2.7 Rebuild info

[Jordan]

You are going to need to bore the block out to 85mm to make a 2.8L

[Gus]

sorry i would have mentioned it, but thought it was obvious. im just throwing ideas around and trying to find more info as in NZ not many strokers are around that have been build recently (ie people knowing what goes into them). may just stick with 2.5 for the project and do something to get more power later.

[chuck90m3]

Also, food for thought.

S54B32: (8,000 rpm limiter)

Stroke 91 mm
Rod length 139mm

Rod ratio 1.53

so with the E46 M3 crank what rods and pistons do you need?
im new to the M20 game so im just looking at my options.
i have a 91 325i and i also have a full 88 528e engine.
what combo would work the best(crank,rods,pistons) with out major machine work, and what would be the CR of the chosen setup?

thanks in advance for the help.

[JJGBMW323]

You are going to need to bore the block out to 85mm to make a 2.8L

Correct. My stroker 1989 325i block is a 2.8 liter using Metric Mechanic pistons and its been bored out to 85 mm. The previous owner used the "I" rods and the eta crank. The eta crank is 81 mm. I am replacing the eta
crank with a knife edged 524td crank.

I have since sourced an 95 m3 s50 crank. So some day I am going to use
the s50 rods with this to build even a bigger stroker. But for the time being
I want to run the 2.8 M20.

Head 1990 325i ported and polished - +1 valves
-325i cam reground to 272

Block 1989 325i 2.5 liter bored 85mm - forged MM "I" pistons

Crank 1986 524 td -Knife edged 524 td crank.

Flywheel -11 pounds lightened 325i flyweel.
Oil pump -524td oil pump.

[madjurgen]

Whats the reasonable limit for boring? 85mm? 86mm?

Does the m52b28 crank drop right in like the s50 or eta one?

[gstuning]

There are two simple ways of doing a 2.7i

First and cheaper and simpler,
84mm block
Eta crank
rods
pistons
731 head (323i/320i)
325i fuel injection and exhaust

Second,
84mm block
eta crank
I or eta rods
customs pistons with compression of choice to suit the rods picked
887 (325i) head
325i fuel injection.

If you have a ETA engine, get a 325i fuel injection and a 731 head and your done.

If you have a 325i engine , get custom pistons and your done,

Those are the choices.
2.7 with 731head is ideal for those with ETA motors,

731 head are EXTREMELY comon in europe , they have double valve springs, high cam and 1mm smaller valves then 325i heads, but they do have a better squish zone so potentially equal when looking for about 190-200hp out of your eta.

If you live in europe, get a eta engine and a 320i engine, 325i FPR and 325i injectors, and your done, all can be had for small amounts,

I fail to see why strokers are complicated

[SpecM]

I fail to see why strokers are complicated

-Cuz you don't live in America. We don't get a 731 head and our people are too cheap for custom pistons.

[gstuning]

731 heads aren´t exactly exspensive you know,
it only takes registering on the e30zone.co.uk forum til get one.

[silversleeper]

so, with my us 325i, i can just slap a nice set of high cr forged pistons and call it a day?

[SpecM]

so, with my us 325i, i can just slap a nice set of high cr forged pistons and call it a day?

-Of course. But then, you wouldn't have a stroker.