M50 stroker or M20 stroker

[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 ?

[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+.

[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.

[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.

[BMW B3 2.5]

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

[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]

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 ?

[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?

[Wh33lhop]

Frankly there is no reason to go for an NV motor over a Vanos motor. There are no performance benefits.

[FredK]

It's possible the original poster does not live in the US, in which case the US S50 would not be nearly as available.

You will clearly have the most power with the M50 stroker engine, and it will be quite a bit more expensive than building a 2.7L M20.

Depending on the price of tuning, it may make sense to build an M50TU 3.2L stroker (M54 3.0L crank, 86.5mm pistons, 135mm rods). That way you can buy an off-the-shelf tune for around $250 and it will already be 95% optimized.

[E30 Wagen]

M50 stroker is what I would do.

[Ryann]

I've got a 24v stroker build in the works. TU block bored to 86mm, stock refurb'd TU head, m52 crank (84mm stroke) using 140mm TU rods and custom pistons. Shooting for 200/200, thinking it will be very dependent on the tune.

Something to consider aside from the obvious m20 maintenance downsides is the m50's superior fuel efficiency.

On the other hand the m20 sounds better and isn't shrouded in plastic.

[evandael]

rated in order of coolness..

m30, m20 stroker (not 2.7i, but rather based on a s52 crank), s52/50.

it doesn't make any sense to stroke an m50 unless you have the engines laying around already.

[Herr Faust Schinken]

M30 done

[z31maniac]

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

Huh? It's not an S54.

An S52 is no more maintenance intensive than an M50 or M52 and less maintenance than an M20 since you don't have to have regular valve adjustments and timing belt replacements.

Personally, for old school cool. I'd want an M20 stroker with ITB's.