building a 24v DOHC engine

[lifeiskaos]

Hello all. i plan on building an engine in my near future. the starting platform will be either a single vanos m50 or m52, but i have several questions. once i get the engine, i will tear it down and completely rebuild it. the engine needs to be strong as it will see lots of track time and boost after initial break in

goals:
3.0L, running megasquirt, suitable for future boosting

questions:
which engine will be easiest to start with? i've heard m50 internals are beefier but i dont know how much of it will remain. m52 is closer to my 3.0 liter goal, so that should be easier... right?

crank. i assume a standard m50 crank is out of the question for a 3.0 liter build, so can it be done with 2.8 m52 crank? or should i go with an s50/s52 crank?

rods. how long? oem? aftermarket? from which engine?

pistons. overbore, lowish compression (below 10:1). i have no problem going aftermarket, or custom, but if an oem piston/rod combo will do, hooray. if i cant get low comp pistons, i can always use a thicker headgasket, otherwise i'd rather oring the block with stock HG and studs

cams. i'd love to get some wild cams. lopey idle is fine, the higher displacement should add low end torque, and future turbo for the higher end torque, so im hoping to find nice cams that will balance out the two and give the most power with the best powerband.

ecu. megasquirt will be running the engine, but i'd be scared shitless to use megasquirt on initial startup. i'd rather use a bmw ecu (which one?) that might work with the setup, just to test the engine and break it in a little.

im sorry for all the questions, i wish i knew enough to figure it out myself, but i simply dont. i did try to search but almost all setups are different and information is so spread out that its hard to find specific answers. if you could help me out that would be great! thanks

[318isbmw]

Well an s50 is merely same block as m50 that has a different crank and rods and a bit wider pistons. So I would either start w/ m50 and get all s50 internals for it, or get an s50 and call it a day.

[madjurgen]

Youre asking very basic questions that could be answered with 5 minutes of research over on bfc. Stop being lazy.

[lifeiskaos]

or i could post on a site dedicated to e30's with owners who supposedly help each other and ask very basic questions... stop being an asshole

[lifeiskaos]

Well an s50 is merely same block as m50 that has a different crank and rods and a bit wider pistons. So I would either start w/ m50 and get all s50 internals for it, or get an s50 and call it a day.

what's the fun in starting with an s50? :D half the fun to me is building the engine, plus the combo im looking for is slightly different than a regular s50

[mentaleeill]

or i could post on a site dedicated to e30's with owners who supposedly help each other and ask very basic questions... stop being an asshole

but the engine you are talking about is not from an e30.

you are gonna want the s50 crank if you wanna go 3.0 with just a slight overbore. just get the m52 as it has forged internals and is most likely gonna be easier to find with less miles. look on bfc in the fi section and you will find rod and piston specs very easily.

[hoveringuy]

what's the fun in starting with an s50? :D half the fun to me is building the engine, plus the combo im looking for is slightly different than a regular s50

An M54 is for you!

[e30_325es]

I have the first piece to your puzzle for sale! An s50 crank! Pm me if you want it.

[PiercedE30]

Grab either M54B30 crank and get some aftermarket rods/pistons with CR of like 9:1 or get an S52 crank and aftermarket rods/pistons (both the same actually). I would HIGHLY recommend starting out with either an M50 or M52 block and only boring out to (at the most) 85mm (+1mm from stock) just to keep cylinder wall strength. That and if you are going for serious power get some 12 or 13 mm head studs and main studs, yada yada. If you go with an S50 crank and a bore of 85mm, you will be right around 2.9L.
Oh, and the M52 has forged rods/crank but not pistons. None of the factory pistons will be forged.

[BeirBrennerE30]

your gonna need 2-3 cans of high temp spraypaint for a project like this...

[Massive Lee]

The initial post is soooo funny. :giggle:

[e30s52]

or i could post on a site dedicated to e30's with owners who supposedly help each other and ask very basic questions... stop being an asshole

i thought this was the funnest post. i dont think he knows r3v yet lol.

[sikboy]

I've got a m50tu swap to start. I plan on using a z3 2.8 aluminum block and m54b30 crank and rods with custom pistons for 3.0. Should be torquey


Mr Sik

[lifeiskaos]

but the engine you are talking about is not from an e30.

you are gonna want the s50 crank if you wanna go 3.0 with just a slight overbore. just get the m52 as it has forged internals and is most likely gonna be easier to find with less miles. look on bfc in the fi section and you will find rod and piston specs very easily.

alright, i was unsure of the compatibility between m and s engines, and obd1 v obd2 etc.. a bigger crank though on an otherwise stock m52 would likely end up in valves kissing pistons, but are you saying i can use s50 crank with m52 rods and aftermarket pistons? thanks for reply

An M54 is for you!

hah, the recent m54 swap thread has drawn me straight away from that. i can build an engine, but im not ready for that much fab work

Grab either M54B30 crank and get some aftermarket rods/pistons with CR of like 9:1 or get an S52 crank and aftermarket rods/pistons (both the same actually). I would HIGHLY recommend starting out with either an M50 or M52 block and only boring out to (at the most) 85mm (+1mm from stock) just to keep cylinder wall strength. That and if you are going for serious power get some 12 or 13 mm head studs and main studs, yada yada. If you go with an S50 crank and a bore of 85mm, you will be right around 2.9L.
Oh, and the M52 has forged rods/crank but not pistons. None of the factory pistons will be forged.

thanks for the highly detailed response! god an idea of what length rods i should be looking for? very good point about the cylinder wall thickness. i will hopefully be pushing ~500bhp, so i'll want them to be strong, plus keeping room for o-rings, unless they're not as necessary as they are on m20's? head studs are already considered a must. thanks again

[lifeiskaos]

I have the first piece to your puzzle for sale! An s50 crank! Pm me if you want it.

i'll keep it in mind!

your gonna need 2-3 cans of high temp spraypaint for a project like this...

i am not kenika

The initial post is soooo funny. :giggle:

care to elaborate?

i thought this was the funnest post. i dont think he knows r3v yet lol.

good for you?

I've got a m50tu swap to start. I plan on using a z3 2.8 aluminum block and m54b30 crank and rods with custom pistons for 3.0. Should be torquey

Mr Sik

sounds fun! unfortunately i've heard those aluminum blocks+boost=bad... otherwise it'd make some great weight reduction. good luck