A day's fun

[quk@isham-research.demon.co.uk (Phil Payne)]

I just want to record (and I'll do it later in more detail, but I'm
knackered, filthy and hungry) that I spent a _FASCINATING_ day today
at Historic Motorsport in Daventry - David Sutton's place.

(and yes, Jouko, 'number 9' is going to Finland.)

David asked me to take a look at Hannu Mikkola's 1983 car.  It has a
Pierburg injection system - about which Scott Mockry seems to know
100x what Pierburg knows ... all archives have been destroyed.

But tucked away in an abandoned filing cabinet at Historic Motorsport
I discovered a Pierburg manual.  Not only for the system the car used,
but specifically for THAT SPECIFIC CAR!!!!

In Kraut, of course.  But nonetheless fascinating, and now secure for
future generations.

For the cogniscentii - The Pierburg system uses no air mass sensor.

The primary inputs are throttle position and rpm to the metering head,
and boost level to the control pressure regulator.  Via the "ECU",
inlet air temperature and altitude are fed to the control pressure
regulator via a solenoid biasing device.  The control pressure regulator
is fascinating, using what I can only describe as a 'moving platform'
controlled by atmospheric pressure, a heated 'expanding cell' (wax?)
and a set screw.  Everything (EVERYTHING!!) is adjustable, all the
electrics are duplexed and there is a defined mechanical 'limp home'
mode throughout.

The fuel distributor is equally fascinating.  Instead of moving up and
down as in the standard Bosch CIS system, the 'plunger' rotates. The
'slits' (and that's what they're called in the German) are triangular,
and rotation is the key movement.  The bottom of the 'plunger' has an
arm attached, which bears on a cam.  The cam rotates (a neat stepping
motor servo system) according to rpm - but it also translates linearly
according to the throttle valve position.

The manual makes great capital out of the system's ability to be tuned
(by cutting a cam) for the characteristics of any engine.

There's more.  Lots more.  I'll (eventually) translate the manual for
'Pierburg 83 Group B Audi Rally Car Fuel Management System'.

What was the ultimate cause of Pierburg's problems?  Over-dependency on
carburettors when the world was going to FI?  Did they get blasted by
Bosch's patent lawyers?  Or was it just that burning chips is easier,
cheaper and much more flexible than grinding tailored cams?

--
 Phil Payne
 UK Audi quattro Owners Club
 Phone: 0385 302803   Fax: 0870 0883933