Rotary Valves and Formula II
I am sure I share the desires of many of your readers to see a British engine show a clear-cut lead in Formula II racing. We have the drivers and the chassis, but as regards engines we appear to struggle along following the lead of others.
My armchair ruminations lead me to the conclusion that the greatest single factor to be considered in Formula II engine design is efficient breathing. To attain this we see short-stroke engines being used together with other devices to make room for the largest possible poppet valves regardless of the formidable mechanical problems of operating these valves, and it seems probable that Ferrari have already arrived very close to the most efficient breathing from poppet valves. So what is to come next ? To beat Ferrari we need to break away from convention and abandon the poppet valve for the only more efficient type of valve which is suitable for racing - the rotary valve.
I have no reference books to hand, but didn't the Aspin conical rotary valve give tremendous results in a motor-cycle engine about fifteen years ago? There was also the Cross rotary valve and, looking farther back, I know an Edwardian car had rotary valves. (Itala - Ed.)
Rotary valves have several inherent advantages: (a) there is almost no restriction on the size of the port, particularly if a single port for inlet and exhaust is used; (b) the port is unobstructed by the valve head and guide; (e) there are no reciprocating parts.
The difficulty with rotary valves is to ensure gas-tightness without risking seizure. This is, no doubt, a very formidable problem but it is a matter of engineering rather than of design, and very much the type of difficulty that the pioneers of British racing cars have had to face in the past whenever a real advance has been in sight. For instance, when very high revs were sought as a means of increasing power the resulting bearing troubles were eventually overcome in the workshops. Again, supercharging brought with it a host of troubles to which mechanics have provided the answers.
Let us start a campaign for rotary valves in British Formula II cars.
I am, Yours, etc.,
A. F. CARLISLE, S/Ldr.