Help needed

[jeffstoo]

Hi
Can anyone help identify my engine block?
Just cleaning the block ( taken out of my 1992 3B coupe ) and I am puzzled!
There is no engine no, the no on the block is 054103021, which doe's not seem to fit with what should be in a 3B. There is 25L and 91 cast into the block, the bore is 80 mm, I cant measure the stroke unless I put the crank and a piston back in but the rods are about 144 mm. Any help appreciated.

[rxl]

It's my old 3b block so you should measure the bore again.

[rxl]

to put it simple you have 3b

[jeffstoo]

Thanks for reply rxl. I doubt that it is your old block, but I could be wrong! I have owned the car for 15 years and it's the first time that the engine has been out in my ownership. When you say measure the bore again do you mean that standard is more than 80 mm or your block was rebored?

[rxl]

Sorry for my bad English.. I had an 3b coupe with the same casting on it.. There are no numbers like 3b.. I have a Adu, and 2 aby blocks and none of them have any marks on it that they are Adu or aby. As I remember the standard bore is 80.5? But I might be wrong but is should be right..

[twoqu]

The standard bore size is 81.01mm!
Clean a piston top and you should see 80.98mm somewhere.

[rxl]

The standard bore size is 81.01mm!
Clean a piston top and you should see 80.98mm somewhere.

true true 81,0 × 86,4 mm

[jeffstoo]

Thanks Guys.
That confirms I have a 3b block I got a bit concerned when I could not find an engine no. twoqu, just had a look and found 80.98 on pistons.

[rxl]

Well glad that you are satisfied with it

[twoqu]

Not sure why Audi started to put the engine number on the cylinder head as opposed to the block. More likely to replace a cylinder head than a block.
However if you had asked us where the engine number was we would have told you its on the cylinder head!

[rxl]

It was cheaper to put numbers on head [emoji23]

[UrS4boy]

20VT Engine Numbers: Location and AAN, ABY and ADU Engine Build Dates

However if you had asked us where the engine number was we would have told you its on the cylinder head!

Yup

20VT Engine Numbers: Location and AAN, ABY and ADU Engine Build Dates:

http://forums.quattroworld.com/s4s6/msgs/123036.phtml

[jeffstoo]

Found engine number on cyl head and all is well I have a Bently manual, I know it doesn't cover a 3b but it says the engine no is stamped into the side of the block. When I couldn't find the engine number I assumed the number on the block would match with etka but it didn't. That's when the doubts set in. Anyway thanks to all your help I now know what block I have and my engine build can continue.