Temperature test report on GS 1015 engine in winter conditions (1972)

In this document

This document is a handwritten graph on graph paper, comparing the temperatures recorded on the GS 1015 engine: engine oil, carburettor intake and exhaust manifold, as a function of time (in minutes) and then of stabilised speed on the motorway (90 to 140 km/h) p. 2-3.

Two compared tests

The graph superimposes two series of curves, distinguished by colour annotations:

• In red: "Voiture serie + essai serie" (Standard car + standard test), with an outside temperature of 4° during the test, and a cold start with water circulation p. 2.
• In green: "Essai série + volan flasque d'huile sur tubulure + isolation des tubulure par du Fripo flexre [uncertain]" (Standard test + oil baffle on manifold + manifold insulation with Fripo flexre [uncertain]), with an outside temperature of 1° during the test, and a start with the engine having already run, without manifold insulation p. 2.

The curves are annotated by measured quantity: "Huile moteur" (Engine oil), "Entrée carbu" (Carb intake) and "tubulure" (manifold), repeated several times along the plot, apparently corresponding to the different test conditions p. 2.

A handwritten note "Erreur d'echelle" (Scale error) accompanied by up/down arrows appears at the top left of the vertical axis, signalling an inaccuracy acknowledged by the author on a portion of the reading p. 2.

The date 1972 is written in the graph legend p. 2 and recorded alone in pencil on the following page p. 3.

Context

The GS 1015 engine corresponds, in the general context of Citroën production, to the engine of the Citroën GS, a compact saloon launched in 1970 and known in particular for its hydropneumatic suspension — a field in which Paul Magès played a major role at Citroën.

Thermal behaviour tests in cold weather (here around 1°C to 4°C) are, generally speaking in the automotive industry, a classic stage of engine development, intended to verify the temperature rise of the oil and the intake system in real or simulated winter conditions.

Archivist's perspective

This document illustrates, it seems, a fairly technical and empirical comparative test: two configurations of the GS 1015 engine (bare standard, and standard modified with partial manifold insulation) are tested in cold weather and their temperature curves superimposed by hand p. 2.

The presence of annotations such as "Erreur d'echelle" testifies to the care taken in the reliability of the graphic reading, a practice consistent with the workshop rigour found in other notes by Magès from the same period, such as his note to Mr Grosseau on the BHRA (22 February 1972), dated a few months before this test.

The direct link of this thermal report with Magès' hydropneumatic suspension work is not established by the document itself; it is probably a one-off test relating to the general development of the GS engine, rather than his best-known inventions.