212 bhp M20

[Whitty]

Hi all, You can build a 2.8 litre m20 with less work than a 2.7.I haven't done it but Andrew Everett describes the process in his book the" E30 restoration bible" on pages 135 and 136.The end result ,an engine that has produced 212 bhp and 210 lb/ft torque at 3500 rpm on the dyno and with a 3.91:1 lsd it would break traction in the first three gears and rev to around 6000 rpm . .The basis of this engine is the 2.8 litre crank from the alloy M52.He says there is a reasonable availability of them due to the Nikasil problem and has never paid more than 50 pounds for one.The reason I think it is easier in theory than the 2.7 is there is no need to have the block skimmed 2 mm and therefore thevalve timing will not need to be adjusted.Due to the 84 mm stroke ,the piston will now protrude from the block 0.4 mm and a thicker head gasket will comfortably take care of this.This engine has 9.6:1 compression,runs on 95 octane, standard exhaust, standard 325i head,standard BMW valve springs ,used injectors from a 530i M30 , standard 325i airflow meter and throttle body and a remapped ECU.
Can anyone try to source these cranks ?Could these then be sold through this site?I've been unable to find any here in Sydney............Richard

[Jon_Bmw]

Hmm i don't like the sound of a thicker head gasket, because if the head is already skimmed, you're asking for blown head gaskets at every turn.
I think the AFM will start to become a restriction also, an m30/m20 hybrid would be better and a standalone...even better.

Sounds like an interesting project, there are several people on here with 2.8's but i don't know how they have done it, all different to some degree i'm sure.

I think to get to that claimed figure you would need to be drop kicking the AFM, have a six branch and possibly some other trick bits.

Just adding a crank sounds all to easy imo.

[stevetigger]

yes what Jon said, if it was just as easy as dropping in a crank....we would all have 2.8's

[buster]

Adam has a 2.8 engine which was built by andy everett.
Bloody hell he's wrote a book
Oh well fair play to him,hope he makes millions !!

[buster]

heres the info you want :

Block is 325i or 525e. Crank is from M52 2.8 (328i, 528i and 728i). Con rods 130 mm from M20 320i, 520i, 323i, 525e. Pistons 325i with 14 mm shaved from skirt to clear crank. This combo works perfectly, no machining of pistons or block is needed.
Crank fits block perfectly without any modifications. All that needed doing is a sleeve machining - use the centre part of the crank front pulley for this. This then replicates the stepped part of the M20 crank where the front oil seal sits. The conical thrust washer needs slimming down by 2mm and the shank of the front pulley bolt needs about 15 - 20 mm taking off. This allows the threads on the bolt to reach further up into the crank. The threads in the M50/52 crank are further up the nose of the crank than the M20.
Also fit the M20 spigot bearing.
And that's it. I'm sure others will reinvent this idea and claim it their own.........

The Yank conversions use a specially made crank and rods which seems like a lot of effort for bugger all gain over what I did to be frank.

The question you're going to ask is....can a 3 litre M52 crank be used? The answer is no. The stroke is too long. The 3 litre M3 crank also. The length of the con rod must NEVER be shorter than the crank stroke x 1.5. Thus a 525e (81mm) works out at 121mm with a rod length of 130 mm. The 2.8 I built has an 84 mm stroke (equalling 126 mm - still okay with 130 mm rods).
The 3 litre M3 crank is 85.8 working out at 128.7 - getting a bit too close and you find a spare M3 crank. The 330Ci crank is a whopping 89.6 which is 134.4 so useless. Even with 135 mm 325i rods it wouldn't be very nice. 3.2 M3? 91 mm stroke thus 136.5 and no good.

How did BMW get around this? They made the M50/M52 (1990 onwards 24v) block much taller. As a result the 2 litre conrods in the 1990cc M50/52 are about 140 mm long.

No probs mate. Because you're using stock 325i pistons which come to the top of the bore, it'll give 325i compression. The motor Adam has used early (chrome bumper, non catalyst) pistons which have a 9.7:1 compression. These pistons also had a skirt which was about 10 mm longer than the later ones (i.e plastic bumper) so obviously you've only got to take 4 mm from later ones.
That's why when building a 2.7 using Eta bits, you can 99 times out 100 put the later pistons straight in. I would use early pistons because the compression is much higher - later ones are 8.8:1 which is why the plastic bumper 325i doesn't quite have the bite of the older ones.

The problem with the 2.8 is finding a crank. The machining bit is a piece of piss to a machione shop - just give them the 2.8 crank plus the pulley centre plus an old M20 crank and it's really obvious what needs to be done.
I wouldn't say it's hugely better than a 2.7 but 100cc is 100cc at the end of the day and cubes mean horses!
I'd imagine the car feels undergeared now with that 3.91 diff as well - maybe a 3.7?

[Andy325i]

Very interesting

Andy

[Jon_Bmw]

Hmmm interesting stuff buster, so a fair bit of machining and general buggering about is required to do it, not just whip the crank in and out. As you say s50/s52 engine just seems like the obvious answer, more power, throttle bodies/quicker response if you are going to the effort of all the to get to 2.8.

You say 3.0litre isn't achieveable, i'm sure there is a guy on e30tech who is doing a 3.0 stroker m20 with a turbo...yes i know they are mental over there. This is possibly with custom pistons and rods, i shall have to research this more.

Back on topic even if you got to that 2.8l capacity i still think you would need to bin the AFM and use a 6 branch to even get close to 210bhp claimed in that book...someone prove me wrong and get a mint engine out of the argument.

[A1BMW325iSport]

this is very interesting, thanks for info

[buster]

I got it from adam.

[Jordan]

Hmm i don't like the sound of a thicker head gasket, because if the head is already skimmed, you're asking for blown head gaskets at every turn.

You realize the thicker head gasket is a OEM item right? Its 0.3mm thicker then the standard one. It allows for retention of stock compression after decking a head to straighten it etc.

Absolutely nothing wrong with it. It's made of the same exactly materials as the thinner one, but the same exact makers. It squishes in the same manner as well.

[Euro3]

Sorry to Jack your thread for just a sec.
Wow Jordon did they kick off the US forums...........JK
Since you work for Terry how much should I ask for this stuff.
Things that are included are
Engine, all accessories. 130k
5sp
exhaust
wiring harness includes key and ignition, the cluster, the trip computer.
ecu
gas tank.
Thanks,
Kevin

[Jordan]

Sorry to Jack your thread for just a sec.
Wow Jordon did they kick off the US forums...........JK
Since you work for Terry how much should I ask for this stuff.
Things that are included are
Engine, all accessories. 130k
5sp
exhaust
wiring harness includes key and ignition, the cluster, the trip computer.
ecu
gas tank.
Thanks,
Kevin

I think all of this is really Off Topic in this thread.

Also I have no idea what car/engine/ who knows what all that is from.

[Euro3]

Jordon sorry real quick E36 M50

[Jordan]

Worth about $1200-1500 USD to the right person as a package deal maybe.

[Euro3]

OK thanks man, again sorry to Jack the thread.
Kevin

[Jon_Bmw]

Hmm i don't like the sound of a thicker head gasket, because if the head is already skimmed, you're asking for blown head gaskets at every turn.

You realize the thicker head gasket is a OEM item right? Its 0.3mm thicker then the standard one. It allows for retention of stock compression after decking a head to straighten it etc.

Absolutely nothing wrong with it. It's made of the same exactly materials as the thinner one, but the same exact makers. It squishes in the same manner as well.

Well you are obviously more qualified to say(being 2., but the chances on a more general aspect are that a thicker head gasket will blow first, right?

As you said with this possible project i suppose you are right as long as its OEM gasket, may possibly want to use head studs just to be on the safe side. What do you make of the gaskets TDC(i think that is his name on e30tech) sells, copper springs to mind.

I'm sure you'll answer in about 8 hours time.

[Motorhole]

Instead of a thicker head gasket, could you not skim some metal off the top of the pistons??

I know Ireland Engineering do a kit for a 3.0 stroker, but its not cheap!

I fancy having a go at this 2.8i conversion once I get another E30, as I reckon it could be done pretty cheaply in the garden shed you know

If I decide to go ahead with it, I will let you know, but I won't have another E30 for a couple of months yet

[Morat]

Sounds like an excellent basis for a kit for the more cack-handed members of the E30 community.

err, that'd be me then.... ;)