Re: 931/16v interchange

[John Larson <jdlarson@ix.netcom.com>]

As a veteran wrench of the 100LS years, as well as the first owner of
one of the earliest 931s, I would like to offer my comments. The 924/931
block bears only a casual visual similarity to the block of the 100LS,
which was a pushrod motor. There is NO truth to the rumor that they will
interchange. The 924 block is the same as the 931, with the exception of
the crankcase breather, which CAN be changed over. There may exist a
twin cam experimental version of the 931 motor, but I think not. As I
recall, and my memory is vague on this, the GTRs were all SOHC. 
Because all the later inline Audi DOHC motors were either 5 cyl 20v or 4
cyl 16v and are based on the (somewhat) modular Fox/Rabbit system, not
the 100LS/LT/924 system, there can be NO interchange.
 
As a former owner of several 100LS cars, a couple of 924s, and a 931, I
share your pain, but I've learned my lesson and have moved on with my
life. The last customer 931 engine I did (in 1991) cost over twice what
the car was worth when we were done, and it was a VERY nice, one owner,
car. 

In closing, you could have a cylinder head developed and manufactured,
per the wise comment of my P-car school instructor. "You can do anything
you want, my friend, if you have the money." You'd still have a 931. 

John