are identical?? or the position of the "perno" is higher on 320's ??????

are identical?? or the position of the "perno" is higher on 320's ??????

The 320/6 and the 323i..are both baby six early m20s but for some reason I thought that the engines and pistons where different.

Some info I found

M20 engine info
The M20 is a watercooled in-line six cylinder engine, with a cast iron block and light alloy head. There are two valves per cylinder, operated by a single central overhead camshaft which is belt-driven. Pistons have three rings, two for compression and one for oil control. The 320/6 and 323i have identical block and head, they are interchangeable. So are the conrods, but the pistons and crankshaft are different.

Looked in the BMW workshop manual and it shows the pistons as being different. 320 pistons have a crown and are marked 2.0/9.2 on top. 323 pistons are flat and are marked 2.3/9.5 on top

hmm ask Stuck this...

It would make sense that the 323i and the 320i have different pistons. The 320/6 is a 2litre 6 cylinder while the 323i is a 2.3 litre. If I'm correct, the added volume of the 323i could be cause by different pistons if the block and head are the same.

It would make sense that the 323i and the 320i have different pistons. The 320/6 is a 2litre 6 cylinder while the 323i is a 2.3 litre. If I'm correct, the added volume of the 323i could be cause by different pistons if the block and head are the same.

I thought that they are different pistons based upon the displacement,
but no matter, the best way to hot rod this is to slap a 2.7 eta under the head.

Anytime the stroke is different, in like engines, the pin height is different.
i.e. the location of the wrist pin on the piston.... the distance from the centerline of the wrist pin to the piston crown.

Then there is the shape of the piston top that can change from combustion chamber design...Like the M10 with 4 or 5 different combustion chambers used over the years, (maybe more than that!!)

Hope that sheds some light.
Jeff

the compression height is vastly different like said above, thats the problem.

320i and 323i's used the same combustion chamber, hell the same head, so there isnt a lot of difference in the pistons.