[V8] Engine rebuild options

[cobram at juno.com]

 Bastian Preindl <bastian at preindl.net> writes:

> if you need something written I'll have a try in audiv8.com - I'm 
> personally aware of a guy who recoated an ABH machine for a 
> fortune... 

Recoated with what?  

> the NiKaSil issue is discussed since years as lots of ABHs suffer 
> from 
> exhaustive oil loss even with completely overhauled heads. I've had 

I think they're getting their nomenclature wrong.  Overheating is a major
cause of excessive oil consumption in V8Q's (my experience of the years,
anyway.)  Once very overheated, both PT and ABH engines will run fine but
burn excessive amounts of oil IME.

> a 
> discussion with a leading engineering from Audi in Györ, Hungary, 
> where 
> they currently manufacture their V6, V8, V10 engines. He was pretty 
> old 
> and already lead engineer when the V8 engines were manufactured in 
> Neckarsulm. I confronted him with the NiKaSil issue and he 
> confirmed, 
> and also confirmed that the alloying was changed after the issue was 
> discovered. That's what we can subjectively confirm.

Changed to what?  I can't fathom WHY Audi would ever have switched to
NiKaSil.  As stated before, BMW and Jaguar at the time were  spending
million$ of dollars replacing NiKaSil engines, the problem was already
well known by 1991,  does it make any sense at all that Audi would adopt
a process with known GRAVE problems at this point?
 
> Some links as a quick shot:
> 
> http://www.audiv8.com/german/technology/motor.html
> http://www.bobmodifiedbmw.com/CarMaintenance_files/bmwnikasil.htm
> "Porsche appear not to have any problems with their Nikasil-lined 
> 4-cylinder or flat-6 engines, but there are reports of problems 
> similar 
> to that with the BMW both in Audi's and in Jaguar's V8 NiKaSil 
> engines."

There is no mention of NiKaSil in your first link.
The guy in the second link needs to correct his web page, I'll take the
manufacturers word.  OF COURSE Porsche didn't have problems with NiKaSil,
they didn't use it.  The Boxster and the 911 used Locasil.  

The coatings are not all equal, the reason NiKaSil fails is because the
sulphur residue from fuel reacts with condensates in the cold engine to
form sulfuric acid.  This acid then eats away the nickel base (NiKaSil)
and the silicone carbide scrapes off causing bore failure.  Alusil and
Locasil did not suffer from this problem because they are not nickel
based. 

Everything I've ever seen and read shows that Audi never used NiKaSil in
the V8Q's.  

BCNU,
http://www.geocities.com/cobramsri/
"God's a kid with an ant farm, lady. He's not planning anything."