[V8] Spectral analysis V8 ABH and PT blocks

[Jason Wilkerson]

That is some interesting info to have on the makeup of the blocks, thanks.  I always made the assumption that the oil usage was strictly because of the PCV system.  The reason I felt this was because if you look at the actual system and how it is plummed, it just makes sense.  If you go down a long hill and at the bottom you hit the gas you will see a small plume of smoke from our cars.  The reason for this is simple: one of the 'breather' hoses for the PCV is located directly above the throttle plates.  When you allow the engine to engine brake with the throttle plates closed (as in a downhill situation) you create enough vacuum to suck up oil into this hose, once you hit the throttle again it pulls it on through the motor and out the tailpipe.  I would assume this problem to be worse on a manual transmission car BTW.  

--- On Fri, 12/11/09, Bastian Preindl <bastian at preindl.net> wrote:

> From: Bastian Preindl <bastian at preindl.net>
> Subject: [V8] Spectral analysis V8 ABH and PT blocks
> To: "'V8 Audi Fans'" <v8 at audifans.com>, "'200q List'" <200q20v at audifans.com>
> Date: Friday, December 11, 2009, 7:10 AM
> Dear list,
> 
> as a follow-up on our discussion two years ago regarding
> the "real" 
> cylinder coating and/or block alloy in the Audi V8 engines
> PT (3,6) and 
> ABH (4,2) I can now provide you with some new details and -
> finally - 
> facts. As you may know there were always rumours going on
> that the ABH 
> blocks may be NiKaSil coated which shall explain the large
> oil 
> consumption of some 4,2 V8s, even though it didn't make a
> lot of sense. 
> We now have the results from the spectral analysis of both
> the ABH and 
> the PT blocks and they are as follows:
> 
> 1) PT and ABH are made of completely identical alloys
> 2) Both blocks are AlSiCu alloys
> 3) Both blocks have etched cylinder walls
> 4) The common name of the alloy is G-AlSi12 and is a
> "standard material" 
> for strong requirements on solidity and strength - a
> typical alloy for 
> combustion engines
> 5) Additionally vestiges of iron ( Fe, approx 0,67%) have
> been detected, 
> supporting the solidity as stated as requirement in 4)
> 
> For most of you all this is probably no surprise - but back
> in Europe 
> this has busted a myth which was spread around since ages
> and caused 
> numerous V8 owners to sell the car as they thought its
> engine is 
> irrepealable broken (this includes myself). Still, the
> question is given 
> why some ABH need more oil than fuel (>3 liters is not
> exceptional) even 
> after the heads have been overhauled but it is at least
> proven that it's 
> not cause Audi has used NiKaSil for some strange reason on
> this and only 
> this engine...
> 
> Credits to Manfred M. from Augsburg for his efforts!
> 
> Best regards
> 
> Bastian
> 
> PS.: I've sent this also to the 200Q list as this might
> interest future 
> and past V8 owners as well and the V8 is usually also a
> lively topic in 
> the 200Q circles
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