2.7 ETA crank and rods into a m20b25

[Sammy J 1]

Hey all,

i was wondering, can you just put the 2.7 eta crank and rods into the m20b25 block and use the 2.5 head etc beacuse you use the 2.5 head and manifolds on the 2.7 eta block . Does it matter if you do it this way or do you have to use the eta block with the 2.5 head etc? How big of a job is it, is there much work involved? I can get most things done myself except for machining. Any help would be much appreciated

cheers

[Mike 1]

cheapest/easiest way is to use a late model 323i head and chuck that on the 2.7 crank/rods/pistons as that way the pistons will match the combustion chamber.

Most other combos involve mucking round deck heights and adjustable sprockets, or custom pistons. otherwise your left with low compression, which is only really good for turbo.

If it were me I'd do the 2.7 block with B23 head but use the later 325i motronic management with a 2.7 chip.

have a search on here, or e30tech and r3v, soooooo much info out there.

Edited June 12, 2008 by Mike

[Sammy J 1]

i did some searching earlier today and found a site which is quite detailed about doing it, is this a good way to go or not so much. When you say a later model 323i head, how later model? id be using my injection and engine managment with bigger injectors and would look at a chip. here is the website its quite a good read

http://www.strictlyeta.net/technical/328i_2.html

[Mike 1]

From memory the late 84 to 85 323's had the big port heads. after that they stopped 323i and went to 325's.

bigger injectors wont get you any more power unless your leaning out the stock ones, but looks like stock is around 150cc/min, not giving much more than 180hp. so depending how your build go's they probably will need replacing.

EDIT - injectors smaller than I thought

Edited June 12, 2008 by Mike

[Sammy J 1]

to find out how much an injector can handle you take its flow rate and divide it by 5, then times it by how ever many injectors in this case 6 and you have your hp rating assuming the injectors are running 100% no build up or anything. its a rough way to do it.

[Jeddy 0]

to find out how much an injector can handle you take its flow rate and divide it by 5, then times it by how ever many injectors in this case 6 and you have your hp rating assuming the injectors are running 100% no build up or anything. its a rough way to do it.

Stock ones are good for around 220-250hp so unless your ones are screwed don't worry about changing them.

Chucking the crank and rods in can and has been done but i think the block needs to be decked and maybe a different pulley??? Heaps about this as mentioned on e30zone and e30tech, have a search there.

Other way is 2.7 Block, 731 Head but as you've already got a 2.5 probably not worth it.

Good luck finding a 524d crank in NZ though.

Let us know how it goes

[Mike 1]

^ see edited post above:

I highly doubt that stock will do 250hp, especially on a motor thats only 170hp standard. 180hp is pushing it if they are only 150cc/min. can someone confirm the stock size on a M20B25?

no need for a 324d crank either? 525e does just fine.

thinking about it you could always just put your 325i head on that 2.7 block with the 2.7 pistons and rods. Couple of different thoughts on the exact c/r going round, would be interesting to see what the full storey is and how well it goes even with the lower c/r.

Edited June 12, 2008 by Mike

[Sammy J 1]

apparintly its only about 8.something:1 with the 2.7 pistons because they dont match the head. your right about the injectors they lean out at about 180hp

[beemwr 46]

apparintly its only about 8.something:1 with the 2.7 pistons because they dont match the head. your right about the injectors they lean out at about 180hp

Yeah, picked up a 324d engine a couple of months for steel crank to use in a 2.7 screamer. The 525e crank doesn't want to go past 6000rpm.

another budget consideration is to use a 323i camshaft over the std 325i, forgotten exactly think nearly 260- degree as opposed to ?250-degree 325i, acheap mod if you already have an engine to pluck conrods from pluck the camshaft too.

Andrew Everett's (An Editor TBMW) BMW e30-3 Series Restoration BiBle is a great resource for all budding e30 owners and has a bit to say about 2.7 upgrades.

[martyyn 2]

Hi David,

How is your 2.7 'screamer' going ?

Cheers

Martyn

[beemwr 46]

Hi David,

How is your 2.7 'screamer' going ?

Cheers

Martyn

Hi Martyn

At the moment down-sizing number of vehicles , moving house and chasing second hand internals for an F3-201 Hewland gearbox project. Got most of the parts for the 2.7 screamer just some time and money needed to progress.

probably will end up next years resolution.

Cheers

Davidp