Quote:
Originally Posted by Joeggernaut
Nissan and Toyota do use higher rpm engines though. BMW systems are groundbreaking but they are never simple like the Japanese who later improve upon their ideas.
What do you think about electromagnetic controlled valves (magnetic actuators)? I think it is feasible and could completely eliminate the mechanical linkage (camshaft/springs/etc). The ECU would only then have to control the electric pulses. The only downside I see is what happens if the engine loses electric power then you might run into bent valves as they might not return to their previous position. I guess you could use capacitors to store enough energy to limp the car to a complete stop while still having valve movement.
EDIT: Here is a cool little article that someone combined sources from into one answer: Working of camless engine with electromechanical valve actuator
Then all we would need is magnetic bearings for the crankshaft and we could almost eliminate the need for oil except for piston lubrication. |
Not really. Nissan VQ37s hit 7500rpm but they seem to have very high oil temperature when run at high speed (and their specific torque isn't all that great at the top end) suggesting there is some serious friction going on. No Toyota Valvematic engine runs over 7000rpm.
Camless valve actuation sounds nifty but yes, bent valves when power is lost is a problem.