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The Vanwall Grand Prix engines
Part 3: Technical anomalies


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Peter Collins


Vanwall Special




25th Italian GP (September 5, 1954)

Peter Collins, Vanwall Special, 1954 Italian GP

In researching this article, it became clear that there are three aspects of the design and origin of the Vanwall 2-litre/2.3-litre engines which have been incorrectly commented on by various motoring writers over the years.

This writer is grateful to Derek Taulbut BSc (Eng.) Hons, DMS (author of the very informative website Grand Prix Engine Development 1906-2000), Stuart Reid of the Austin Champ Owners' Club and Sharron Bland of the Rolls-Royce Enthusiasts Club for the assistance and information they gave which hopefully now enables the correct details to be documented.

The matters in question are:

3.1 Valve Included Angle

Numerous writers have stated that the 2-litre Vanwall engine had a VIA of 77°, the same as the experimental water-cooled BRM/Norton “500” single of 1949. This is incorrect.

The 2-litre Vanwall engine was designed with a VIA of 64°, the same as the contemporary works Norton “500” on which it was based and the 2.3-litre engine used essentially the same cylinder head. The VIA of the final 2.5-litre Vanwall was reduced to 60°.

3.2 Number of Crankshaft Main Bearings in the Vanwall

Until the publication of Denis Jenkinson's and Cyril Posthumus' book in 1975 (for which they had access to the factory racing records), all reference to the 2-litre Vanwall spoke of it as having a 5 main bearing crankshaft.

But in this book the authors stated that the 2-litre engine had a 4 main bearing crankshaft and this was repeated by Edward Eves in Autocar magazine of 22-01-77, in which he too wrote of a 4 main bearing crankshaft (with a flying middle throw). Given the depth of technical detail in Eves' article, he had access to the racing records too, for VP Ltd. - GKN subsequently issued this article, as an official publication on the Vanwall titled Vandervell The Spell Breaker (Eves states the crankshaft was forged by Smith's Stamping Works of Coventry whereas DSJ & CP state it was forged by the associated firm of Smith-Clayton Forge in Lincoln). This writer has postulated on the possible thinking behind the adoption of this unusual crankshaft configuration, in part 1.1.

The 2.3-litre engine used the same crankshaft as in the 2-litre engine and it was in the 2.5-litre engine that a 5 main bearing crankshaft was adopted, which was forged by the Smith-Clayton Forge “arm” in Lincoln.

3.3 Number of Crankshaft Main Bearings in the B40 Engine

In the above-mentioned publications and also in a December 1983 Classic & Sportscar magazine article by Posthumus it was stated that the Rolls-Royce B40 crankcase/cylinder block used as a basis for the 2-litre Vanwall engine had only four main bearings. This is incorrect.

The writer felt these statements were questionable, as the other engines in this Rolls-Royce family of B-series military engines all had a crankshaft main bearing either side of each big-end and the intention of Rolls-Royce was to have a commonality in design.

After checking with the reliable sources mentioned in the beginning of this section and studying a long section of the B40 engine, it is clear that the B40 had five main bearings, not four as claimed.

The crankcases used for the basis of the 2-litre and 2.3-litre Vanwalls were extensively modified from the source B40 case, with the middle main bearing support omitted. As detailed in parts 3.2 and 4, the 2.5-litre Vanwall crankcase had five main bearings as in the source RR B40 and new crankcase castings were made and this was documented by DSJ & CP in their book.