My m10b engine thread

[Jean]

Alright, so a couple more bolts and it's all 100% apart. I am dumb and going to go through with this rebuild just because lol

I am going to drop the block off this week for a machine shop to blast/clean and check. They would know what to do, but to not sound like a clueless n00b what should I ask them to do besides cleaning it and rehoning the cyl. walls ?

Should I bring the bare crank also to check what bearings I need to order and what other things can be done to the crank ? I am not trying to spend a lot of money on it as it's pointless, I am only doing this as a leason and to build a little relationship with a shop.

Rods I should be able to re-use, I'll order new bearings and new oil pump, chain and tentioner.

What should I do with pistons ? Order new oem pistons or is there a good deal somewhere on new maybe lighter pistons that won't require any modifactions to the head chamber etc?

This is going to be my first engine build / swap to learn on before I touch the m30.

[Jean]

Another view of crank -







Piston rings on 3rd cyl piston









all 4



bare walls -



oil pump, chains, guides, cover.

[Jean]

Here is the bottom end and it's parts, next week I'll take it to a machine shop for cleaning and inspection first.

Timing chain cover -


front side view, I broke one of the chain guides in the process of moving the block ....








rear seal, last left to remove -




cyl 1


cyl 2




cyl 3




cyl 4

[Jean]

Right, but would it be worth the hassle and is there any benefit to longer stroke with FI ? or am I fine with forged pistons/rods , stock crank, and basically stock bore but maybe 0.5-1mm over ?

[HST]

I think that the 2002 crank would give you a longer stroke, and it is forged.

[Jean]

Got the oil pump, crank pulley out. Have two options now:

1) take the whole thing to a machine shop to inspect / clean , put new seals, drain plugs, bearings and re-use stock rods and pistons

2) take the bare block only, have it cleaned , new drain plugs, install crank with new bearings and front/back seals, machine / hone block for new pistons (have yet to order), maybe 1 over ?


Here is another question, I was discussing this with my co-worker who is big in drag racing....

the idea of "high bore vs. longer or shorter stroke" , and when one should be picked over another. to my understanding, longer stroke = bigger bang = more torque, also = lower revs with longer stroke compared to short stroke. With FI, I was told I am better off leaving the stroke alone and just going with the next oem size up in bore to keep everything as strong as possible ? Also, to stroke I wouldn't be able to use stock crank, and would need to go with custom crank + pistons and/or rods, basically crank works together with the longer/shorter rods or pistons and is part of the equation. Since I am going FI, I don't see a benefit to going the route of stroking the engine. I am thinking about going maybe 1mm over in bore to gain just a little more CCs.

Does this make sense, any suggestions ?

[Jean]

No updates yet as this was an autocross weekend for me, but a friend and some air tools got the stupid crank bolt pulley out . I was going to drop the bottom end off but was told it would be a good idea to have custom pistons/rods on hand so that the shop can machine the block to the right pistons. I was originally going to drop the block off for cleaning/testing and then would get the rods and pistons (h-beam, je). Once I figure out what compression ratio to shoot for and what pistons / rods I would want to order..


I need to re-think this, and figure out if it's not going to be much more to shoot for about 300-400hp instead of my original goal of 200-250. The custom forged pistons and h-beam rods should be good for more than 200-250 hp safely, and if I spend that much money on them I wouldn't mind getting the most out of it.

Doable or is the head not going to like it ?

[Jean]

Just picked it up today, only needed new valve seals, rest was in good condition, total cost $290.




This coolant hose connector is not perfect but looks like this part can be replaced with new.






Cleaned oil pan and manifold.



Next I need to get the TB and injectors cleaned and get the gaskets / head bolts / and injector o-rings. Should I even bother with the bottom end rebuild ?

[iNetMANN]

ok, I have an 84 318i, its manufacture date is nov, 1983, will it have what would be considered an early m10 block?

No, use 2002 block. I used a late 70's block w/2002 crank and 92mm flat top wiseco pistons. Plenty thick on the old blocks to even go with 93mm...
Rockers/springs are the week point on the M10 at high RPM's so use either aftermarket rockers/springs or arm locks. I can regularly peg my car at 7000+ RPM with stock rocker/springs and the arm locks keep them from falling off the valve stem.

RODD

[Rocla]

ok, I have an 84 318i, its manufacture date is nov, 1983, will it have what would be considered an early m10 block?

No. E30's never had "early" blocks from factory. And I'm not sure if all e21's had the "heavy" version, all e21's DID have the old pattern motormount, some the latest had even dual pattern for right mount.

[new2bmw]

early block

ok, I have an 84 318i, its manufacture date is nov, 1983, will it have what would be considered an early m10 block?

[Rocla]

Any suggestions on 91mm pistons and matching set of rods ? Is the wall thickness on a 318i block the same as on the 2002 block, I thought someone was cracking a couple of blocks by going wider...i might be wrong though, you are the man when it comes to the m10s :)

2002 block weights more than e30 block... so most likely wall thickness is bigger, most hardcore m10 builders use early blocks and claim that they are better.

[Jean]

Any suggestions on 91mm pistons and matching set of rods ? Is the wall thickness on a 318i block the same as on the 2002 block, I thought someone was cracking a couple of blocks by going wider...i might be wrong though, you are the man when it comes to the m10s :)

[Good & Tight]

Am I not better off leaving the bore alone to not make the block weaker when boosting ?

Hell no, hog that bitch out to 91mm.

[peete]

I'm pretty sure the nut on the oil pump gear is reverse thread. But not 100%