Thread: DUNSTAN ROTARY VALVE HEADS

And here is another one. The crappy photo attaching system will only allow five per post.

Ive often wondered why rotary valves etc are not used on 4-strokes.

Originally Posted by Slunnie

Ive often wondered why rotary valves etc are not used on 4-strokes.

Sealing and combustion temps, although you'd think in this day and age with carbon and ceramics it could be overcome, so there must be some other reasons why too.

I know it has been tried again in the last few years for some potential F1 engine projects but nothing so far that I'm aware of has come of it.

Originally Posted by rick130

Sealing and combustion temps, although you'd think in this day and age with carbon and ceramics it could be overcome, so there must be some other reasons why too.

I know it has been tried again in the last few years for some potential F1 engine projects but nothing so far that I'm aware of has come of it.

Sealing, cooling, and lubrication were the triple Achilles heels of this design. Some had a hollow rotor which was water cooled.

Originally Posted by rick130

Sealing and combustion temps, although you'd think in this day and age with carbon and ceramics it could be overcome, so there must be some other reasons why too.

I know it has been tried again in the last few years for some potential F1 engine projects but nothing so far that I'm aware of has come of it.

As with many "new ideas" the poppet valve performs so well that it is difficult for a new technique that does not have a century of development to compete. Poppet valves have come a long way - I remember reading recently a detailed account of the first flight from UK to Australia in 1919 - one of the routine jobs every night was to do a valve grind, quite often needing replacement valves and/or springs. With two twelve cylinder engines, and with non-detachable heads, quite a job. For comparison, today, many engines see out their lives without the valves being touched.

John