Warm Dauphine

A Red Renault Dauphine with engine modifications by the Performance Equipment Co., of Liverpool, came along for test last month. This car carries much extra equipment, such as radio, Webesto sunshine roof, Lucas fog- and spot-lamps, reversing lamp, undersealing, etc. The engine modifications consist of raised compression-ratio, equalised combustion chambers; twin S.U. H1 carburetters on a ram inlet system, a cold-air inlet box to each carburetter intake corresponding with an air inlet scoop on the bonnet lid, four-branch exhaust manifold terminating in a transversely-mounted silencer, and an exhaust Booster Unit also mounted transversely, with forward-pointing air intake; it is claimed that flow of air past the exhaust tailpipe from this Booster Unit exerts an extractor effect. The makers claim virtually the same b.h.p. at the rear wheels, i.e., 27½, as Gordini claims for his Dauphine conversion. They hope to sell their conversion kit for about £30: we quote from their own handout:—

“The main effort was put into the manifolding and here a combination of ram inlets and tuned or neutrally-tuned exhaust system was used. On the inlet side ram inlet pipes were designed and calculated to achieve maximum ram effect at 3,800 r.p.m, which is approximately 16½ m.p.h. in first, 34 in second and 57 in top. The exhaust manifold was designed for maximum pulse effect utilisation—note very critical angle of branches with mean exhaust path to get minimum pulse reflection break up at branches and maximum scavenge efficiency. Two silencing systems are provided to fit on to this manifold as alternatives. One is a Performance Equipment designed and manufactured straight-through silencer to bring the total length to correspond to the tuned ram point of 3,800 r.p.m., and the other is a neutrally-tuned system as fitted to the test car for road use, consisting of a straight-through silencer together with a transversely-rnounted exhaust Booster Unit with special air inlet system to pick up underneath the car and so enable the transverse mounting of the Booster Unit. By this means a completely neutrally-tuned exhaust system was obtained which, in conjunction with the ram inlet pipe. gave some degree of ram. for acceleration but gave a smooth performance throughout the range, usually associated with a neutrally-tuned system. When the ram-tuned exhaust system without the Booster Unit is used an increase in power is obtained at the ram point at the expense of power over the rest of the range. Hence, for road use the neutrally-tuned system. using the Booster Unit, is preferred.”

After reading this we hastened away to our marked-out ¼-mile to see how this modified Dauphine would perform. The initial impressions were that exhaust noise is excessive, the throttle linkage impossible, but, that, as claimed, the speedometer is virtually accurate. Incidentally, normal Premium petrol is used, the car came with its original A.C. plugs in use (one burnt out and was replaced by a Bosch plug), and the engine, which consumed quite a lot of water but no oil, had its sump filled with Acoustol 100% Pennsylvanian; as this oil isn’t freely obtainable it is necessary to stow a can of it in the car. A manual ignition control is fitted and a rich-mixture control on one carburetter only. A cold start proved impossible until the carburetter air boxes had been stuffed with rag.

The Performance Equipment Co. quote the weight of their Dauphine as just over 16½ cwt., but a weighbridge confirmed it to be exactly 14 cwt., with approximately 2 gall. of petrol. They mention that the roof slats cause air drag, but so must the roof radio aerial. We doubt whether the exhaust Booster Unit has any appreciable effect on performance, and wonder if tests of air turbulence beneath the car were made before positioning its air intake at 90 deg. to the extractor pipe? Anyway, Ferrari tried a similar form of exhaust extraction and threw it away as useless.

Engine speed is limited to 6,000 r.p.m. by retention of standard valve springs; resulting in maxima of 26 m.p.h. in first gear and 54 m.p.h. in second gear. In top gear the speedometer goes to the stop at 75 m.p.h. down long straights, suggesting a maximum of over 80 m.p.h. Driven fast at night round a test circuit in Hampshire, this Dauphine proved as fast as, but no faster than, a normal Hillman Minx Special saloon in similar circumstances. Increased speed over that of a normal Dauphine introduces sudden and severe oversteer (normal Michelin tyres were fitted). Fuel consumption, driving normally, is 31 m.p.g., compared with the figure of 45.1 m.p.g. which Motor Sport obtained from the standard Dauphine road-tested in May, 1956. Acceleration cheeks gave the following figures:—

It was impossible to reach 70 m.p.h. from a standstill in the straight ¼-mile at our disposal.