M50B25 tu 2.8l turbo build thread. (e36 4/dr.)

[northeaste36]

I am going to basically lay out what components have been selected and aquired, and which are still to be selected.
Hopefully some of you guys who are interested in engine building can help me through this. I am here every day but post infrequently.
The car is already stripped to the tune of, say, -~350 lbs. It is likely I will install the motor N/A, perhaps with a reduced C/R; then I will sort the car out before the custom turbo system (of my own design) is installed.





Components in hand so far:
Alpine White 1993 325i

*M50B25 tu block & head*

-I am currently in the process of porting the head myself, as well as smoothing out casting flash from coolant passages in the block & head

-I think I want to stick with an 84mm bore. I need to decide on the head gasket eventually.

-Opinions on a "plateau hone" with wisecos?

*84mm stroke forged steel crank from M52B28 (New std. OE bearings.)*

-The journals are perfect. The crank has a bit of an oil coating which is good, but can I just hot tank it when i'm ready to install, or should it be polished?

-Is any modification of the oiling holes in the crank/bearings advisable?

-This crank is from an OBD2 vehicle, meaning it had the integral/internal trigger wheel. I am going to use an OBD1 413 DME. Any concerns with this?
I do not have the trigger wheel anyway, so I have balance concerns due to it's absence. I suppose since I am using Eagles/Wisecos the assembly must be balanced anyway. Who is able to balance my rotating assembly?

*Ferrea Ti springs, Ti retainers, std. height seats*

- I think I will just use my OE valves, even though they are all about 2-6 ten thousandths below specified outside diameter. Besides that, they look great, and the guides are within spec. Will this burn oil if I am say, .0006 greater clearance total than spec? (new seals obviously). I have heard you can ream guides to basically hone them in a little, to get a few more miles out of them.

- I am blending the guides into the port ceilings.

- Can I use OE steel locks on Ti retainers? It does not seem ideal to have steel locks on Ti retainers off the top of my head, but somehow I think they only use steel for valve locks (keepers). Are there any other valve locks made? Do ferrea or supertech valves come with valve locks, or available seperately, compatible with OE valves?

*ARP 10mm head studs, main studs*

- Does anyone know the thread pitch of the head and main studs, so as to aquire the appropriate thread cleaning chasers? (or even where to order the right cleaning chasers?)

*Eagle 135mm con-rods, ARP bolts*

- I got a wicked pissah ARP billet rod bolt stretch gauge if you are doing a build in new england I will bring it over. A stretch gauge is the most precise way by far to install rods. (I live in the woods and no longer know anyone).

- I also just got a Comp Cams metered buerett (sp?) set up for cc'ing. I am not sure if it is standard practice, but I was planning to monitor port volumes during porting to make sure they are all the same volume, as well as taking various internal diameter measurements with telescoping gauges. This I will also offer for usage while I am present.

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So far, besides machining, I need to choose pistons. I am planning on getting Wiseco forged pistons, 84mm bore. It's tempting bore out the block for an oversquare config of 85-87mm bore/84mm stroke, because I want this thing to be able to rev marginally higher than stock, plus the increased displacement; this is going to be a turbo build, so the few cc's I would get are not worth sealing problems, but I like the idea of reduced side loading of the piston.
If you look at the piston chart for Wiseco / BMW (in which I believe to have found a couple technical errors, i.e. I am hesitant to trust the stated specs for my build, but I will measure whatever comes in the mail/to the machinist.
Since I am using a M50B25tu block with an 84mm crank, and 135mm eagle rods, I need to know if the M50b25 and M52b28 blocks have the same deck height. What part number wisecos are compatible? What C/R(s) can I get?

For your interest, I will list other components aquired so far, to give you a general idea of the car as a whole:

-M X-brace
-Powerflex rtab, rear subframe bushings. Non-m Meyle front control arms. I understand Lemforder fca's would be better.
-Bimmerworld delrin offset fcabs. I would love to know:
*exactly how to orient the offset orientation
*exactly what drill bit to use for the lollypops for set screw install. What to use for a set screw.
-Bimmerworld front and rear subframe reinforcement plates.
-Rogue Engineering rear shock mounts, higher durometer(<--I hope) cylindrical tranny mounts. Stock engine mounts. I will see if this soft stuff works OK. Comfort/NVH are of little concern.
-SPC adjustable steel rear control arms ($180 at bimmerworld!)
-Stock 93 325i 5speed getrag; We'll see if it survives the torque of jesus' turbo-zeus power!!! Stock flywheel. Undecided on clutch, probably something from South Bend clutches.
-All new stock gaskets, seals, hoses, belts, chain guides/tensioners. Anyone have an opinion on endless timing/oil pump chains versus with a master link?
I believe the oil pump chain is only available with a master link, while the timing chains are available with or endless.
The OE chain supplier (Isis I think?) also makes a "racing version" (best price I have found on the "racing" chains is at pelican parts). Are these worth it?
- I am going to try and fabricate a splitter and flat bottom the car. Any tips or insight on making the car flat bottomed underneath? (to negate lift)

Thanks, any comments are welcome.

[northeaste36]

Today I am skinning the trunk lid.

[Concentric190]

-This crank is from an OBD2 vehicle, meaning it had the integral/internal trigger wheel. I am going to use an OBD1 413 DME. Any concerns with this?
I do not have the trigger wheel anyway, so I have balance concerns due to it's absence. I suppose since I am using Eagles/Wisecos the assembly must be balanced anyway. Who is able to balance my rotating assembly?

need to get a obd1 dampner & obd1 crank sensor. the internal sensor just stays unused

[northeaste36]

need to get a obd1 dampner & obd1 crank sensor. the internal sensor just stays unused

I have nothing but OBD1 components, excepting the "OBD2" 84mm B28 crank, for which I never recieved the internal trigger wheel or sensor in the first place. Sounds like I am set as far as that.