Agustín and Anja

[Armichy]

Hi guys, i've been reading up on this forum a lot in the las couple of years, and decided to introduce myself. My name is Agustín, i'm from Uruguay.

Currently i have an e21 euro(hope that´s not a problem) with a really tired m20b20, the carburated one. I had the car for 4 years now, her name is Anja, and so far she's been upgraded a lot, 5speed overdrive getrag, 3.64 LSD, 2 years ago i converted to EFI, stock m20b20 intaje manifold, 19lbs/h mustang injectors, and a megasquirt ms2. This year was quite more fun, i upgraded to ITBS, borrowed(stole) the idea and went on with the Suzuki GSX600 throttle bodies, and as i kept the dizzy... it sucked, lost 40whp... so naturally i converted to wasted spark and it is a lot better, it is still on a base tune, but it feels and sound a lot nicer.

Next project is the m20b28 stroker, i've beer reading a lot on this matter, and recently bought ALL the age old spares that were burried in the back of my local BMW mechanic's shop with a friend, among this parts, came 2 forged cranks, which rsearch on the casting numbers revealed were m51 cranks(2242898 C38), and a set of m20b25 short skirt pistons, which my trusted machinnist said were perfect for my build... if i was building wind chimes or ashtrays...
Nontheless, i'm still hellbent on building the b28 stroker, as i already have 130mm rods and an 82.8mm crank.

Well... it's been a pleasure to introduce myself to you guys, and if it is permitted i could upload a couple pics of little Anja!

[iXguido]

Welcome Agustín!

I’d love to see pics of your e21 and the gsxr itbs.

Don’t worry, e21’s are allowed here. People post pics of e36’s frequently and they don’t get banned, so your e21 is very welcomed.

[Armichy]

I've made progress, just recently acquired a set of m52b28 pistons that are in very good shape, paid 330 US dollars for them, to put you in perspective of how tough it is here to get parts... y went through 2 set of late style m20b25 pistons, and my machinnist rejected them both...

To sum up:

M51 crank-- check
m52 pistons (and rods)-- check

the next concern is what to do about rods, y have my b20 130mm rods currently running in my car, and the very nice 135mm (forged as the internet consensus seems to be) m52 rods, acorrding to my math i have 2 possibilities:

A- 31.8(M52 piston compression height)+130mm (b20 rods)+ 41.8(m51 stroke/2)=203.2mm wich would put the piston's crown 3mm below the deck

B- 31.8(M52 piston compression height)+135mm (b28 rods)+ 41.8(m51 stroke/2)=208.2mm wich would put the piston's crown 2mm over the deck

I've read these pistons have a thick head (as well as most m20 builders i know) son shaving thos 2mm and machinning the valve pockets with my friendly work machinnist wouldn't be an issue, but the whole strapping a turbo on top of shaved pistons does not really convince me that much, aside from the really high CR(about 10.5:1 according to one of those cr calculators from one of the threads that came up on my research.

ideas? thoughts? please refrain from the "just swap an s50 and save a lot of money argument" i think there are 4 m3's in the whole country...