The Displacement Conundrum

[SMILLER@xxxxxxxxxxxxxx]

Boy, Robb, the Sport vs. non-Sport thing was complicated enough, are
you sure you want to get into the displacement thing?

>Date: Wed, 2 Dec 1998 10:20:29 -0600
>From: rsalzmann@domain.elided
>Subject: Re[2]: When does the "s" stand for "sport"?
>
>     OK, my curiosity is peaked.  what do the letters in 635CSi mean?
>     Coupe, Sport, Injected?  Also, I have been assuming for some time
>now 
>     that the last two numbers in the model designation e.g. 325 750 etc. 
>     refer to the engine displacement in litres/10: 325 = 2.5l 635 = 3.5l 
>     and so on.  Is this right or just a neat coincidence?
>     
>     robb
>     BMW CCA #161249
>     86 635CSi

1.  Yes, CSi is Coupe Sport injected.

2.  In the old days (through maybe 1979 if I'm not mistaken), the last 2
digits were indicative of the displacement.  In the U.S., they sold a 530i (3
liter) through 1978.  In 1979 they put a whole new engine management
system on the same car, and also dropped the displacement to 2.8 liters. 
So it was called the 528i.  Power output was about the same, but (as I
was told, but I don't know this for sure to be true) the public perceived
that they were getting "less" of a car, so even though it was a better
car, sales dropped.

In 1980 they lowered the U.S. 320i displacement from 2 liters to 1.8 liters,
along with similar engine management system changes.  Not wanting to
experience a repeat in lower sales, they did not change the model ID.  So
there were 2 liter and 1.8 liter 320is running around.

For the big 6 cylinder engines (M30?), I seem to recall that the
displacement was slightly lower than the badge indicated, but I'm not
positive.  So, the 533i, 633CSi, and 733i had 3.2 liter engines, and the
535i, 635CSi, and 735i had 3.4 liter engines.  However, they were close
enough to reality, so we'll let that go.  Or, I could be wrong.  Oh, and the
745i?  It was a turbocharged 3.5 liter.

With the E30, the ID was changed on the 4 cyl car to 318i.  But, the 325e
had a 2.7 liter engine.  I'm not sure why.

More recently the V8s received displacement increases, but the IDs
didn't change.  The 530i engine displacement was increased (to ???) but
is still called a 530i.  I think.  But it isn't available new any more in the U.S. 
The 540i engine went to 5.4 liters.

The 4 cylinder E36 cars all got 1.9 liter engines a few years ago, but
they're still called 318i, 318is and 318ti.

I'm pretty sure this is documented more succinctly on someone's web
site, but hell if I know where to find it.

Anyone who knows where I made mistakes feel free to correct me. 
(Yeah, like you need my permission to point out mistakes.)

OK, what's the next can of worms we can open to confuse everyone?

Scott Miller
Golden Gate Chapter
BMW CCA #44977
1990 325i/is hybrid that actually has a 2.5 liter engine

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