Date:         Sun, 20 Sep 1998 20:21:38 -0400
Reply-To:     Martin Jagersand <jag@CS.ROCHESTER.EDU>
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
From:         Martin Jagersand <jag@CS.ROCHESTER.EDU>
Subject:      Injection pump book tip.
Comments: To: VWDIESEL@PAS-NT.PAS.ROCHESTER.EDU, vanagon@vanagon.com

I just read through a new edition (1994) of Bosch's "Diesel
fuel injection" book. I can definitely recommend it. Has a
good chapter on the basics of the various Diesel designs,
a chapter on exhaust emission, and what can be done to lower
them and last but not least the latter part of the book is devoted
to the VE injection pump in the VW vans and cars.

It's interesting how little the VE pump has changed in the
last 25 years. Essentially the same pump was in the first
VW diesels in the 70's as is in the newest TDI's! In fact
in  a sense the TDI pump is simpler than the older ones.
A lot of the mechanics regulating the control sleeve (governor,
boost and altitude aneroids) have just been replaced with a
simple solenoid (and the functions are now computerized.)

The only other substantial change is that the timing advance
is now both load and speed dependent by means of a small
solenoid leak valve in the timing regulator. This makes
the new diesels quieter in normal operation. Max advance
occurs only at full load.

Ever wondered how the TDI two stage injection works? It's
in the injectors, not the pump. The injectors have two
springs with two opening pressure settings. The pre-injection
opens first, the the main injection.

And for those power and speed nuts, Bosch specifies that the
VE pump (I assume any basic VE) can be tuned up to deliver 25kW/cyl.
(You supply the air ;-)

/Martin
--
Martin Jagersand                 email: jag@cs.yale.edu
Computer Science Department             jag@cs.rochester.edu
Yale University

        Slow down and visit the VW diesel Westy page:
          WWW: http://www.cs.rochester.edu/u/jag/vw
-------------------------------------------------------------------