O.K. O.K. I am prepared to have my ass handed to me here, but before I get the slap I possible deserve, Are you telling me that the 1.8T engines did not have an iron block?
please find the following: The Audi AEB engine is a 1.8l DOHC 20v turbo charged and intercooled inline 4 cylinder with an iron block and an aluminum head.
here:
http://www.phonecallsfromthedead.net/th ... /A4_1.html
Not the most reputable website but one of many that came early in the listing when i googled 1.8t block/iron block. All the listing that I could be bothered to read mentiond iron as a material.
Having to make a brand new engine block out of iron, with it's weight penalty and expansion characteristics in relation to an ally head must be a hard pill for any top level designer to swallow especially with advances in cost effective new tech in many other areas outstripping engine blocks but on production engines whih high cylinder pressures, i.e. turbo's and deisels it is a very attractive solution. No need for a dissimilar bore material which means a one part block rather than five (liners) which in turn means far lower machining and assembly costs, plus you get increased stability (if designed right) around those highly presurised bores.
To make and iron block and then Nickasil plate it??? really??? tell me I'm wrong and that after using the cheapest solution on the table they then complicated matters almost out of sight and plated it using, what in mass production terms is a fickle, slow and ultimatly very expensive process?
What you are saying about the tooling makes total sense..... on the new generation of engines, i.e. 2.0t which I heard were ally, since I left the industry about that time I have stopped following developments as closely so would take your word on it.
And yes, what skunk said is pretty much the problem, condesation in the cylinders formed between engine uses would mix with the sulpher in low quality fuels forming sulpher dioxide which would attack the nickasil. Lots of short journeys would excaserbate the problem, all damage was irreversible and as the damage was different in nature to the simple 'smoothing' of iron bores by wear over time. The consequences were more severe and failures could potentially be more serious than drinking oil. Engine seizures were a potential, although unlikely side effect.
Panic, a lack of understanding and mounting warranty repair costs caused the phasing out of Nickasil by BM and Jag and it even though all fuel's have improved, particularly with respect to sulpher content since the initial problems, Nickasil's return to the mainstream has been slow.
Mass producers of sports bikes have been one of the few to carry on using it consistently during the 'dark' years, being unable to accept the trade off associated with alternative materials/process's (possibly also happy that countries with very low fuel quality possibly also had the odd pothole or two in their roads, therefore orders for Fireblades and the like were unlikely to suffer too badly
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A lot has happened since I last tried explaied all that to anyone so I reserve the right to correct small discrepancies that have crept in due to poor memory! but essentially F1eng, is that pretty much the case?