Minutes of the 'P1 Operation' meeting of 1 April 1964

In this document

This document is a printed Citroën form (ref. 1.44.23, 10-61 FL 12.000), filled out to report on a working session held on Friday 1-4-64 at 2:30 PM, in Mr. Cadiou's office, dedicated to "P1 OPERATION" p. 2. The list of attendees is extensive: Messrs. Allera, Barthelemy, Cadiou, Caneau, Capsek, Chalard, Cordier, Daumain, Deblasis, Forceau, Hondet, de Lassus, Louis, Magès, Mitouard, Nougarou, Pompon, Renaud, Roche J., Sallot, Seznec p. 2.

2-stroke / 4-stroke comparison

Handwritten notes report a "quick presentation of the 2-stroke principle": permeability is said to be constant ("fonor N"), unlike the 4-stroke; a 2-stroke engine can only be supercharged by pressurising the exhaust; at high speeds, it would not produce more power than a 4-stroke of equal displacement; finally, idle regulation would be easier on a 4-stroke p. 2.

Scavenging and compression of the P1 engine

The document defines the "scavenging ratio" (ratio between the quantity of air sent and the displacement) and "scavenging efficiency" (ratio between the fresh air stored and the displacement) p. 2. It indicates that the compression ratio of the P1 engine is 12, well supported at high speed as well as at lower speed, the scavenging ratio then increasing and cooling better p. 2. The consumption of the P1 is noted at 185-195 g/hp/h, with an additional 20 g/hp/h linked to scavenging p. 2.

Sketches

Two blue ink sketches accompany the text. The first plots, as a function of speed N, the power of the P1 alone, the scavenging power (called "cubic"), and the resulting power, with the remark that the P1 "is limited due to [the] increase [of] compression" p. 2. It also mentions an independent power supply via an auxiliary engine driving a compressor p. 2. The second sketch compares "permeability" curves at 2000 and 5000 revolutions/minute of the main engine, with the values 5700 and 6870 marked near the N axis p. 2.

Context

As a reference external to the document: in the 1960s, Citroën explored experimental engines, including two-stroke engines, as part of its research into future powertrains. Having joined Citroën in August 1925 and remained with the company for 49 years (autobiographical notes), Paul Magès, best known for the hydropneumatic suspension for which he wrote the first plans as early as February 1944 (hydropneumatic suspension plans), participated more broadly in the brand's technical design work, which explains his presence at this type of meeting.

Archivist's perspective

This report illustrates the teamwork and technical synthesis carried out collectively at Citroën: about twenty engineers and technicians gathered around the question of the operation of an experimental engine designated "P1".

It seems that this document is part of a series of works carried out in the spring of 1964 on this engine, as suggested by the handwritten notes and curves on the power and scavenging of the auxiliary P1 engine, dated the same day, as well as the "REA meeting regarding the 2-stroke engine" folder, held two days later.

The presence of Paul Magès among the participants testifies to his involvement in engine subjects going beyond just suspension, confirming the breadth of his role as an engineer, then deputy head of Super-Control (autobiographical notes), within the Citroën design office.