Press clippings: Zénith CL petrol injection analysed by the Revue Automobile (1974)

In this document

General presentation

The article, signed by Olaf von Fersen, appears in the Swiss Revue Automobile No. 36 of 22 August 1974 p. 29. It focuses on the Zénith petrol injection device, in particular the CL execution, whose fuel metering is carried out "as a function of the volume of air drawn in" p. 28. The clipping retains a stamp from the Centre Technique B.E.A. — Documentation Vélizy p. 28, attesting to its preservation for technological monitoring purposes at Citroën.

History of the system

The text traces the development of the device at the Deutsche Vergaser Gesellschaft (DVG), a subsidiary of Solex: work initiated "about fifteen years ago" at the Institute for Piston Engines in Braunschweig under Kurt Löhner and Günther Härtel, first patent for a "carburation device" in February 1961, then a May 1965 patent for a "fuel supply device" p. 29. The DVG research centre in Neuss opened in 1970; management passed to Asoke Chattopadhay in 1971 p. 29. Version A was presented in November 1971, followed by versions B, C, then CL, shown at the Geneva Motor Show p. 28.

Technical operation

Fuel is drawn by an electric pump via a filter, maintained at a pressure of 2 to 3 kg/cm² by a reduction valve, and distributed by a grooved piston system rotating according to the position of a three-dimensional cam p. 27, 30. The CL execution adds an air flow meter compared to that of the Bosch K-Jetronic p. 28-29. The injection nozzles also receive air to refine atomisation, particularly at idle p. 27.

Industrial aspects and tests

The text mentions a target cam cost of "less than 1 DM" p. 27, 30, long-term tests underway at several European manufacturers, and a target price comparison at the level of a "double carburettor device" type Zénith INAT p. 27, 30. On a Ford competition engine, the power consumption of the injection is estimated at "about 1.5 hp at maximum" p. 30. Tests on a six-cylinder BMW engine show exhaust results below the limit values of the European cold test p. 29.

Context

This clipping is part of the broader context of the anti-pollution fight of the mid-1970s and the revival of petrol injection, then dominated in Europe by Bosch (K-Jetronic and L-Jetronic systems). Citroën, via its Technical Centre, closely followed these competing developments as part of its own research into carburation and engine supply. This piece dates from the last year of Paul Magès' career at Citroën: having joined in August 1925, he was still working at the Super-Contrôle before retiring in September 1974 after 49 years with the company (photographs of the retirement), to then retire to Ramatuelle.

Archivist's perspective

This document clearly illustrates the technological monitoring practice of the Citroën documentation department: keeping and annotating foreign technical articles on competing systems (Zénith, Bosch) to inform internal choices regarding injection. It seems that this clipping completes a larger set devoted to carburation kept in the same file, notably the clippings on the Bosch K-Jetronic and the translation of the ATZ article on the K-Jetronic, to which the text explicitly refers p. 28-29. The documentary interest lies above all in the technical detail of the diagrams of executions A, C and CL, valuable for comparing the mechanical and pneumatic approaches to air/fuel metering at this pivotal time.