keethrax wrote:16vCorey wrote:Now if they'd just actuate valves with electronic actuators instead of camshafts we'd have infinitely variable valve timing and no parasitic drag of (sometimes multiple) camshafts. It seems like it would be easy enough to keep them in time with a crank sensor. Just have a fail safe that would immediately close the valves if there was a problem and you wouldn't have to worry about interference engine issues.
I have a sneaking suspicion (but no solid evidence or specific knowledge) that electronic actuators with a sufficient mtbf under the conditions they'd be operating at would be too pricey to be worth it. But I'd love to be wrong on that, because if I am, there's all kinds of cool E36 M3 you could do.
I looked into it at one point. here are the issues:
Opening speed is dependent upon temperature and can't be done in stages (example, it you had an infinitely fast, infinitely positionable actuator, you could draw the absolute best cam profile for the valve seat - super quick opening and tapering closing) and the actuators wear out giving slower reactions. Current high grade solenoids are rated for X cycles which turned out to be something like a few hours/days of run time.
They are absolute power hogs
They heat up like mad, adding to the other issues
They are actually not that strong unless you go big.
