Engine Build

[Gus 5]

well taking them apart was easy enough..now for the hard part!

need to go get the block decked 2mm still...but im just getting a list of new stuff i need

the bearing shells look all good and i know they were replaced not long before i got the engine..planning on leaving them in. using same crank and main bearing caps anyway.

new rings...needed? probably get 2 sets in case i break a few? any idea on $$?

that means ill prob need a bore hone..get when the block get decked

oil seals are all brand new..will re use. oil pump looks new too. as above.

obviously new conrod bolts, and unless i get head studs, new headbolts/gasket

then will need an adjustable cam pulley. pure-pf.com has them, $$ though. anywhere local or what i was thinking was to slot the stock one so it can be adjusted. only prob is that have no markings to see how much needs moving and would need to get a way to keep it there. (bolt?)

will prob give the head a light polish to smooth things out on the exhaust ports and combustion chambers. not sure if i will rebuild yet as it looks mint..all looks new. anyway to test the valve sealing? will be putting my old cam in.

when assembling can i use engine oil to lube it up or do i need something heavier like a specialist engine building oil?

i have prob missed a couple of things but does that seem about right? any suggestions would be appreciated

[Silver Fox 43]

What motor Gus?

[Gus 5]

i'm doing an M20 merger..2.7 bottom half with my spare 2.5

[Hartage 0]

Some ring suppliers recomend that you Dont Hone, and assemble the pistons and rings dry ( no oil ). So check this out before you Hone.

The cylinder head Valve stem seals are the biggest user of oil, If you were getting any smoke off the motor before, then i would do a valve grind and fit the new seals.

Engine oil to assemble is ok, I tend to put Clean grease in the oil pump when i assemble them, It makes it pick up the oil quicker when turning over the first time.

Just My way of doing it. Hope it helps.

[kerrynzl 3]

Cam lube? definately needed for start up [moreys can be used as an assembly pre-lube 'til you get oil pressure]

Pay a Motor-machinist to parrallel hone the bore [if there's any lip in the bore,it'll break your rings]

while you're at it, get a 3-angle valve seat job done [don't waste any effort on polishing the ports]

Why are you decking the block 2mm? [are your slugs that far down?] If decking the block ,check the valve to piston clearance [use an old head gasket & bluetack]

measure the bore & ring widths then ring STA [segedin Truck & Auto] they'll find a set for you [usually under $100,unless you want gapless rings]

Why do you need 2 sets of rings? are you installing them with your Ball-joint hammer? [Leave them in the SUN for an hour then you can SPREAD them with your fingers, never try & wind/twist them on cause they'll break] Practice this with your old Rings First, It's easy.

You're not building a Sleeper Engine for this new BMW racing class are you?

[Gus 5]

thanks guys

will be checking how much i need to deck block, but 2mm is what i have read. comes from using the 325i facelift pistons with the longer stroke crank and shorter rods..end up down bore a little.

hammer has been surprisingly useful!

spreading sounds good...the twist in does make it seem fragile..have been playing with old ones

not a sleeper engine..just doing it for the hell of it as i have the bits and want to build an engine..havent done it yet!

[skidz 196]

When engine builder assembled my 2.7 engine, he found there was no need to deck the block.

That was same deal - 2.7 crank and rods, 325i pistons, block and head.

So no need to adjust camshaft timing.

[Gus 5]

really? that would be awesome. looking at the two pistons/rods it looks about right. will test fit them when i can and see...fun times.

how does yours go? FL or pre FL pistons?

[Hartage 0]

It goes too damn fast!!

126.6 at manfield.

really? that would be awesome. looking at the two pistons/rods it looks about right. will test fit them when i can and see...fun times.

how does yours go? FL or pre FL pistons?

[skidz 196]

how does yours go? FL or pre FL pistons?

Goes alright (Hartage is just jealous)

It was a Facelift Motorport engine we started with, which from memory have different pistons.

The rings were expensive. I think they had to come from Australia and were around $350 plus GST.

[Gus 5]

through BMW? why so expensive? will try dummy fit a conrod/piston tonite and see what happens

what rods are you using? i was planning on the 130mm ones..not the 325 135mm

[kerrynzl 3]

The rings were expensive. I think they had to come from Australia and were around $350 plus GST.

ACL make a wide variety of rings [so do Hastings]

all you need isthe bore diameter & ring width and they'll find them

Segedins Truck & Auto do ACL .... Pioneer Equipment do Hastings

otherwise Johnsons Piston Rings in Penrose will cut you a set [cheap]

While I'm here I'm curious about the F/L pre F/L pistons question[assuming they have the same bore size] did they change the rod length [& piston compression height] does this apply to the 2.0 M20 as well?

[petone 0]

While I'm here I'm curious about the F/L pre F/L pistons question[assuming they have the same bore size] did they change the rod length [& piston compression height] does this apply to the 2.0 M20 as well?

I've only heard of the 2 conrod heights of either 130mm or 135mm. Not all M20 blocks are the same, some e34 blocks have a different dipstick location and the blocks with 80mm bores lack steam holes. I haven't seen anything about different deck heights.

[Gus 5]

as far as i understand it:

the 2.5/2.7 m20 have same size bores (83.9mm) and different strokes (81mm for 2.7, 74mm??? for 2.5)

the pre FL 2.5 pistons make a compression ratio of 9.7, the facelift 8.8. kinda hard to describe but from what i remember seeing them the facelift piston part that is concave is deeper. i would use pre FL pistons, but i kinda want to keep my current pre FL engine intact (as a spare when my 2.7 doesnt work haha) and using FL pistons does not rule out a turbo usage further down the track (i think using the 2.7 crank may increase it to 9.7ish)

the problem im going on what ive read, which a lot seems BS...will be interested to see what the actual story is. as 2 articles i have read (one in Total BMW, you would think respectable) say the 325i pistons end up 2mm down in block.

the rod length is easy...2.7e and 2L had 130mm..325i had 135mm.

[Gus 5]

well learnt a few things..

325i pistons definately sit 2mm down in the bore

piston rings easy to break when cold

and i THINK nz new cars have same as pre FL pistons (have heard this rumour before)...my pistons have a longer skirt. which i found out the hard way.

so i MAY need a spare 325i piston? just the one thanks part numbers on inside...Mahle A1 84v128 then on the other side C041

[Guest Spargo]

What sort of "squish" number are you aiming for?

[petone 0]

so i MAY need a spare 325i piston? just the one thanks part numbers on inside...Mahle A1 84v128 then on the other side C041

If you get desperate let me know, I may have the right one back home.

[Gus 5]

cheers brother...will do

squish? something soft? same as stock?

[kiwipetrolhead 1]

It goes too damn fast!!

126.6 at manfield.

really? that would be awesome. looking at the two pistons/rods it looks about right. will test fit them when i can and see...fun times.

how does yours go? FL or pre FL pistons?

Hey Hartage, is that 1 minute 26.6 seconds? And on the original circuit?

Tell me that and I'll tell you why I ask!

Cheers

Paul

[mops 4]

Hey guys.

I'm preparing for an m20 stroker turbo build myself.

just picked up 2.7 from pick-a-part last weekend. I got 325i, so the head is there.

re m20b25 pistons, you are right early ones were 9.7:1 (i got these) and later ones are 8,8:1.

here is all the info

http://www.bmwccn.no/rogaland/Mahle_m20.html

but, i have heard the following things (cannot confirm)

e blocks are 0.5mm taller than i blocks.

e rod (and m20b20 rod, and m5x seriess 23, 25, 28, s5x) are 130mm

i rod is 135mm

so i was thinking, e, block, e rods, e crank, i piston should result in about 8.3:1 compression which is great for the turbo. some squisch (otherwise called squench) area will somewhat suffer, but still I'm using pistons matched to the head combustion chambet, which is good (i suppose better than e piston).

aswell i head that there are two types or i head 7xx (dunno exacly what number) casting and 885 casting. 7xx casting has a smaller combustion chamber (aparently).

Hey gus, if you are buying bearings/rings, let me know I want a set of these aswell, maybe we can get it cheaper on a "m20 rebuild group buy"

aswell i'm looking for somebody experienced in engine rebuilds to look over my shoulder while i rebuild my first engine. i can provide beverage of your choice/food of your choice/petrol money to cover expenses of getting here anyone keen PM me