good 2.8! It's still £500-1000 worth of engine and if you're doing a conversion from scratch involving an engine rebuild, a 12v 2.8 M20 would be easier. A good one would do 210 bhp but the cost of a cam to get past 200 might be prohibitive.

If it's of any interest I know of a non vanos alloy block 2.8 for sale. It uses a really good unworn Nikasil block, brand new pistons, polished crank, bearings, rod bolts etc plus a rebuilt non Vanos 325i head. It's done about 4000 miles and it goes like a rocket. I'll find out how much it is if anyone is seriously interested.

i think the point in previous posts is to get away from the m52 nikasil blocks and use the normal m50 block with the m52 crank.

[Jimbob]

Andy, let me know about that 2.8 please fella!

[DanThe]

Does using the M52 crank in the M50 block (I guess with M50 rods, pistons) make the M50 into a 2.8ltr?

You need the 2.8 rods and pistons, I read that the 2.5 pistons can be used and will give something like 11.3:1 compression which would be way to much for my liking. That sort of compression needs race fuel!

[Brianmoooore]

That sort of compression needs race fuel!

Or LPG

[DanThe]

Or LPG

This is getting better by the minute

[320Touring]

Arrgh! more 24v wrongness

although a 2.8 on LPG puttin out some serious ponies sounds like a plan

[Jamesb318is]

Only when you use the wrong head bolts - i.e the ones for the iron blocks. Unless the engine has been seriously cooked the correct head bolts should torque up okay. The problem comes from the non BMW 'universal' head bolts which are slightly shorter. The threads only engage in 2/3 of the threads on the alloy block, overload the threads and rip them out.

Interesting, we only use approved BMW bolts though, being a main dealer.
Seen it happen a good few times and the engines are not usually cooked.


This M50/M52 hybrid sounds brilliant! What a combo! I may be able to get my hands on a complete shagged m52 2.8, so i can steal the good bits!

[m-dtech]

i like the sound of it too............ suppose i can always upgrade my crank, rods and pistons at a later date....

[DanThe]

Well I stripped the M52 block out this evening,

Big ends are bearly run in



Mains also look good, this is the worst





Will consider getting em polished and new shells depending on price, anyone got a rough idea of polishing and new shell costs?

This \/ is a pig



Worst part of the job

[jmc330i]

Does using the M52 crank in the M50 block (I guess with M50 rods, pistons) make the M50 into a 2.8ltr?

You need the 2.8 rods and pistons, I read that the 2.5 pistons can be used and will give something like 11.3:1 compression which would be way to much for my liking. That sort of compression needs race fuel!

So M50 block and head with M52 crank, rods and pistons would be a good way to go? Or atleast, the way to make a 2.8 with decent power and no block issues (nikasil).

[Jimbob]

Yes!
However, I'm prepared to take this risk of a 2.8 block

[jmc330i]

TBH, if I got offered a good M52 then so would I.

But I can most likely get a good M50 easily enough and then find an M52 as and when to rob the bits from.
I was actually offered a 94 525i touring on my way home from work yesterday, but turned it down

[Jimbob]

There's a cheap one on ebay here, but after reading that vanos consumes power I'm off the idea.
The engine Andy mentions sounds spot on for me

[Turbo-Brown]

Will consider getting em polished and new shells depending on price, anyone got a rough idea of polishing and new shell costs?

Can't imagine a polish being more than £30 or £40 or so (can't remember how much mine was now) but the big ends were about £40 and the mains £60 or something.

[DanThe]

Not expensive then, is that dealer prices on the bearing shells?

[dlatch]

im gonna stick with my 2.5 non vanos and turbo lol, i have been saying this for aaaaaages.

should be on the road late january.

that sounds like the plan to me too stick some boost up the M50 will be interesting to see how it compares to the earlier engines boosted

[Jimbob]

Is the original E30 cooling system OK to use or do people use parts from the E36/E34 donor?

[Brianmoooore]

Original M20B25 rad in my M50 with no problems, but there are loads of options.

[DanThe]

You can use the E36/E34 rad but I didnt due to the tank on the side being too close to my airbox. Ive got the same system as Brian but it does get a bit too hot for my liking, maybe the aftermarket rad isnt as good, I will get round to fitting an air-con rad sometime though which should improve the system.

The best rad for the job IMO is the E36 M3, it fills the space available height and width wise but I cant use it due to where my airbox is, you can run it with the M20 expansion tank.

[Andyboy]

Only when you use the wrong head bolts - i.e the ones for the iron blocks. Unless the engine has been seriously cooked the correct head bolts should torque up okay. The problem comes from the non BMW 'universal' head bolts which are slightly shorter. The threads only engage in 2/3 of the threads on the alloy block, overload the threads and rip them out.

Interesting, we only use approved BMW bolts though, being a main dealer.
Seen it happen a good few times and the engines are not usually cooked.

And the reason you are taking the heads off is because............the head gasket's gone and it's overheated!
If the threads were stripping on good uncooked blocks, they would be so seriously weak as to suggest a major design flaw and they'd also be pulling threads out on the assembly line.
Main dealer work doesn't guarantee anything. The worst I ever saw was a 528i that had a block swap where they managed, somehow, to fit a 2 litre short engine. The engine ran for a couple of seconds until all the valves were bent.
On another 728i the nikasil engine was removed and a new 2.8 short unit fitted along with new valves. It ran for a few thousand miles until the head gasket went. The head gasket was replaced but it went again a year later, out of warranty, tough shit.
The head was removed again where it was found that the wrong (M50) bolts were fitted and the block had been helicoiled. the helicoils had all pulled out, and the engine was scrap.

Niiiiiiiiiiiiiice!!

[Turbo-Brown]

Not expensive then, is that dealer prices on the bearing shells?

That was from my friendly local machine shop.

Just found the receipt actually:

1 Set main bearings: £63.18
1 Set Big end bearings: £46.69
Polish Crankshaft: £20

[Jimbob]

OK thanks guys, sounds like either way will work quite easily then.

So for anyone viewing this thread this list might be of some use:

: An M50/2 engine (look for non-vanos engines with non-ews wiring loom(E34))

: Inlet manifold, throttle body and throttle cable from E34

: Modification to exhaust manifold - In the words of Brianmoooore: For the exhaust manifolds, I used a standard cast E36 rear manifold and a cast E36 front manifold with the section between where the three primaries meet and the flange removed and welded together.
Then, by chopping up the front pipes of an E36 system and a 325 E30 system and welding the bits together, I connected to the standard 325 E30 system just in front of the gearbox exhaust mount.

: Sump, oil pick up pipe and dipstick from E34 (Is it the same oil pump for E36 and E34?)

: E36 ally engine mount legs

: E34 M50 rubber engine mounts (or so I'm led to believe)

: E30 325i clutch and flywheel (6-7mm off of flywheel)

: E30 325i gearbox (custom gearbox mount/bracket, bend the selector rod 10-15 degrees!)
http://i11.photobucket.com/albums/a155/ ... G32336.jpg

: The above allows for an E30 325i propshaft, and a 3.64 diff at least (pref M3 diff)

: Mk2 golf brake servo with spacer between pushrod and master cylinder

: E30 325i everything else

All of the above has been taken from many searches and delving deep into this section of the forum, some great input from people such as DanThe, Brianmooore and many more.
I think that's it! Sorry, just get fed up with a new thread every other day "328i into 320i" etc!

[DanThe]

Only thing I dissagree with is the preferred E34 loom, simple to install yes, but the E36 loom allows the ECU to be placed just inside the cabin, with the E34 loom you have no choise but to either mount the ECU on the battery tray or lengthen the 40 odd wires.

E34 loom = simple to install but short ECU branch
E36 loom = slight modding needed on power cables but longer ECU branch

[Jimbob]

Down to opinion I guess mate!

Have a good one.
Cheers
Jim

[Jamesb318is]

Only when you use the wrong head bolts - i.e the ones for the iron blocks. Unless the engine has been seriously cooked the correct head bolts should torque up okay. The problem comes from the non BMW 'universal' head bolts which are slightly shorter. The threads only engage in 2/3 of the threads on the alloy block, overload the threads and rip them out.

Interesting, we only use approved BMW bolts though, being a main dealer.
Seen it happen a good few times and the engines are not usually cooked.

Sorry, just realised that that came across like i was trying to say i knew better, and i was being sarcastic, i wasnt and i stand corrected.

Despite working for a main dealer I am no way under the the impression that that makes our work superior, (ive seen and heard a few horror stories too!) although i like to think i really care about what i do, take my time and do a good job!

[m-dtech]

Only thing I dissagree with is the preferred E34 loom, simple to install yes, but the E36 loom allows the ECU to be placed just inside the cabin, with the E34 loom you have no choise but to either mount the ECU on the battery tray or lengthen the 40 odd wires.

E34 loom = simple to install but short ECU branch
E36 loom = slight modding needed on power cables but longer ECU branch

or megasquirt it to get the full 200 horses outta the lump

[DanThe]

You dont need to go to the expense or effort of mega squirt to get 200 hp

[g57yle]

ok, due to probems in the past with the alloy blocks i did my very own conversion, basically use the internals of the M52 B28 e.g. Crank, pistons and rods and put them in a cast iron M50 block, with the same bore diameter. Then use either 2.5 or or 2.8 head whick im pritty sure are the same although i havent compared the valves or cams. but both cylinder heads have 2.5 stamped on them for some reason or another, and ive seen this on all the m52 b28's. Then you have a nice starting point.

one thing is if your using the standard 328i manifolds the lambda sensor wedges against the water drain plug hole on the block, but ive done this on my cuses 328i with the alloy problem and its been great ever since

[alexbaby88]

ok, due to probems in the past with the alloy blocks i did my very own conversion, basically use the internals of the M52 B28 e.g. Crank, pistons and rods and put them in a cast iron M50 block, with the same bore diameter. Then use either 2.5 or or 2.8 head whick im pritty sure are the same although i havent compared the valves or cams. but both cylinder heads have 2.5 stamped on them for some reason or another, and ive seen this on all the m52 b28's. Then you have a nice starting point.

one thing is if your using the standard 328i manifolds the lambda sensor wedges against the water drain plug hole on the block, but ive done this on my cuses 328i with the alloy problem and its been great ever since

Have you done a dyno of your M50B28 hybrid? Did you have to rechip the ECU?

[gorgeee]

with using the crank from the m52 in the 2.5 m50 what other changes need to be made?
does anything need to be done to the timing or is it a case of just getting an uprated chip?

[gorgeee]

with using the crank from the m52 in the 2.5 m50 what other changes need to be made?
does anything need to be done to the timing or is it a case of just getting an uprated chip?