M20B28 is finished, and it works!

[nickphine]

Managed to finally get my engine bay painted and my freshly built 2.8 in place and the car is now basically finished. After turning it over for a minute with the coil lead off, she fired straight up and settled down to a steady idle, massive result as I was a bit worried frankly. Built from a late2.5 the spec is,

Single vanos crank
M20b20 rods
Late pistons with 9mm machined off the skirts
Lightened flywheel balanced to crank
Block machined down .5 mm to 205.5 deck height
Standard head, tested and rebuilt and valves relapped
All new seals, gaskets, shells, bolts etc
M21 hp oil pump
New BMW water pump
New timing belt kit
Standard cam with new rockers
Full btb single pipe twin silencer stainless system
Standard cam and motronic setup
Standard inlet setup

Ran out of money at the end, hence no fancy cam and inlet yet. But I have to say it pulls really well, revs very freely and lights up its rear wheels at the drop of a hat. Massive improvement over the is engine.

One interesting thing, I used a 318is radiator with it's built in expansion tank and it seems to work perfectly and looks a bit tidier. The core is exactly the same as the 325 core and temp is rck solid just below half. Pictures to follow.

[reggid]

Good to hear i am building a similar engine but will be using a ported and flowed head with 270ish cam although standard exhaust manifold.

[gooner1]

Good news Nick. My build will be very similar to yours, with the exception
of early block
H/C Pistons
325I Rad.

Did you machine the late Piston skirts as a weight saver, as i was under the impression
later pistons would not need any machining
My early ones fit fine.

[nickphine]

Had to machine the pistons to get them to fit, 9mm all the way round, quite a lot i thought, but it was the only way to clear the crank webs. Perhaps my car had a replacement high comp engine in it? No idea how to tell? I did read somewhere that there are different types of later pistons and that some need machining. One thing I remember though, is even at 9mm skim I had to ever so slightly notch the skirts to allow for web clearance, approx 1mm.

Whatever though, the end result is a surprisingly peppy engine. Ihad my flywheel lightened and balanced to the crank, and also my rods and pistons paired so they are all exactly the same weight. It revs really quickly and sweetly and is miles torquier than a 2.5. Mine just lights it's skinny tyres up at low revs in second, it's totally ace.
Also, by sticking to the standard cam and chip it seems to run faultlessly and performance is great, i'm sure i'll want more in the end, but for now i'm glad I didn't soend any more money on it. People seem to spend an awful lot of time getting theirs to run right once they get into cams and chips etc etc.

Anyway, good luck with yours, keep me posted.

Nick hine

[bridgemond]

Good stuff man. Looking forward to a few bay pics

[gooner1]

Will do Nick. H/C Piston pics, not that it matters, it sounds like you're enjoying it regardless.





[/quote]

[CHR1S1990]

One interesting thing, I used a 318is radiator with it's built in expansion tank and it seems to work perfectly and looks a bit tidier. The core is exactly the same as the 325 core and temp is rck solid just below half. Pictures to follow.

interesting, didnt think they could be used on the m20 nick. Wouldnt mind making a little more room removing the remote expansion tank myself. Pictures must follow, as you say

[BrewCity11]

We've used the 318is radiator numerous times on our project cars. It's a mix of hoses, I don't have the part numbers. Do you have them Nick?

Coupled with an electric pusher fan, it really tidies up the bay.

[daimlerman]

Always good to hear that a modified motor runs properly!

I would let Gunni have a play with the motronic,though,you will be suprised at what he can find....contact details in the traders section...

[nickphine]

Hoses wise, I just used all the standard m20 hoses, the only different thing is that there is no pipe going from the rad into the expansion tank, but this is all internal in the is rad. I've also bypassed the manifold heater and capped off the troublesome bottom outlet of the thermo housing and the rear upper block outlet. Seems to work perfectly so far. I guess it will be different in a pre face.lift car though, but for me it was a straight swap and as I say the two rad elements looked identical side by side.

Must take some pics I guess

[nickphine]

Some pics,

[ezagood]

nice to hear a project car coming to life. i really liked the pull of mine. i thought it made a good car better. have fun with it.

[e301988325i]

Hoses wise, I just used all the standard m20 hoses, the only different thing is that there is no pipe going from the rad into the expansion tank, but this is all internal in the is rad. I've also bypassed the manifold heater and capped off the troublesome bottom outlet of the thermo housing and the rear upper block outlet. Seems to work perfectly so far. I guess it will be different in a pre face.lift car though, but for me it was a straight swap and as I say the two rad elements looked identical side by side.

Must take some pics I guess

Looks really good.

How's your heater matrix being fed if you've blocked the rear outlet of the block?

[JAFF]

great read ! ,im just about to start a build also as a winter project ,how do you tell the differences in the pistons with regard to machining them down ?? also i notice you have a standard airbox ,is this better than a K&N or just personal preference ?i feel i have much reading left to do on this subject iv currently brought or in the process of buying
2.8 crank -brought
vanos seal -brought
m50 130mm con rods -buying
recon 885 head -buying
late m20 -sourcing
2.8 injectors and rail -brought

quite like the idea of the 318is rad !,also thinking about larger inlet manifold ? do you need to uprate the oil pump or water pump etc ???, i need steering in the right direction with everything else

[Simon13]

did the M21 oil pump bolt straight in? No oil leaks yet from the higher pressure anywhere?!

[nickphine]

M21 oil pump looked the same as the old one, bolted up perfectly and thus far no leaks, fingers crossed.

Standard airbox and cam, ecu etc just for cheapness and easy set up and from what i've found so far it's plenty quick enough to be interested. Also keeps it quiet, bit too quiet actually!

The heater pipe is fed from the back of the head, the block one just feeds the throttle body heater, so no probs.

The 2.8 seems easier than the 2.7, not that i've done a 2.7 mind. Knowing how easy it was to set up, I.e. none, I'd be hard pushed to bother with changing any injectors, cams etc as it seems likd it's a lot of hassle. Certainly if money is tight a bog standard top end works really well, I can vouch for that.

Nick.

[JAFF]

im going with the standard head but iv got 2.8 injectors so be intrested to see if ill have to do anything different with the ecu etc

[nickphine]

Car was driven in anger for the first time last.friday. Dare I say it. But my engine is brilliant, shocked! Basically totally standard barring the fact it's a 2.8, faultless fuelling, revs sweetly and is a good chunk faster than a good 2.5, had a direct comparison. I would totally recommend the conversion..

[sweep]

How does it pull nick?

[Kedge]

Sounds good, i'd just be too tempted to play with the head i think.

Not something your thinking of trying at a later date?

[HairyScreech]

i think most people are holding off on paying for head work until me, reggid and a couple of others are done messing about with them.

when we are done i expect a whole new round of 2.8 building to commence.

[e30topless]

interesting how you have done away with the expansion tank, so the pipe on the back of the head feeds the matrix where does the return go to ?

is the motronic running a normal b2.5 chip?

[nickphine]

I fancy building a 3.1 next when the head stuff gets sorted out, but may just be dreaming! But an all steel 3.1 on triple webers gives me the massive horn...

Motronic wise, just bog standard chip. As I say barring the exhaust and possible raised compression due to the deck height being reduced to 205.5mm as per ant's instructions. Standard inlet set up completely right down to the paper air filer (no manifold heater mind), standard but rebuilt head, and btb full single pipe system. It pulls cleanly all the way from tickover to the redline, ticksover nicely etc and is super torquey, doesn't run out puff at the top end etc. I ran out of money, hence the standard top end etc, but I'm glad I did as it's so sweet to drive and as I say faster than good 325 sport (had a dice). It was pulling as well as a 3.2 evo e36 M3 out of the chicanes too, but my car is reasonably light.

Heater pipe wise I just used my standard 318is rad, blocked the back of the block outlet off and ran the matrix return straight back to the bottom of the expansion tank, 318is styley... Had to trim the end of the power steering adjuster bracket off to clear the hose though. That side of things works fine!

[JAFF]

would you mind putting up a brief description for people to follow with regards to the way you have built your 2.8 ,if you are id like to follow the same trend that you have done as its all up and working OK ,
things like decking the block by how much ,and the type of pistons used etc ,
as a building block for us not so mechanically minded of us that want to give it a go

great to here its running smoothly im looking forward to starting mine once iv sprayed the block