How are the internals considered to be weak, anything forged is better than cast. I have also spoken with two other boosted e36s that live local to me that say it should be fine up to 500whp, any more than that and I should consider building the bottom end which either way I have intensions of doing, just a matter of now or later
1992 325is chassis, S52B32 OBD1 converted, PnP head by PER Race engines, 5 speed swapped, coil over suspension, active autowerks cat back with straight pipes, exterior and interior fully transformed to M3 clone. Currently under construction headed for boost.... Current plans: Precision 6262, custom top mount manifold by Straightline Performance, walbro 450 fuel pump, rally road fuel rail with 8an feed and return, aeromotive FPR, miller war setup with 100lb tune
13lives, the EURO S50/S52 have forged crankshafts, but POS connecting rods & wrist pin...
US S50/S52 have spheroidal cast crankshafts, and way better connecting rods, but they are still cast rods...
Any stock M50 will be safe for 350-400whp (depending on the tune) wether it's a M50B20, M50B25, M50 with M52B28 internals...
BUT.... sourcing M20 connecting rods, and M50 NON-VANOS pistons will give you a stronger bottom end...
For a M50B20 build (i'm doing one myself right now for a friend of mine) i am using a M50B20TU engine, with M20B20 pre-87 pistons & rods.... -2.7mm deck clearance, flat top-piston with way more ring-land + beefier rings than the M50TU piston... resulting in 8.2:1 CR... and rods that are stronger that stock M50... all ACL bearings (main & rods), ARP main & head studs, MLS gasket & ARP conrod bolts....
For a M50B28 stroker build, you would use pre-VANOS M50B25 pistons (these also have a greater ring-land & beefier rings), M20B20 connecting rods, M52B28 crankshaft, all ACL bearings, ARP main head & conrod, MLS gasket/cutring...
This should get you easily into the 600hp mark until you start melting pistons (depending on the tune).... US S50B30 engines share the same length conrod as the M20B25....
So if i were to build a cheap S50 US engine, i would definately buy a 800$ piston set (any set really they're all good nowadays), use M20B25 conrods, ACL bearings for everything, ARP for everything and use a cutring or MLS gasket...
Should definately be a safe 700+hp setup...
- - - Updated - - -
S50B30, S50B32 and S52B32 all use the same rods, part no. 11241247175
So in theory, i would source some M20B25 rods.... stick with stock pistons and roll with 500whp all day !!!
You will save yourself the 600$...
ARP 201-6301
ARP 201-5000
ARP 201-4302
These are the ARP items you will need...
Last edited by DieselGhost; 10-03-2014 at 05:33 AM.
Viktor Agnar Falk Gušmundsson
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Signature idea, courtesy of 5mall5nails
When I was shopping last year, there were quality pistons plus rings plus rods combinations (like JE and Eagle) on ebay for about $1250 shipped. Pretty good deal. Lower compression at 9.0:1, 2618 forged pistons for better durability under boost, and 4340 rods. All stronger than whatever old BMW parts you might scrounge up and mix and match into something that is hopefully a little more durable that stock. And no need to sacrifice displacement down to 2.5L or 2.8L.
But if you are on a tight budget or displacement is not an issue because you care only about high rpm power or because you are using E85 and can increase timing to spool a little better, then by all means scrounge parts and do a cheap build. I like cheap builds. They show creativity and DIYness, which I like.
I have a good Idea of the direction I am going to go, I have some local support as well as my experience and knowledge plus some other engine guys here by home. I will keep the thread updated as I go along, compression and leak down test coming next and then dyno day to get baseline numbers. I want to know what the progress is before and after.
Thank you all for your suggestions, the info is much appreciated and in just a short time I have learned a substantial amount
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