To MB or MC?

[isham-research.freeserve.co.uk at pop.pol.net.uk]

> Can anyone tell me the major differences between the MB and MC motor? I
> need to build one for high horsepower, and would like to know which is a
> better candidate.

Well, since I've driven 110,000 miles behind an MB and 42,000 behind an
MC, both of which I still own and wrench ...

The MC is a hydraulic tappet engine packaged for the Type 44 engine bay.
Two forms - single knock sensor controlled by MAC11 and twin knock
sensor controlled by MAC14.  Both forms support emission controls -
OXS sensor and the like.

A version of the first MC was adapted for european use by deleting the
OXS sensor, which was not a legal requirement at the time.  This was the
1B engine controlled by the MAC12D - again packaged for the Type 44
engine bay.  Orin Eman has shown by disassembly that the MAC12D code
is identical to the MAC11 code with the (very few) variables and code
dealing with emission controls deleted.

The MB is exactly this engine - single knock sensor and no OXS -
repackaged to fit into the Type 85 engine bay.  It also uses the MAC12D,
although some (not all) MAC12Ds found in MB-engined cars are marked
'ur-quattro only'.  I think this is the only place I've seen the
word 'ur-quattro' used officially by Audi at the time of production.

Physically (crank, pistons, cam, etc) all four engines are almost
identical.  I believe the MC-2 is a minor exception because of some
cam changes, but that's about all.  The peripherals (air filter box,
plumbing, etc.) are different shapes although the key fuel injection
components (metering head, frequency valve, injectors, system pressure
regulator, control pressure regulator) are the same.

Essentially, for North American ur-quattro owners, the MB's peripherals
provide a 'stock' way of mounting an MC engine into a Type 85.

There are photographs of a Type 85 MB installation and some other details
on Scott M's web site.

--
 Phil Payne
 UK Audi quattro Owners Club
 http://www.isham-research.freeserve.co.uk/quattro
 Phone +44 7785 302803   Fax: +44 7785 309674