Revue Automobile clippings on the Bosch K-Jetronic injection system annotated "M. MAGES" (1972-1973)

In this document

These five pages are clippings from the Revue Automobile, signed by journalist Olaf von Fersen, dedicated to the new Bosch K-Jetronic petrol injection system. Page 75 bears the full title of the article, "A new Bosch system without drive control", dated "11.10.1973 No. 43" p. 75; page 71 bears the mention "IIIrd SHEET 18.10.1973 No. 44" p. 71, page 74 another date "5.10.1972 No. 43" p. 74 — the dates differ according to the sheets, a sign of a compilation of several issues of the magazine.

General principle

The text explains that the "K" stands for kontinuierliche (continuous injection), as opposed to the electronic Jetronic whose injectors are controlled by an opening duration p. 75. The system is presented as "entirely mechanical", without "any electronic element" p. 75, even if it includes an auxiliary electrical part: pump, heating resistors for the bimetallic springs, safety cut-out p. 71.

Described operation

A shutter disc floats in a conical funnel and rises proportionally to the intake air flow; this movement is compared to the float of a flush toilet p. 74-75. It controls, via a lever, a control plunger sliding in a "slotted cylinder", which doses the petrol sent towards differential pressure valves and then towards the injectors p. 71-72. The system pressure is 4.7 bar, the spray pressure 3.3 bar p. 71. A thermal regulator with a bimetallic spring enriches the mixture when cold p. 71, 73.

Technical elements and data

Other information

The article cites the Bosch project director, Mr. Knapp, mentioning future developments in the face of tightening anti-pollution standards p. 72. It mentions that Porsche chose the K-Jetronic for the American and then European 911, and that VW and Daimler-Benz are interested in it p. 71. An injection pump with a titanium camshaft for a Porsche 917 Can-Am Turbo engine is described in the margin p. 71, 73. Pages 71 and 75 bear a handwritten note "M. MAGES".

Context

The K-Jetronic, developed by Bosch in the early 1970s, remained in use on many European vehicles (notably Porsche, Mercedes, Volkswagen, Volvo) until the 1990s, before its gradual replacement by electronic systems (L-Jetronic, then digitally controlled multipoint injection). The Revue Automobile (Swiss) was a technical publication followed by automotive industry engineers of the time.

At Citroën, where Paul Magès worked on hydropneumatic suspension, the question of petrol injection and the improvement of combustion was part of the growing concerns related to the anti-pollution standards of the 1970s — a context external to the document, but which sheds light on the interest Magès may have taken in this reading.

Archivist's perspective

The repeated presence of the handwritten note "M. MAGES" p. 71, 75 suggests that these clippings were personally kept, and undoubtedly annotated, by the engineer — probably to follow competing innovations in engine fuel supply, a field related to his own work on hydraulics and pressure regulation.

It seems that this file documented a technological watch rather than a project directly linked to hydropneumatic suspension: the principles of differential pressure regulation and continuous dosing, described here for petrol, present a striking conceptual kinship with the logic of hydraulic correctors and regulators that Magès was developing elsewhere.

This document is part of a larger collection on carburetion kept by Magès, notably the translation of the 1973 ATZ article on the K-Jetronic and the original German text by Schwarz, Stumpp and Knapp, which technically deepen the same system — a sign of a sustained and documented interest in several sources for this Bosch device.