So, since most motors now are computer controlled, why don't they have solenoid activated valves? It would be way better then VTEC or any other VVT method, since it wouldn't be limited to a few choices, the computer could modify the valve timings to an infinite degree. If you used 4 valves per cylinder, then having a solenoid go bad shouldnt cause too much damage, unless maybe its stuck in the open position?
They are moving in that direction. Once a 42 volt system makes its way into cars solenoid controled valves should soon follow. It will be great to get 40mpg or better then goto the race track and press a button on the dash and run the 1/4mile in 12-13 seconds.
Where have you been? Solenoid activated valves have been in development for years. I wouldn't be surprised if we see them in engines in the next 10 years.
Mercedes has been working on this for some time. Do a google search for "Active Valve Train"
Honda Accord has had VTEC for some time now. My 98 4 cyl has it..and what a fine car it is. It is standard, with the 4cylinder, about 18,000 bucks!
Yeah but why haven't we seen any practical applications already, even in high end motors we should be seeing SOMETHING....
They've been spending the last 10 years making sure that the solenoids will last 10 years. ;-)
What can I say, Honda's wierd, so are the kids who drive them and think VTEC adds like 50 HP.. "omg my civic will smoke your chevy once the VTEC kicks in!"
cool..
:D its better then my ISP's new server.
I think the problem at this point is the system would use too much power for the electrical system to supply. Once they move to 42-volt systems it might be more feasible..
Perhaps this is slightly off topic but I'll toss this one out anyway......
I have been driving now for 50 years. I have owned German, Jap, and American cars.
Both GM and Ford engines are primarly OHV rather than OHC engines. Having owned a wide range of cars over the years I have never seen the slightest advantage to the average driver between a OHV and OHC engines.
I assume a OHC engine is more complex and costly to make and repair so why does does say the Japs primarly make OHC engines and GM and Ford primarly OHV engines?
I understand the theoretical advantages for a OHC engine but in my experience I have never seen any real practical advantage in day to day driving.
Any thoughts on this?
As the demand for increased fuel economy and lower emissions builds, yet consumers are loath to drive under-powered vehicles, many manufacturers (the Japanese in specific) have turned to using smaller displacement engines with some sort of mechanism (TVIS on older Toyotas, VTEC on newer Hondas, et al) to extend the engine's breathing capability up to higher revs. The goal is to provide an economical engine it cruise, yet one that can build power through revs when necessary. A pushrod motor will have reliability issues (at least in cost-critical mass production environments) if forced to operate above 5000 rpm on a regular basis, not to mention the complexity/packaging problems that would be involved if a VTEC-style system were to be implemented with a central cam location (could you imagine trying to package 24 lifters in a small block's valley?)
As for solenoid-activated valves, I would guess their absence > Perhaps this is slightly off topic but I'll toss this one out
the electrical power required for solenoids would need wires larger than even spark plug wires to work, and then charging systems would not be able to meet the demand, even 42-volt systems. a breakthrough in solenoid technology would be required to open up this possibility.
pneumatics are not reliable enough over the entire -45 to +45 C temperatures that cars must tolerate.
it's not a huge secret that the automotive industry is working hard on an electro-hydraulic valve actuation solution. perhaps cadillac will be the first to put one in production. i think the big hurdle right now is trying to get the system working up to the 6000+ rpm redline reliably.
as a side-note, the most sophisticated race engines which are found in formula1, use a pneumatic valvetrain, but the pneumatic part only replaces otherwise metal coil valve springs. they still use solid cams and cam-phasing, but talks of infinite variability through solenoids is only rumour. it isn't easy getting things to work well at 19000+ rpm. irl motors are pushrod, solid cams & springs. cart motors are dohc, solid cams & springs.
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