M50 stroker or M20 stroker

[mr2peak]

i don't want an S5X engine they are expensive to maintain and services thats why for the M50 setup i will go with the non-vanos M50 because it is more simple

How much maintenance do you think you can accomplish for the price of building a stroker?

[BMW B3 2.5]

guys I AM NOT IN THE US and yes euro S5X engines with low mileage are getting hard to find but i can get an M50 NV for around 600 $ thats why i would like to build a stroker and as for the M20 i am just curious what numbers can be reached on that build so can anyone tell me ?

[bangn]

Its funny people are willing to ride off the M20 so quickly, for the effort involved I dont think the m50b25's go that much harder, in fact I was quite disapointed. you can still get more power than you can use from an M20 reliabl if you put a snail on. Remember tho an M50 is going to be more expensive to rebuild than an M20. Valvetrain is twice the parts.

[BMW B3 2.5]

do you have any idea what HP numbers i can get from either of the builds ?

[slammin.e28]

M30 all day. If you're not in the US then you probably got the good ones, but of course, ........ probably didn't get anything good from BMW.

[bimma360]

So i was thinking about building an M50 stroker but one of my friends is telling me that i can get around 220 HP from my M20 that is in my car now so can any one tell me what setup of the two is better and which one would cost less ?

M20 setup:
M20B27 eta block with eta crank
282 ro camshaft
a custom chip with a 7000 rpm redline
a ported and polished head
headers bigger injectors and modified MFA
EDITED: M20B25 pistons and if i go with this build may get a 524Td crankshaft ( forged )

In this setup, if you are using eta rods with your B25 pistons you'll have very low compression (7.5:1). Using both B25 rods and pistons you'll need to have the top of the pistons machined down and have the valve pockets recut. I've read that this yields a pretty high compression, someone who is more familiar with this setup can chime in.

220BHP (assuming thats what you meant) is about 176-187WHP. I think something in that range should be doable with a high compression 2.7L.

[nando]

one problem with a full out build of an M50 is the cost of the head.

Take the cost of building up an M20 head, and multiply it by 2 or 3. there are twice as many parts and things such as cams are significantly more expensive. if you're building a stroker and using stock cams, you've just wasted your time.

also, if you're going to build a full out stroker on the basis of you can get a block for $600 your head is in the wrong place.

also for an M20 stroker you don't really need or want a TD crank. it weighs more and costs more for no real benefit. if you're going to bother you would be better off fitting the biggest stroke you can get to have the most potential torque output.

focus on the head. the cost of the bottom end is going to be nothing in comparison to a properly built head, and that is where you will see the difference between a motor that makes 170bhp and one that makes 240+.

[BMW B3 2.5]

In this setup, if you are using eta rods with your B25 pistons you'll have very low compression (7.5:1). Using both B25 rods and pistons you'll need to have the top of the pistons machined down and have the valve pockets recut. I've read that this yields a pretty high compression, someone who is more familiar with this setup can chime in.

220BHP (assuming thats what you meant) is about 176-187WHP. I think something in that range should be doable with a high compression 2.7L.

so for the M20 if i port and polish the head keep the M20B27 pistons and just throw in a 282 ro camshaft with larger injectors will the engine have 200 HP ow more ?

[Bullet Ride]

M20 stroker all the way. My 2.8L stroker made 183whp/194wtq (running rich because of a bad O2 sensor) with a schrick 284 and Bavauto headers. However the shape of the curve lead me to believe that my cam was too advanced. I'll be going back to the dyno in 2 weeks with some retarded timing and a better fuel map hoping for something like 190whp/190wtq.

The only head work done was gasket matching the exhaust ports. Combustion chamber and intake side was stock except that I have no AFM because I'm running MS.

There's a number of good build threads out there (one of them is mine ;)), just google M20 stroker.

[BMW B3 2.5]

one problem with a full out build of an M50 is the cost of the head.

Take the cost of building up an M20 head, and multiply it by 2 or 3. there are twice as many parts and things such as cams are significantly more expensive. if you're building a stroker and using stock cams, you've just wasted your time.

also, if you're going to build a full out stroker on the basis of you can get a block for $600 your head is in the wrong place.

also for an M20 stroker you don't really need or want a TD crank. it weighs more and costs more for no real benefit. if you're going to bother you would be better off fitting the biggest stroke you can get to have the most potential torque output.

focus on the head. the cost of the bottom end is going to be nothing in comparison to a properly built head, and that is where you will see the difference between a motor that makes 170bhp and one that makes 240+.

if i go withe M50 build i will Regrind the standard cams to 254°/244 and if the stock internals are in a good shape i may reuse them
and do you have any idea what is the maximum HP that can be reached by an M20 engine if i keep the bottom as it is or maybe use other connecting rods with the eta block ,crank, pistons ,282 cam with headers and larger injectors ?

[BMW B3 2.5]

M20 stroker all the way. My 2.8L stroker made 183whp/194wtq (running rich because of a bad O2 sensor) with a schrick 284 and Bavauto headers. However the shape of the curve lead me to believe that my cam was too advanced. I'll be going back to the dyno in 2 weeks with some retarded timing and a better fuel map hoping for something like 190whp/190wtq.

The only head work done was gasket matching the exhaust ports. Combustion chamber and intake side was stock except that I have no AFM because I'm running MS.

There's a number of good build threads out there (one of them is mine ;), just google M20 stroker.

what is your M20 build ? can you give me a link or more details ?

[Bullet Ride]

what is your M20 build ? can you give me a link or more details ?

There is this nice tool at the top called "search" you know

http://www.r3vlimited.com/board/showthread.php?t=243359

[bimma360]

so for the M20 if i port and polish the head keep the M20B27 pistons and just throw in a 282 ro camshaft with larger injectors will the engine have 200 HP ow more ?

Unfortunately no, eta pistons, eta rods, and B27 crank will still lower your compression. You will be around stock m20b25 hp. You will probably get more out of your B25 bottom end with that head work.

Here is an excerpt from another thread: http://www.r3vlimited.com/board/show...&postcount=308

This was using a Myster-e head which sounds like similar to the head work you have planned.

[BMW B3 2.5]

Unfortunately no, eta pistons, eta rods, and B27 crank will still lower your compression. You will be around stock m20b25 hp. You will probably get more out of your B25 bottom end with that head work.

Here is an excerpt from another thread: http://www.r3vlimited.com/board/show...&postcount=308

This was using a Myster-e head which sounds like similar to the head work you have planned.

if i change the connecting rods an keep the crank and pistons ? for example can i use M50B25 rods ?

[F34R]

if i change the connecting rods an keep the crank and pistons ? for example can i use M50B25 rods ?

Go to the engine tech section and please for the long of all that is good SEARCH. It has been covered ten fold on anything you have been asking. You are not even asking hard questions, I am sure there is 1k+ threads started by people just like you in there.

How about you just put an s50 in there? It is just a bored out m50 with s50 cams. You WILL spend more building an m20 or m50 stroker than swapping in an s50.

Search my builds...built an m20 and it was a lot more than a s50 with transmission.