The cam lobes are separate from the camshaft, and are mounted on a camming mechanism that alters their rotational speed as the lobe sweeps across the rocker.
Change your oil often, people!
The cam lobes are separate from the camshaft, and are mounted on a camming mechanism that alters their rotational speed as the lobe sweeps across the rocker.
Change your oil often, people!
Engineers are really pushing the limits of the internal combustion engine!
Hyundai?!?!?!!?!?
Think of the billable hours that's going to generate...
He's not exactly right. Every added component adds another item to fail which in turn increases the possibility of failure. That said, new car reliability can be downright incredible.
I have a Franco Automatic Timing Gear on my 924:
https://www.vwvortex.com/threads/franco-cam-gear-dyno.2546872/
Its a poor man's VVT/VTEC. Works better when you have distributorless ignition or at least the ability to control the ignition curve of the distributor that is usually connected to the end of the camshaft.
Nothing new under the sun, just lots of wonderful optimization.
I like it
In reply to Stefan (Forum Supporter) :
That's variable valve timing, not variable lift or variable duration. Three completely different concepts.
This is the world's first infinitely variable duration setup. Every other system that had been used had multiple cam lobes, so there could only be two discrete durations.
carguy123 said:Hyundai?!?!?!!?!?
30 years on, their ad campaign is appropriate.
In reply to Pete. (l33t FS) :
WRT the oil, the supply I see are pretty large- much more robust than other cam technology I've worked on- where oil faults were a real big deal. And given that it's mostly a cam based system, it will probably be very reliable. Still pretty complicated, but I've seen worse.
That would very much force an interesting method to calculate air mass- and then how it's optimized will take some time. But for 5% FE, not sure the value is really there, and 5% vs what? 5% vs. base, vs VCT, vs VTEC, vs VVL, vs any combination- which one of those is it 5% better than?
(and the note that current valve systems are not optimized for all speeds/loads is not quite accurate- VCT is optimized for all speeds and loads, and the VVL system that BMW uses is also optimized over the entire map. Only VTEC is really a two position switch these days)
Interesting.
BTW, there are other valve actuation systems coming in the very near future. ICE's will be around for quite a while longer- even in the face of some VERY tight emission rules coming.
Why do this when FreeValve exists?
STM317 said:Why do this when FreeValve exists?
Cost and reliability. The technology that the FreeValve system uses has been around for a long time now- much longer that Hyundai's claim of 9 years for this. And it's still not been applied to a large production engine. For sure, it's not because people don't like that concept- everyone knows that's the most flexible cam timing out there. It's the gold standard WRT what it can do.
It's just not ready, like fusion power plants.
In reply to alfadriver :
My ass-umption about Hyundai's claims was in comparison to a 2019 model that ONLY had variable cam timing and direct injection.
F1 has had pneumatic valve actuation since 1985 but using that technology to allow flexible timing variability has been banned, ostensibly to prevent potentially huge development costs.
OTOH, I'm not sure how an infintely variable VVT system would work for long on things like pickup trucks that got an oil change with every third owner, so maybe higher and higher tech isn't a real world necessity.
In reply to wspohn :
F1 has had pneumatic valve springs for a long time, because valve springs are remarkably difficult to do reliably, but the valves have always been opened by lobes on a camshaft.
Isn't the Fiat Multiair a hydraulic fully variable lift and duration system?
Infinitely variable? No thanks. What happens when a mechanical failure hangs a valve open too long?
Opti said:Infinitely variable? No thanks. What happens when a mechanical failure hangs a valve open too long?
It should be called continuously variable, since there's not infinite range. For sure, the range is limited to not hit anything.
In reply to alfadriver :
I would hope so but im skeptical. Ive seen plenty of incredibly obvious dumb things on modern cars.
It seems a mechanical stop to limit travel, even during a failure, or valve reliefs (maybe) could do the trick, but im sure there are interference engines out there that wouldnt be if it the manufacture spent 10 more cents a piston to have valve reliefs.
Opti said:In reply to alfadriver :
I would hope so but im skeptical. Ive seen plenty of incredibly obvious dumb things on modern cars.
Out there somewhere, there is an engineer who would climb over a mountain of virgins to screw one mechanic.
Opti said:In reply to alfadriver :
I would hope so but im skeptical. Ive seen plenty of incredibly obvious dumb things on modern cars.
It seems a mechanical stop to limit travel, even during a failure, or valve reliefs (maybe) could do the trick, but im sure there are interference engines out there that wouldnt be if it the manufacture spent 10 more cents a piston to have valve reliefs.
My bad on saying infinitely instead of continuously. (I mean, there are an infinite number of numbers between 0 and 1...)
If you check out the mechanism, there is a maybe +-20 degree window of operation. I haven't stuck a protractor on my monitor to check that figure 
But the design makes "coming apart" about as likely as a variable camshaft position hub "coming apart". Technically possible, but enough other things would have to fail to allow it to happen that the engine will be a smoking crater for other reasons before it gets to that point.
Last I checked, the word was that there has been not one failure of the VTEC system in the wild. Talk about mind blown... I wonder if that statement is still true. And I wonder if this setup will be able to claim the same thing.
alfadriver said:STM317 said:Why do this when FreeValve exists?
Cost and reliability. The technology that the FreeValve system uses has been around for a long time now- much longer that Hyundai's claim of 9 years for this. And it's still not been applied to a large production engine. For sure, it's not because people don't like that concept- everyone knows that's the most flexible cam timing out there. It's the gold standard WRT what it can do.
It's just not ready, like fusion power plants.
This system seems like it could also have some negative cost/reliability aspects to it doesn't it?
I guess what I'm wondering is how much time/money have been spent by various OEMs in the last 15 years on various alternative technologies like this? And how advanced might something like FreeValve tech be if the same resources had been put into it instead.
In reply to STM317 :
15 years ago, everyone was working on a free valve kind of technology. And by everyone, I mean everyone. So it's not as if it was not worked on- which I'm sure spurred the various alternatives we see now.
There are certain parts of electronically controlled valves that just can't get much cheaper, or easier to run. The biggest take away- moving the valves electrically vs. a cam is not even close to the same effort. Cams are much easier to deal with.
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