E30 Zone

hey guys i wanna do my 2.8l stroker soon but just have two questions. i know there are two types of pistons in m20b25 motors, one has high compression and the other one lower. i believe mine has the 8.8 ratio. will this make a differnce in performance when i build the motor or are they the better pistons to use? and qustion two is i keep hearing people mension different types of m52b28 crankshafts, some are vanos one and two or something. whats that about?

after i sought these facts out i should be ready to start buying parts so any help is much appreciated

ive read that link a while back and there are some good tips. i was just wondering if there are different types of b25 pistons and different m52b25 cranks. like i mentioned i noticed on forums people said there was 2 of each, which should i be buying?

As for pistons IIRC only the crowns differ the early ones are high comp and late are low comp, provided your using the donor M20B25 head and block either piston would be fine.

As stated in another of those links there is are two different M52B28 cranks one Vanos one dual Vanos IIRC, and as from what I've read in those links the later dual vanos is not a direct fit. The single vanos was found in early M52B28 engines and is the one you need.

Aiello wrote:.... and different m52b25 cranks.

B28 cranks right?

Afaik the later twin vanos (M52B28TU) crank won't work as it fouls the piston skirts?

Ant Is the man to talk to.

Andy

Andy325i wrote:

Aiello wrote:.... and different m52b25 cranks.

B28 cranks right?.

I expect that was just a typo.

Andy325i wrote: Afaik the later twin vanos (M52B28TU) crank won't work as it fouls the piston skirts?

Correct.

Andy325i wrote: Ant Is the man to talk to.

Andy

Thats really starting to annoy me. It seems this is the current technical help zone mantra. Ant whilst highly skilled is not the be all and end all of engine tuning, there is no secret to building a 2.8L M20 and its all here on the zone and almost nearly in spoon size portions and step by step photos if you look about a bit.

I doubt Ant would appreciate calls from everyone everywhere expecting technical help over the phone for free, as nice a chap as he is he runs a business and needs to put food on the table.

cool, thanks for the info guys, if i decide to use my m20b23 block and bore it to fit the b25 pistons and head will i run into any probs with the crankshaft.

And sorry to be breaking nuts but any cam shaft reconmendations, i originally wanted a 284 but the guys on e30tech told me it would be to much for a n/a moter and a 273 would be better, any opinions from guys that now what works or not would be appreciated as they seem to do more 2.7l motors and lots of guys do the 2.8l combination i want on this forum.

thanks guys.

march109 wrote:

Andy325i wrote:

Aiello wrote:.... and different m52b25 cranks.

B28 cranks right?.

I expect that was just a typo.

Andy325i wrote: Afaik the later twin vanos (M52B28TU) crank won't work as it fouls the piston skirts?

Correct.

Andy325i wrote: Ant Is the man to talk to.

Andy

Thats really starting to annoy me. It seems this is the current technical help zone mantra. Ant whilst highly skilled is not the be all and end all of engine tuning, there is no secret to building a 2.8L M20 and its all here on the zone and almost nearly in spoon size portions and step by step photos if you look about a bit.

I doubt Ant would appreciate calls from everyone everywhere expecting technical help over the phone for free, as nice a chap as he is he runs a business and needs to put food on the table.

I expect it was a typo too, hence clarifying

I mentioned Ant, as iirc it was one of his posts that mentioned about the issues with the later type cranks.

I appreciate Ant probably doesn't know EVERYTHING about tuning BMW's, although from what I have read, he only gets positive feedback, that says a lot in my eyes. Also if he gets work to put food on the table from this then great.

Furry muff, on all your points, I'm not specifically targeting you with my comments.

BTW there are two people posting today about M20B28 cranks I suspect this guy is too far away to post to but why don't you post on the other thread and you might sell it, it is a very good price 50% of what I paid.

Aiello wrote:cool, thanks for the info guys, if i decide to use my m20b23 block and bore it to fit the b25 pistons and head will i run into any probs with the crankshaft.

And sorry to be breaking nuts but any cam shaft reconmendations, i originally wanted a 284 but the guys on e30tech told me it would be to much for a n/a moter and a 273 would be better, any opinions from guys that now what works or not would be appreciated as they seem to do more 2.7l motors and lots of guys do the 2.8l combination i want on this forum.

thanks guys.

???, dont mean to sound like a twat but is there naybody who could answer my last post

get a 273 a 2.8 wont really like a 284 cam due to it being a more high reving cam when a 2.8 is ment to have lots of torque.

TBH I don't know if the 323 blocks are the same as other M20 blocks!

284 is probably too lairy for a car where all the torque os waaay low down the rev range. But I have no experience of this either, personally I am going for a stock 325 cam with my 2.9L.

I have experience of a 273 in a 2.8 and it goes some, I'd go with that

alpina used a 264....I think they might know what they are doing

If you stick to motronic then Ant sells a chip that drops into the ECU for the 2.8. I'm using it at the moment very successfully. Would have like to have gone for Megasquirt to set it perfectly and drop the barn door, but I needed to do some more work on the car which ate up the budget, doh.

My photo's start to finish are here: http://www.msportster.co.uk/detail.asp?cat=22

To get my crank I bought a full bottom end from a breaker (try www.partsgateway.co.uk), it only cost around £100.

Base engine was the later model M20B25. I'm using a dbilas 282°/272° cam, its got just under 1000 miles on it and going well

For cams it depends what type of torque curve you want, a schrick 284/272 for lowend and midrange torque (i've seen 87% peak tq at 2000rpm on a 2.8 M20, 90% on a 2.7, 80% on 2.5L), catcam 273 for a bit more topend but a bit less on the bottom (oz's 73% peak tq at 2000rpm) and 283 catcam for even more uptop and even less on the bottom

cool guys, thanks for the advice, i think id like the 284/272, im not worried about the aggresive idle but that 273 is always keeping interest aswell, i guess since i want most of my power in the mid to top range the 273 is more practicle, i like to drag so the power counts when the revs are high and a 4.1 diff should make up for slight lack in low rpm performace.

no i dont need a chip by the way, ive wired up a standalone microtech computer in my car which runs her just fine. never heard of megasquirt in australia other then on e30 forums and was wondering if they are a good computer, i tend to steer away from the brands that i dont know. but on the plus side if anybody needs advice to wire a microtech just throw a question my way and i might be able to help

guess i go shopping for my crank soon. since i will be rebuilding the bottom end is there anything i can do to improve performace further, i know lightening the crankshaft and flywheel helps. anything else or is all that just a waste of cash $$$? im really only interested in combination that work as i dont exactly have cash over flowing out my wallet, im just a bored apprenice mechanic with a spare engine and a e30, lol