85mm pistons?

[87mtech27]

is there any bmw model which came with 85mm pistons which could be used on a e30 m20

[DanThe]

I think one of the M40 variants used 85mm

[appletree]

Think the M42 has 84mm pistons but dont quote me.

Think neil 320? tryed some as i bought a m42 head off him after he bought the engine to try the pistons

[DanThe]

Didnt they use 85mm pistons to get 1.9 litres for the E36 things?

[87mtech27]

just to confirm, will a 85mm piston slip into the standard 325i block without any modification

[e21Jason]

No

You need to bore the block

Jason

[maggspower]

No

You need to bore the block

Jason

Thats right, m20b25 is 84mm bore.

[87mtech27]

No

You need to bore the block

Jason

Thats right, m20b25 is 84mm bore.

thankz

does anyone know what mods alpina did to the 323i based c2 2.5 to get a displacement of 2556cc

[reggid]

I belive they did 323i 76.8mm crank, 84mm bore

[odbod]

The 85mm pistons are indeed from the 1.9 M44 engine. Used in late (96/97 onwards) E36 318is 318ti compact and Z3 1.9

[87mtech27]

sorry sound a bit silly asking this but what is the size of a (m20) 325i crank and a 325e crank

[87mtech27]

also will the standard gasket set work with a 85mm bore

[maggspower]

These are not silly questions, silly would be buying all the parts then finding they dont fit

The throw of the 325i crank is 75mm, where as the Eta crank is 81mm.

Not sure about the HG, you would have to offer it up to the block to see how mich you have to play with. Some people on here have had HG made by the likes of Ferriday engineering, but that will cost a few £££

[DanThe]

Use the search, 90% of what you have asked has been covered before, im sure google would answer most

[87mtech27]

Use the search, 90% of what you have asked has been covered before, im sure google would answer most

i cant seem to find much on 85mm bore m20s or the head gasket.

[DanThe]

Here is some good info

http://www.strictlyeta.net/technical/328i_3.html

http://forums.eurocca.net/showthread.ph ... 68&t=31632

http://www.vacmotorsports.com/catalog/e ... 051-cr.htm

[87mtech27]

Here is some good info

http://www.strictlyeta.net/technical/328i_3.html

http://forums.eurocca.net/showthread.ph ... 68&t=31632

http://www.vacmotorsports.com/catalog/e ... 051-cr.htm

thankz

[goosiegander]

Are there not special oversize pistons for the b25? I thought looking at the bently manual there were 3 different diameter pistons available...

[87mtech27]

Are there not special oversize pistons for the b25? I thought looking at the bently manual there were 3 different diameter pistons available...

i thought your could go overbore aswell (upto 86mm iirc)

[reggid]

Use the search, 90% of what you have asked has been covered before, im sure google would answer most

i cant seem to find much on 85mm bore m20s or the head gasket.

i use 86mm pistons on stock headgasket though pistons have a chamfer

[kimbo]

85mm is the 2nd overbore from standard and would therefore be available from more or less anywhere. Guess std replacement head gasket would work.
Dont forget that pistons from M44 etc will have four valve pockets and will thus probably foul with the 2 valve head.

Kim

[Simon13]

Are there not special oversize pistons for the b25? I thought looking at the bently manual there were 3 different diameter pistons available...

only standard oversize for rebuilds when the bores are shagged

Alpina have kept their formula a good secret no one has stripped one of these engines down to see exactly whats been done

[goosiegander]

Are there not special oversize pistons for the b25? I thought looking at the bently manual there were 3 different diameter pistons available...

only standard oversize for rebuilds when the bores are shagged

Alpina have kept their formula a good secret no one has stripped one of these engines down to see exactly whats been done

Ever in zone history? Shocking...