Electronic valves istead of cam!

[danielsatur]

No belts, chains, gears, push rods, hydraulic lifters, cam, cam followers, and
tensioners.

Positive - Less wear + tear ,weight

[vgames33]

It would also allow for infinitely variable lift, timing, duration, etc.

I think BMW made a prototype a few years ago. I'd imagine there are reliability issues of some sort, otherwise someone would be making engines like that by now.

[Moppie]

Running prototypes have been made, the problem is operating them fast enough to run an engine at high enough revs to make any power, and being able to operate large enough valves to run an engine large enough to make any power.

If you weigh a valve, then measure how fast it moves as it opens and closes at 5,000rpm, you discover some extremely high G forces.

[shorod]

Conceptually these would be similar to the DCCV valves on the Lincoln LS. Danielsatur, you've complained about these DCCV units in the LS forum, would you really want such a beast in such a critical role in an expensive engine?

Rail guns are getting impressive enough now that it's probably not too unreasonable to think solenoids will be small enough, powerful enough, fast enough, and reliable enough to run valves of decent size soon. Just like with timing belts, the manufacturers could have a recommended replacement interval for the solenoids. And if they made them accessible enough, the price to change 24-48 solenoids may not be all that much different than the price to replace a timing belt(s).

-Rod

[danielsatur]

How about the rotary engines next step?
Very few engine parts, and 200k+ miles without any planned obsolescence.

Got to go, because doing a $600 timing belt on a 4-cylinder interference motor today, or a new engine.

[shorod]

They'll need to figure out how to get the efficiency of the rotary up before that becomes a viable solution. Modern rotary engines don't seem to do very well when it comes to fuel economy, and auto manufacturers are feeling continued pressure to increase corporate fuel economy. That is probably higher on their list of priorities than reducing operating costs for the consumer.

-Rod

[danielsatur]

If Mazda RX8 got rid of the four doors and keep the sports car reliability, I wouldn't worrie about the fuel.

Ford did that with the T-bird years ago, and lost to the GM's corvette.

[grider]

bmw did build several versions of this engine and one was very solid and depenable(lots of small valves) but they couldnt get the power they needed to put it into production who cares if it dosnt need a t belt if it wont go its worthless in the ultimate driving machine in the end the cost of building the engine verses the output just didnt add up to profit

[la1]

are desmodromic valves worth discussing or are they a technology of the past.

[Moppie]

Originally Posted by la1

are desmodromic valves worth discussing or are they a technology of the past.

I do remember someone mentioning something about them in the past.
Are they the rotating ball valves?

[la1]

No, one rocker arm opens, another rocker arm closes the valve...no valve springs. I have only seen it implemented on pushrod engines. I think it was to eliminate valve float...perhaps now adays with overhead cams, electronic everything ..and engines that can sustain much much higher revs...possibly desmo valves are a thing of the past...then again what is old is new again.

[Moppie]

Originally Posted by la1

No, one rocker arm opens, another rocker arm closes the valve...no valve springs. I have only seen it implemented on pushrod engines. I think it was to eliminate valve float...perhaps now adays with overhead cams, electronic everything ..and engines that can sustain much much higher revs...possibly desmo valves are a thing of the past...then again what is old is new again.

Ahh, ok, so you basically push the valve closed, rather than letting a spring control it.

I can't see it saving anything in terms of weight, rotating mass, or improving valve control.