M20B25 rebuild suggestions

[Synysterkyle]

Hi all, I've just got a spare m20 engine from an automatic, it's done around 90k I believe. The plan is to whack it on a stand and slowly rebuild it, get the bits powdercoated etc.

First off will this engine fit in my manual m20b25 ? They're both chromies.

Another thing, is there anything worth uprating/modifying while it's in pieces ?. I read something about shaving the piston rods down to save weight. Is there any little things like that I could do ?. I'd love to turbo it if I come across a bargain but that might have to wait.

It's going to be the first engine I've had completely in bits so should be a learning curve !

Any advice is appreciated, cheers

[HairyScreech]

yep, should fit no trouble but may need a new pilot bearing in the fly wheel.

[Speedtouch]

As above, spigot bearing at end of crankshaft may be different.

It may be worth converting to later Motronic 1.3, as the early chromey 325i had Motronic 1.1 which has a flywheel sensor. The little metal peg tends to fall out of the flywheel, then it won't start, and it's an engine/gearbox-out job to replace!

Motronic 1.3 is more reliable, gives better driveability and easier to chip.

[Synysterkyle]

Great thought might be the case !

I'll have to have a read up on the motronic 1.3, I'm guessing it's a case of swapping the loom and ecu ?.

[Speedtouch]

Yes, I believe that is the case - do a search on here, as some people have done this conversion.

Here's one example:
http://www.e30zone.net/modules.php?name ... 78&start=0

Or you could do a Megasquirt conversion - see the Zone Wiki for a guide.

[Eddie25]

Cam and 6 branch

Really makes an M20 come alive.

[Synysterkyle]

Yes, I believe that is the case - do a search on here, as some people have done this conversion.

Here's one example:
http://www.e30zone.net/modules.php?name ... 78&start=0

Or you could do a Megasquirt conversion - see the Zone Wiki for a guide.

Mines an 86' so i'm guessing its the Motronic ML1.0 ? from what I can tell from the wiki.
Looks like i'll need all the bits, CKP sensor, Oil level sender, ecu etc.

Megasquirt is quite pricey though isn't it ? Probably be cheaper picking up the loom etc from a car being broken

Cam and 6 branch

Really makes an M20 come alive.

My car has a chip at the minute apparently and was told a bigger bore TB and 6 branch would push it to 200bhp according to the previous owner anyway. Any suggestions on a 6 branch ? and i'm guessing the cam would be an aftermarket one ?

[Speedtouch]

Yes, yours is probably ML1.0 or M1.1 - M1.3 came in with the mid-1988 (E/F-reg onwards).

Megasquirt can be built quite cheaply if you're handy with a soldering iron; see Flappysocks' site www.diyefi.co.uk

You'll struggle to get an M20B25 to crack the 200bhp barrier - most 2.7s don't quite make that.

The BTB is the best six-branch, but they are expensive. A Hot-tuning one for £200 is OK, but don't expect much gain.

[Synysterkyle]

I'll have to find out prices for the megasquirt, i've always liked the idea of it, was planning on having it in my old golf but never went big turbo in the end.

When people mention cams, are they lightened aftermarket ones or just standards skimmed down ?

Don't suppose there are any guides or threads on completely overhauling the m20 ?

[Andyboy]

Forget mega squirt, more aggro than it's worth. Moronic 1.3 properly mapped is just fine.

[Synysterkyle]

Someone on here has advertised all the bits for the motronic 1.3 conversion so im going to go for that, saves me sourcing all the bits seperatly !

[Speedtouch]

Good move - a very worthwhile conversion. PM sent.

[Synysterkyle]

Found a handy link for rebuild parts

http://e30performance.info/viewtopic.php?f=21&t=269

Engine stand arrived today so should be making a start on this soon !