E pistons on I rods?

[itsbrokeagain]

So after rummaging through some old threads, I had found the one containing the specs for all the compression ratios. I found the part number for the M20B27 (83-85 model) which is listed in the program as high compression.

Since they come out of an E engine, is there a difference in the rods between the E and I M20s? I can get my hands on the pistons quite easily and cheap, but I would like to know before I place such an order.

[Aptyp]

b27 rods are 130mm long
b25 rods are 135mm long

Deck Height is the same at 206mm. Now calculate your pin height and see if they'll fit.

[whodwho]

b27 rods are 140mm long
b25 rods are 135mm long

Deck Height is the same at 206mm. Now calculate your pin height and see if they'll fit.

b27 is 130

[Aptyp]

Oops, that was a typo, lol E rods are 130mm


Pin height on E is 35mm and I it's 33. E Piston are taller.

[whodwho]

Oops, that was a typo, lol E rods are 130mm


Pin height on E is 35mm and I it's 33. E Piston are taller.

Not to get all technical on ya...;)

E is 35.7 and I is 34.2

Here is a good source of dimensions for m20 pistons:

http://www.bmwccn.no/rogaland/Mahle_m20.html

[itsbrokeagain]

Hrm that's a real tight setup.

If the cranks are exactly the same, then its no go. I rods would push it up 5mm more, but the wristpin height would bring it back down less that 1mm. That's valve territory lol. Now if I swung e rods as well...

Hrm I got some math to do...

[Brian D]

I stroke is 75mm. e stroke is 81mm. You sure the early e pistons are high compression? Every one I've seen has been a flat top.

[itsbrokeagain]

I stroke is 75mm. e stroke is 81mm. You sure the early e pistons are high compression? Every one I've seen has been a flat top.

apparently it says that the 83-85 euro E engines had 11:1 compression.

I consulted my friend at hte dealership and we poured through the part numbers and he has a listing for them..

[nando]

they are 11:1 CR in the 200/731 heads, but if you use an 885 head it will be lower. it's also the wrong shape for a good quench area on the 885 head..