strange pistons found in M20b23

[BavarianBimmer]

can somebody clarify these pistons ?
Those are not stock I think




A.C.

[Boots Walker]

definitely not stock

alpina perhaps?, i believe they modified the combustion chambers/pistons

[BavarianBimmer]

Alpina is possible

But can you use this bottom-end with an stock head ?
or is it worthless ?

[Jordan]

Don't know what those are, but the valve reliefs are overly huge.

[roadrage]

wow, that dome comes way into the head from the looks of that pic. Ive never seen a stock m20 and I know they are supposed to have fairly high compression, but that looks like a huge CR piston.

[e30Matt]

wow, that dome comes way into the head from the looks of that pic. Ive never seen a stock m20 and I know they are supposed to have fairly high compression, but that looks like a huge CR piston.

Stock M20s have incredibly LOW compression (8.5:1)... probably why those pistons are in there.

[modifiede30]

Don't know what those are, but the valve reliefs are overly huge.

Definitely larger than stock. I'd suggest you find the head to see what was done to it. Might be better to just rebuild with the existing components rather than drop a stock 325 head on it.

[bkelsey86]

323i"s are stock 9.8:1 compression ratio....the stock pistons only have one small relief on the drivers side for the valves.

[modifiede30]

Let me know if you'd have any interest in selling those pistons and rods.

[rs4pro3]

The set of 323i pistons I had were domed just like that, but didn't have the huge valve reliefs, there domed just like the pre 5/85 525e 11:1 cr ratio eta eurp pistons just smaller diameter and won't fit in the 2.5/2.7 blocks