m20b25 with m20b23 crank?Resulting a 2,3?

[-Jelko-]

Well as i heard using crank of b23 in b25 would result in 2,6 displacement,well the thing is i can probably get b23 crank for dirt cheap(if not free?) and finding eta is hard as shit.Since i like to experiment this is also nice lil project since i got b25 in parts ready to be rebuilt.Can anyone confirm this info to me?


EDIT:wrong title...resulting in 2,6? :P

[-Jelko-]

der bump

[SpecM]

not so sure about this dude, we didn't get 2.3s in America...

what is the stroke of an m20b23?

[M-technik-3]

What rods are you planning to use?

[eta]

A 2.3 cracnk (76.5mm stroke) in a B25 block would require custom pistons as the stock 325i pistons would be 1.5 mm to high. If you shave the 325i pistons you will remove the meant to be threr pertrusions which aid squish.

Also the displacement would be 2554cc as used in the Alpina C1 2.5. Its all be done before.

[E30_fiend]

So really if one purchased custom pistons to match the i rods, would this still be atainable?

[-Jelko-]

A 2.3 cracnk (76.5mm stroke) in a B25 block would require custom pistons as the stock 325i pistons would be 1.5 mm to high. If you shave the 325i pistons you will remove the meant to be threr pertrusions which aid squish.

Also the displacement would be 2554cc as used in the Alpina C1 2.5. Its all be done before.

Thanks dude,that was answer i was searching for!

[SpecM]

huh, with that stroke (76.5mm) an m20b23 must have a very small bore...

[Stu]

320/323 were based on 80mm bore. In the mid-80's, hot M20's were overbore 84.4 on 76.8 (323i crank) @ 2580cc. 210+hp M20's were not uncommon in '83-'84, even with U.S. 93 octane.

[Holland]

320/323 were based on 80mm bore. In the mid-80's, hot M20's were overbore 84.4 on 76.8 (323i crank) @ 2580cc. 210+hp M20's were not uncommon in '83-'84, even with U.S. 93 octane.

If this is true then wtf are we so concerned with 2.7 strokers?

[digger]

If this is true then wtf are we so concerned with 2.7 strokers?

because a 2.7 has more power and torque potential when done properly and the 81mm cranks are more common

[eta]

And C1 2.5 did not have 210+hp. Only the 2.7i C2 had that.

[Stu]

If this is true then wtf are we so concerned with 2.7 strokers?

I meant that there were options utilizing short-stroke engine parts to make fairly substantial power, before the 325i was introduced. Surely an 81mm stroke will make more power yet.