Those GP Opels

Sir,

I was very interested in Mr. Corner’s letter in your November issue about the 1914 G.P. Opels, in which he raises a query about the maximum speed of Mr. Phillip Mann’s 1914 G.P. Mercedes.

The engine of this car has four separate cylinders of a fabricated type, using a forged steel barrel and head and fitted with welded on sheet metal water jacketing. Before I commenced the rebuilding of this engine these cylinders, which were in a very worn

state, and being too thin in the walls for a normal reboring process, had been sleeved by another firm and been bored to yo mm. I had new pistons made to the original type, but to suit the new bore size. Inspection of the interior of the engine revealed that at some time in its life a connecting rod had failed.

Mr. Mann has in consequence not felt inclined to stress this engine to its maximum. Furthermore in consideration of the bore size now being 90 mm. instead of its original size of 93 mm., it is unlikely to conform to its 1914 speed.

I would like to point out that the 1914 G.P. engine is very similar in many respects to the Mercedes Aero engine of World War I. Drawings and photographs of this engine enabled many questionable points to be cleared up during the rebuild of the G.P. engine.

Sutton JOHN BLAND