Mounting a e12 head with flat top pistons m10b20

[Tjurd]

I have a m10b20 with flat top pistons wich originally came with a cilinder head with the inscription e21 2.0
The cilinder head has cracks so i need a new one.

I have done some research and found out that ther are 4 type's of cilinder heads for the 2 litre engines; (for all bmw's)

- 121/121ti head: 58cc, 1972 and earlier

- e12 head: 61cc, 1973 to 1975

- e21 2.0 head: 60cc, 2002 and 320i, 1976 to 1979 ( i think the original Cr is 8.1:1 )

The e12 head comes with high compression pistons (i think piano tops) and these pistons can only fit with the e12 head.

I have got the flat top pistons wich come with the e21 2.0 head.
According to my research the e12 head will fit my engine

My Question is:

What will happen if i mount the e12 head on my m10b20 with flat top pistons.
wil my compression ratio drop drastically?
Wil the engine have power'?

p.s. The eingine wil not make use of a turbo and wil be stock with a carburettor driving on lpg and gasoline.

[nas80]

you will lose compression - but why not replace it with a 1.8 m10 head and work the head so that you can use the bigger valves from the 2.0?

[Tjurd]

Thanks for your repy,

ive got a good 1.8 carb head lying around but i couldn't find the cc's of the head so im not sure what it will do.
and i dont have the means to mesure the cc's.

Ive read stories of people putting a 1.8i head on the m10b20, but they got lower compression so it would be ideal for a turbo set up.

Not sure what the carb 1.8 head would do, ive compared the cambers and they look quite the same, though the pistons have a piano top but dont have the same stroke though.
Has anybody here got any experience fitting a carbed 1.8 head on a m10b20?

[misza]

maybe this will help

[PeteK]

If you can't get anything else and you need it to go urgently, I'd go with the e12 since it'll work, just not as well.

If you had the time and/or money, I'd go with a modified 1.8i head. That's what I'm going with.

Cheers

[Tjurd]

Thanks for the replys guys,

Thankfully i found a next e21 2.0 head, so i can keep everything nice and orginal
this weekend its off to the specialised company that wil fix the head up for me.
hopefully no cracks and or corrosion like my previous two e21 2.0 heads