2.7 or 2.8? whats the diff....

[luvin my 325es]

Difference? Crank, pistons?
I want to use a donor 87 325is to stroke my 86 235es.
I read about using a crank from 524i? TD, eta block, rods.
Top half , from pistons , head, intake, ecu would be from donor is.
Would that be a 2.8 stroker?

[rs4pro3]

that would be a 2.7, to get 2.8 you have to bore the block and install larger diameter pistons.

[SA E30]

U could either bore the block.

Or use a longer stroke crank

84mm piston and 81mm crank = 2693.3cc
85mm piston and 81mm crank = 2757.8cc
86mm piston and 81mm crank = 2823.1cc

84mm piston and 84mm crank = 2793.1cc
85mm piston and 84mm crank = 2860.0cc
86mm piston and 84mm crank = 2927.7cc

84mm piston and 86mm crank = 2859.9cc
85mm piston and 86mm crank = 2928.1cc
86mm piston and 86mm crank = 2997.4cc

These r just a few examples... off the top of my head using BMW cranks (324td / eta , M52B28 , S50B30 ) and std piston, oversize, and my fav 86mm piston ;)

Just to show u that u can get a 2.7lt or 2.8lt from a no of combinations.

[Sean]

He could also use an S52 crank, 89.6mm - that would get you damn close to 3.2i with the 86mm pistons. :D This required some modification within the block though.

[luvin my 325es]

So basically I need to bore my eta block, get new pistons, use eta crank, rods and I will be close to 3.0L?
I am wanting 225-250HP at the crank N/A. Somthing comparable to http://www.metricmechanic.com/ sport 3200 230HP which they sell for $8295. Is this possible or will I end up spending more on headwork, cam, maf, chip etc?

[nando]

I would have loved to go with the MM 3000 kit, 84mm M52b28 crank, 138mm rods, and 86mm pistons. but I'm pretty happy with my 2900 (81mm stroke, 86mm bore).

[Eric]

i'm pretty new to the M20... what crank gives the 86mm stroke?

[Sean]

i'm pretty new to the M20... what crank gives the 86mm stroke?

86mm stroke is the S50 crank.

89.6mm stroke is the S52 crank.

[digger]

86mm stroke is the S50 crank.

89.6mm stroke is the S52 crank.

Is the stroke 86mm or 85.8mm? MM say 86 but i'm sure i have seen elsewhere 85.8 somewhere or are there two version of the 3.0L US m3

[Sean]

Is the stroke 86mm or 85.8mm? MM say 86 but i'm sure i have seen elsewhere 85.8 somewhere or are there two version of the 3.0L US m3

I thought it was 86 - but I really wouldn't know for sure.

[SA E30]

I know the Euro S50B30 is 86mm

138mm rods ... how long that been around ? When I built my 1st stoker everybody told me I was daft 2 use them... BTW, this is on a 84mm M52B28 crank.

135mm rods = 1.607
138mm rods = 1.642

So IMO 135mm rods give a better rod ratio on a 84mm throw crank.

A mate of mine has a M54B30 crank in his M20 ... Dunno what was done 2 get that in there.