M50 head on M20b25 engine

[mavrikno13764]

stupid question, but i got curious. Does the M50 head fit on the M20b25 engine block? twin cam FTW!

[lachssilberbim]

Might have a problem with timing? haha

[rs4pro3]

The head it self bolts on, but some oil and coolant passages don't line up, and you have to figure out some way to do a sealed timing chain system

[deathray187]

The head it self bolts on, but some oil and coolant passages don't line up, and you have to figure out some way to do a sealed timing chain system


that part is easy: m50 block conversion

[SWISS]

that part is easy: m50 block conversion :rofl

[mavrikno13764]

is the swap common?

[iflytii]

Don't know if any of you guys remember that (edit - see below) RD made a 4 valve head for the m20 motor. Unfortunately they destroyed the castings and recent inquires have concluded they have no interest in reproducing it as it would cost nearly as much as simply doing a motor swap...

[RobertK]

Probably the most common engine swap available for E30s

BTW.. it was Racing Dynamics that orignally made the 24v Head.

[iflytii]

Probably the most common engine swap available for E30s

BTW.. it was Racing Dynamics that orignally made the 24v Head.

Thank you for correcting me. As soon as I typed that I started looking for the pics and it slowly dawned on me that it wasn't acs who produced them...

http://www.strictlyeta.net/images/rd24v01.jpg

edit: another pic
http://www.strictlyeta.net/images/rd24v02.jpg

[DirtDog]

did they ever mate that 24v head with their ITB that they made for the m20?

[newfan]

someone here has that 24v head but i forgot...

[AndrewBall]

Don't know if any of you guys remember that (edit - see below) RD made a 4 valve head for the m20 motor. Unfortunately they destroyed the castings and recent inquires have concluded they have no interest in reproducing it as it would cost nearly as much as simply doing a motor swap...

they are right being in the metal business i know what it costs to make a mold for a casting. Let alone the tooling for it after. Once made it would be very very easy. only problem is if the head your selling costs $2000 you would probably spend $12000 in prototype work and such. Also you need the equipment Oh and another thing having a new head cast in this day would cost 3x's as much as it did 2 years ago. The price of most metals has gone up by more than 300% in the last 18 months. They have done the math and they know that for every 10 E30 Owners that say they will buy one only 2 will. I have the equipment to make a 24V head, but i dont have the engineering background to do it and i dont have the money to go about doing it. Oh Btw $12000 is only to get the mold and everything made, that doesnt include having a foundry to make the castings, and a machine shop. your looking at almost $500,000 in machinery, plus about $100 an hour to operate them. So yes unfortunately its not cost efficient. But if someone with the background can figgure out the M50 head timing case then maybe it can be done. Remember to look at the M42 and S14 engine they maybe similar and have something that can adapt to an M20 better.

[delphini]

Gosh If I Could Only Had One .... Or Two .....

[3shwenty8]

so does that mean you CAN adapt the m50 head to the m20? or not.....btw........is there any CHEAP engine component swap you can do with the m20, involving relativley low modifications.........??????

[joeuser528e]

Nothing that will get you much HP. Maybe a well done e/i 2.7i stroker would net you bit of power. I guess you'd call that a head swap or a block swap, depending on whether you've got an e or i at your disposal.

[3shwenty8]

so we cant like take the head off of the 525i? or 530i 535i? i know the m20 in the 525i has more HP ouput? any clues..............? just random thoughts

[AndrewBall]

i think the 323 head is the one you want. combined with high compression pistons and cams you would have a bad ass litte motor. Even better if you gave that 323 head a valve job and porting.

[3shwenty8]

what about JUST the 323 head? any hp bumps?

[AndrewBall]

i dont know ive never done it. Some one here will know but i think it does. Larger ports and valves than the standard 325i head. I forget the part number on it. But like most mods on M20 it wont yeild much power unless combined with everything. If your going to get a higher flowing head (ie porting) your gonna want to get rid of that AFM and get an MAF system and either ITBs or a BBTB. Along with maybe larger injectors or just bumping the fuel pressure on the stock ones up. Alot of people say 19lbs injectors but i havent seen and A/F charts to really determine if they are needed. All the charts i have seen are really scaled down to smooth it out and make it look better. When i get to putting the MAF in my car we will test 19lb/hr injectors vs just bumping the fuel pressure on the stock ones and seeing what we get. I have a feeling that with out porting and an extrude and honed intake manifold or ITBs im not going to be getting enough air to feed 19lb injectors at the ratio that will make optimal power. I spent 9 hours on the dyno in my M3 finding also 40hp and 40ft.lbs just from chip tuning of the air fuel ratio. The same will go for my m20 when i get to it.

[3shwenty8]

ebay and junkyard here i come!:eek:

[Teaguer]

Its threads like this and the responses in them that keep me coming back for more .
Well ..maybe not really . :rolleyes

Many people forget ,or more likely never knew, that the US's very own Callaway , yes Reeves Callaway, developed and marketed a 4-valve M20 head back in the E21 323 days .

[jjgbmw323]

Its threads like this and the responses in them that keep me coming back for more .
Well ..maybe not really . :rolleyes

Many people forget ,or more likely never knew, that the US's very own Callaway , yes Reeves Callaway, developed and marketed a 4-valve M20 head back in the E21 323 days .
Yes there was a prototype e21 head and also a prototype BMW m20 e30 heads but IIRC they never made it into production.

[Teaguer]

Yes there was a prototype e21 head and also a prototype BMW m20 e30 heads but IIRC they never made it into production.

Yeah I'm definitely not saying that they were all over the place or even ever really for sale .
But I was pretty sure that there were "several" of them running around back in the day .

The main article that I rember reading waay back then mentioned that the writer took a customers newly finished 323 out with the then dubbed "quad" head .
So they definitely made it seem that at least a handfull of them were made and made it to the streets .

[DirtDog]

So they definitely made it seem that at least a handfull of them were made and made it to the streets .

So do u think that there some grandma somewhere cruisin in her e30 pimpin a 24v m20 and she has no idea:eek:

imagine buying an e30 and going to do a valve job and.. WTF where these 12 extra valves come from

[xLibelle]

if the e30 boards saw an RD m20 head come up on ebay, what do you think the likely bids would be?

i dont know what i would do with it because i have other projects going on but... to have such a rare item, i have no idea what my first bid would be

[lachssilberbim]

So do u think that there some grandma somewhere cruisin in her e30 pimpin a 24v m20 and she has no idea:eek:

imagine buying an e30 and going to do a valve job and.. WTF where these 12 extra valves come from
......Is that why those are there? :devillook

[rhino5]

So do u think that there some grandma somewhere cruisin in her e30 pimpin a 24v m20 and she has no idea:eek:

imagine buying an e30 and going to do a valve job and.. WTF where these 12 extra valves come from
heh, the first time she sneezes and rear-ends the car in front of her....she'll know :stickoutt

[Aussie323i]

Oh maybe my soul.

[jjgbmw323]

if the e30 boards saw an RD m20 head come up on ebay, what do you think the likely bids would be?

i dont know what i would do with it because i have other projects going on but... to have such a rare item, i have no idea what my first bid would be
If I got it, I would try to have it reproduced. We have better techonolgy today so why dont we have this head. Imagine a 3.0 M20 stroker with that head?

[xLibelle]

you are so right.

[AndrewBall]

if it was on ebay you let me buy it so i can copy it and make a shit load of them.

[deathray187]

So do u think that there some grandma somewhere cruisin in her e30 pimpin a 24v m20 and she has no idea:eek:

imagine buying an e30 and going to do a valve job and.. WTF where these 12 extra valves come from


nope, grandma probably forgot to check her coolant and cracked the head about 5 years ago, the car was crushed and sent to china and has since become razor blades and cheap trinkets sold at amusement parts.

[mavrikno13764]

sadness =( i bet all of us would prefer twin cam over single...

as i said before, TWIN CAM FTW!

[deathray187]

twin cam is not difficult to do, just get an M50 and a tranny from an M42 equipped 318, add needed conversion parts and enjoy

[mavrikno13764]

the m20 tranny doesnt bolt up?

[Eurospeed88]

I remember reading somewhere that that RD 24V head was never actually even produced. I could be wrong, though.

[Stück]

i know the m20 in the 525i has more HP ouputWrong. Identical engine/output.

[mavrikno13764]

so m20 tranny fits on the m50?

[Stück]

It bolts up yes.

[mavrikno13764]

awesome sauce! im planning to do a tranny swap for my car with the m20... is there a better tranny i can get that can bolt up to the m20 and the m50? (for future reference)

[deathray187]

how about a bit of research there first bucky, the m50 and the m20 sit at different angles, while the bolt patterns are the same you have to modify mounts for the m20 and modify your linkage for the shifter.

[Herb]

deathray187 said m42 trany, to the m50, NO. Their info has been good so far so I'm sure just a typo.:)

[deathray187]

deathray187 said m42 trany, to the m50, NO. Their info has been good so far so I'm sure just a typo.:)


no, not a typo. I saw one in person, it was a direct bolt up.

do not question the Deathray :devillook

[Herb]

I'll agree to disagree, I thought I read it didn't line up and durability issues would concern me if it did. Lost me on the TRH... no compendo.

OT: Nice car I have a '90, just switched to satin black mirriors and my "new to me" m-tech I spoiler, repainted the rubber but the plastic needs to be paint matched (will do when resprayed).

[deathray187]

yeah they bolt right up, there's another guy who runs an m50 powered e30 with the g240 for a hard core autocross car, he apparently blows 2 transmissions a year but he drives that thing HARD. so it would seem for street use it would be just fine

[mavrikno13764]

awesome! so if i get the tranny swap now then engine later its not a waste of money! sweet...! Thanks for the help guys!

[deathray187]

-sigh-
the getrag 240 transmission will not bolt directly up to your m20

[someguy2800]

Any way to put an m50 tranny onto an m20? :devillook I'm thinking 6 speed e30!

Also I should think that today they would be able to machine a 24v head out of billet aluminum? At the time they designed the old 24v head I don't think they had the cnc technology to be able to do it. I know they make cnc billet alluminum heads for motorcycles. :confused

[digger]

Any way to put an m50 tranny onto an m20? :devillook I'm thinking 6 speed e30!

Also I should think that today they would be able to machine a 24v head out of billet aluminum? At the time they designed the old 24v head I don't think they had the cnc technology to be able to do it. I know they make cnc billet alluminum heads for motorcycles. :confused

thats a shit load of machining

[putnampunk]

Yes there was a prototype e21 head and also a prototype BMW m20 e30 heads but IIRC they never made it into production.

Maybe because right about that time... a factory 24V I6 came out.

And you guys might like the Diblas ITB's...like if you were limited by class... or real "classicists" or whatever. But BMW made their own ITBs on certain engines. Put those in.


All this M20 talk is worthless. It's a 20+ year old engine design. Install a newer one if you want to throw $$ at a more powerful engine, or just be happy with the torque, power, and feel of a near stock m20b25. (Or shove boost down it's head restrictions...)

[ianfreeze]

hello hello, I know this post is more than ancient... but I was watching something about the M70 in the 850ci and it got me thinking. If the M70 is essentially two M20's jammed together and it's possible to put an M50 head on an M20, then isn't it possible to put two M50 (or even S50) heads onto an M70 and get an all aluminum DOHC v12? Strap on the ITB's and while you're not in the ballpark of an S70/2... you're in the parking lot of the stadium right?

I am aware that this is all fantasy... but somewhere in the depths of my heart I want it to be true.

This is my first post. I'm Dan. Hi everyone.

[82eye]

high dan. ��