[Excaliber]

Some engines, like BMW, are turning 22,000 rpm, but with a shift point closer to 20,500 for more reliability. They still use a classic camshaft, but have NO VALVE SPRINGS! Somehow they use pneumatic pressure in place of a valve spring, or electro mechanical (magnetic?) of some nature. I've never seen a picture and would sure LIKE to see how this "pressure" is applied to the valve in lieu of a spring.

At this rpm (20K plus) the limiting factor is the fuel BURN RATE! The flame travel is to slow. Another limiting factor is friction and mass. Diminishing returns as the rpm goes up because it takes more horse power to overcome the friction, so you get a catch 22.

Fuel additives are being experimented with to speed up the burn but more importantly to reduce friction on the top piston ring.

I've heard of idle speeds in the 4000-5000 rpm range. One of the issues with these engines is the "explosion" of power at a certain rpm range making the vehicle difficult to control. An engine with less power but a flatter torque/horse power curve allows for more drive control. Some teams are taking this approach and it seems the F1 engine "wars" are less about ultimate horse power and more about controlling the output.

This IS a fascinating subject and difficult to get specific information on. I'm not sure WHY that is, perhaps the engine guys are hiding it?

There are some "camless" engines that use electro\mechanical valve actuators. That may be banned in the future. Camless engines, the next generation piston engine?