E30 Zone

Am I missing something Dave? That's clearly an E for early HC, K is later LC.

high comp bert

Simon13 wrote:high comp bert

+1 oops

According to realoem 256E2 is from 9/87 on with no cat so i would say low comp.

256E1 is upto 9/87 with no cat so i would say that is a high comp.

256K1 is from 9/87 with a cat (the K in 256K1 is an abriviation for Katalysator which is german for catalitc converter so this will also be a low comp engine.

http://www.realoem.com/bmw/showparts.do ... g=11&fg=05

I will confirm this tomorrow.

I gather all the 25 6E blocks are high compression. My 1988 F-reg 325iSE had one and it went like stink!

256E2

25 denotes the engine size

6 denotes the number of cylinders

E denotes engine concept with E being injection

2 denotes the differentiation index with 2 being the second, ie low comp as that came after 1, high comp.

See page four of this very usefull PDF file.

http://www.ge39.com/files/zeigeinfo.pdf

I guess thats squashed that myth!

bss325i wrote:256E2

25 denotes the engine size

6 denotes the number of cylinders

E denotes engine concept with E being injection

2 denotes the differentiation index with 2 being the second, ie low comp as that came after 1, high comp.

See page four of this very usefull PDF file.

http://www.ge39.com/files/zeigeinfo.pdf

I guess thats squashed that myth!

This needs clarifying? Everyones been led to believe 6E high comp. 6k low comp.

bss325i wrote:256E2

25 denotes the engine size

6 denotes the number of cylinders

E denotes engine concept with E being injection

2 denotes the differentiation index with 2 being the second, ie low comp as that came after 1, high comp.

See page four of this very usefull PDF file.

http://www.ge39.com/files/zeigeinfo.pdf

I guess thats squashed that myth!

As interesting as that is, it doesn't specifically define 1 as high comp and 2 as low comp

So who fancies dismantling their engines and doing a volume measurement..??

only joking...

Speedtouch wrote:

bss325i wrote:256E2

25 denotes the engine size

6 denotes the number of cylinders

E denotes engine concept with E being injection

2 denotes the differentiation index with 2 being the second, ie low comp as that came after 1, high comp.

See page four of this very usefull PDF file.

http://www.ge39.com/files/zeigeinfo.pdf

I guess thats squashed that myth!

As interesting as that is, it doesn't specifically define 1 as high comp and 2 as low comp

Good point. Can you explain why you think the 1 and 2 will refer to the comp ratio?
What's the engine code on yours barry?

Because the the E and the K refer to type, not compression ratio. E is for fuel injection and K is for catalytic converter (on M10, M20 and M30 only)

Its clearly states that on page 4 of that PDF file (of an official BMW document) in the link i posted.

The digit after E or K denotes the differentiation index, ie 1 being the first, 2 being the second.

256E1 = upto 9/87 non cat and of the first differentiation, ie high comp (9.4:1)

256E2 = from 9/87 non cat and of the second differentiation, ie low comp (8.8:1)

256K2 = from 9/87 cat (and i think cat prepped) and of the first differentiation, ie low comp (8.8:1)

I will have to check what mine is Dave but it think its 256K1, mine is cat prepped but doent have the cat itself.

But how have you drawn the conclusion that the differentiation number refers specifically to compression ratio?

The document appears to make no validation on this, unless I missed something...

Because the high comp came out before the low comp.

Something else has come to light that may throw this theory out.

More tomorrow.

Early ones are 9.75.1, later plakky bumper cars are either 9.4:1 or 8.8:1.

Why do BMW state only two compression ratios for the M20B25

9.4:1 or 8.8:1?

They don't, they state three. 9.75 in the old chrome bumper version handbook and the other two in the later handbooks.

So the above engine number is that of a 9.4:1 comp ratio engine???

Andy, i checked it out at work on BMW TIS. It only states 9.4:1 and 8.8:1.

I checked '85, '86, '87, '88, '89 etc.

No mention of 9.7:1.

Well, then TIS is wrong. The original 1985 owners handbook states 9.7, so does the original 325i technical bulletin from 1985 and I got a mate to check the Mahle piston catalogue which actually states 9.75 on early cars.


To check, I trawled through ETK and found three different slugs (standard bore Mahle)

Up to 9/87 11251708861 = this must be the 9.7

From 09/1987 to 06/1988 11251718924 = early plastic bumper, probably 9.4.

From 06/1988 11251735760 = Later plastic bumper, probably 8.8

So, 25 6E1 probably refers to 9.75 CR while 25 6E2 is the 9.4 CR (presumably).

You are right about three specific dates for pistons but interestingly on the etk it lists 3 different engines.

256E1 Up to 9/87 11001730858

But what is missleading is this, both engines are listed from 9/87, neither of them upto 6/88

256E2 From 9/87 11001730889

256K1 from 9/87 11001730862

Speedtouch wrote:So, 25 6E1 probably refers to 9.75 CR while 25 6E2 is the 9.4 CR (presumably).

This is what its begining to look like i guess.

Strange that the most up to date version of BMW's TIS (Technical Information System) only mentions 9.4 and 8.8.

Conflicting data doesn't make things easy!

Where's Ant when you need him? I'm sure he knows the definitive answer!