From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Engine design, moment of inertia, and a potential V8 engine, with comparisons to a Packard.
| Identifier | ExFiles\Box 43\4\ Scan319 | |
| Date | 9th December 1926 | |
| Oy3-E/12926 -3- December 9, 1926 The engine weight being grouped more nearly over the axle would tend towards a greater moment of inertia of the complete car, and therefore better riding for a given spring deflection. (See my note to R.{Sir Henry Royce} of November 10th on inertia tests.) We think that a basic defect of the long car is its "inadequate" moment of inertia. What this would amount to is a slightly enlarged version of the 20 hp. with nearly twice the available horsepower in about the same length of bonnet, and about 5" more body space from the dash to the rear axle. It appears to me that the major difficulty is to get overhead Phantom valve gear in a reasonable width of bonnet. Overhead tappet adjustment like the Phantom is particularly useful on the V eight because of accessibility, besides all its other advantages. With say 5" stroke it seems as though the bonnet width at the front of the engine would have to be 30", or the full width of the frame, unless we could "steal" from the length of the valve guides. [Handwritten note: investigate whether this is possible] Would it not be worth while to challenge Elliott to design an intrinsically balanced 8 cylinder Vee engine with 60° between the cylinders instead of 90°? (I have recently found that the Packard 8 from front axle to dash is 5" shorter than the 40/50. It is also a much smaller engine, 358 cu.ins. compared with 468 cu. ins. The Packard also carries its radiator further forward over the axle than we do. This tends to improve the moment of inertia and may be worth considering.) Yours very truly, MO/E Maurice Olley | ||