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Audi engines 1B and MC

Response to private email, copied to the list (anonymized) for peer

> My Audi is a 1990 100 TQ with the MC (-2?) engine with dual knock
> sensors, MAC-14 ECU etc. This engine was also used for the 200
> models here in Sweden until the 3B engine was introduced. I do
> know, however, that in the UK (and possibly other countries),
> different engines were used in the 200 models, denoted 1B and 2B
> with 200 hp and 190 hp respectively (the later for the auto
> transmission cars). These engines seem to be quite similar to my
> MC engine except for slightly higher compression ratio (8,6:1),
> single knock sensor, higher boost, different> cam, different ECU
> (MAC-12 ?) etc. >

The basic difference is emission controls.  The engines used in the
USA, Sweden and Switzerland during the mid and late 1980s were very
similar and in most cases bore the same codes.

These engines were also used in countries that did not have emission
controls at the time, such as the UK and Germany, under different
codes.  Thus the USA/Sweden MC-2 (which you have) is mechanically
identical to the 1B used in the UK.  It's also identical to the MB
fitted to my ur-quattro, except that physical constraints have given
me a different airbox, intercooler, etc.

The upside is more bhp.  The downside is the lack of lambda sensor
feedback in non-WOT running, and a _very_ crude enrichment system
in WOT running.  The MC-2 is by far the most elegant solution to these
problems, despite its lower nominal output.  I say "nominal" because
the 1B and MB are such dogs to set up correctly, that the MC-2
probably outperforms them in practical applications.

> The stock 165 hp my car produces is OK but not exciting. I know
> there are several tuning companies offering chip(?) upgrades to
> the MC engine, but the problem is I have a hard time trusting
> these companies, e.g. it> is very hard to make them explain what
> modifications they have made etc.

Yes.  And this is a problem, because it's not just about boost level
with these engines, but also about ECU control of enrichment.

Essentially, the computer program makes decisions based on rpm, boost,
temperature(s), etc., but it also assumes a certain engine geometry.
If you change the cam, port the heads, increase the air filter flow
rate, etc., etc., you _HAVE_ to tell the ECU code.  I firmly believe
that the ChipMeisters (excluding present company) just fiddle with
maximum boost levels.

> This is where the 1B engine comes in. It is a factory product and
> its 200 hp is approximately what I am looking for. Therefor I
> have a couple> of questions:

- Do you have the specifications for the 1B engine (boost, torque,
  cam timing, ECU used etc.)?

I can probably get them.

- Is the 1B ECU code usable (with modifications needed) in a MAC-14

Yes, but you would lose significant function.  1Bs don't have lambda
sensors, for instance, or differential fuel pressure controls.

- Would it be possible to get my hands on the 1B ECU code?

Question of finding an ECU somewhere and dumping it.  Scrapyard?

- If 1B code is not usable, what other modifications do you

Intercooler improvements do not affect the ECU's view of engine
geometry, and are relatively cheap and trouble free.  My advice to
people seeking extra performance is _ALWAYS_ to make sure they're
really getting what Audi intended them to get - check the WOT switch,

 Phil Payne
 Phone: 0385 302803   Fax: 01536 723021
 (The contents of this post will _NOT_ appear in the UK Newsletter.)