Renault Dauphine
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DEVELOPING A SALOON CAR ENGINE
By Ray Dilley
A visit to K. N. RUDD (Engineers), Ltd., is like a Sunday afternoon treat. At their showrooms in High-street, Worthing, you can feast your eyes on the cream of British and Continental high-speed cars.
Few automobile distributors offer such a glittering array of the elite, yet this organisation have not forgotten the family man, the man who wants high-speed motoring at low cost. To satisfy this demand,Ken Rudd has gone to work on the Renault Dauphine.
It is easy enough to "soup up" a standard saloon. Shave the cylinder head; fit four-branch exhaust and two S.U. carburettors, and you're there. At least, you might think you're there. But you could find that the engine is hard to start, and bumpy in the rev. range. And the petrol consumption is liable to become heavy. To do the job properly three essentials are required: time, equipment, and skilled engineers. Rudd's have them all.
THREE-FOLD
They started back work on Renaults in 1955, and their aim with the Dauphine was three-fold—they set out to increase the brake-horse-power of the engine throughout the entire rev. range, they wanted to keep the petrol consumption the same as on the standard model when driven under normal conditions, and they meant to improve the road-holding qualities as required for extra speed.
The first steps in the development of the engine entailed slightly increasing the compression ratio from 7.8 to 8.3, enlarging the inlet valve size, balancing the combustion chambers and fitting anti-surge double valve springs. But the real secret of the power lies in the design of the camshaft. Rudd's have designed their own. The engine modification also includes a twin-inlet four-branch manifold, with straight - through silencer, twin S.U. carburettors, and air cleaners.
The only real way to assess the power in an engine is to place it on a dynamometer which measures the actual brake horse-power. The following chart illustrate how the brake horse-power of the Dauphine engine has been developed, and covers the complete rev. range.
At 4,000 revs. an extra eight brake horse-power is obtained.
Standard Model Ruddspeed
Revs. B.H.P. Revs. B.H.P.
2,000 15 1/2 2,000 16
2,500 19 1/2 2,500 20 1/2
3,000 23 3,000 26
3,500 24 1/2 3,500 31
4,000 27 4,000 35
4,200 30 4,200 38
5,000 42
My first thought after hearing about these engine modifications went to the factory guarantee. Was it still applicable with the Rudd modifications? Although the Dauphine in its standard form is seldom ever the subject of a guarantee claim,Renault will not expand their guarantee to cover modified vehicles.
RESPONSIBILITY
Rudd's will, however, accept the responsibilities of a manufacturer's warranty under the same terms and conditions, providing the vehicle is supplied by them and the tuning kit fitted in their own workshops. The modifications to the suspension concerns the rear suspension only which has been lowered. It gives the rear wheels a negative camber which helps to overcome the over-steer tendencies I experienced when cornering in a standard model. When I tested the standard model recently I was extremely impressed with it’s road-holding capabilities. But the Ruddspeed modifications to the rear suspension improves it even further, and makes controlled drifting through corners very easy. One of my few criticisms of the standard Dauphine was that it was fitted with a three-speed gearbox. The engine modifications by Rudd completely remove any doubts I had in that direction.
Acceleration is very brisk, and I still don't know speed what the top speed is! The speedometer is marked up to 75 miles per hour, but the needle had far passed this mark, and was dipping down into the wave gauge! I gave Dauphine two speed testa. The 0 to 60 miles per hour from a standing start was accomplished in 17 seconds, an incredible time for such a small engine. I tried a measured quarter-mile from a standing start and came up with very creditable 22 seconds.
SHOPPING CAR
Back the town after these sprightly road, moments on the open the Dauphine lost its Grand Prix exhaust bark. Once more it assumed the guise of a shopping car with no lumpiness in the carburation and a second gear capable of idling at 10 miles per hour. It all adds up to one of the few really successful developments of a standard saloon engine that have I had the pleasure to test. How much extra does all this cost? A standard saloon three-speed gearbox priced £689, and Ruddspeed form, €747. Optional four-speed gearbox model in standard form is £699, or in Ruddspeed trim £757.