Variable Valve timing.

[Series8217]

If it ends up being too hard to package the concentric cam in there, there's always this: https://www.youtube.com/watch?v=Bch5B23_pu0

[ericjon262]

Didn't say it wasn't possible... just a manufacturing challenge. There's nothing in the design of the concentric cam that can't be made by a decent machine shop.

Getting the movable lobes ground may be challenging.

Had any thoughts about how to control the two-axis setup?

The photos I've seen of the Viper setup seem to indicate that the phasors are sort of nested, so you may have to go all the way to buying the Viper parts in order to have something that works well.

I was thinking about this earlier, why not grind the lobes after the cam is assembled, and then take it back apart and clean it?

as far as the phaser goes,



this was on Mechdynes home page. something like that would work fine. then you just need a PWM valve to control both circuits. you would have to use the windows without vanes for one channel(of coarse by installing vanes), and the one with the vanes for the other. I don't see why it wouldn't work.

My only concern is what happens to "cold starts", where oil pressure has bled off, and there's no pressure to tell the cam where to be? how would it default? there would need to be something in place to make it default at 0PSi, maybe some kind of spring setup?

[ericjon262]

If it ends up being too hard to package the concentric cam in there, there's always this: https://www.youtube.com/watch?v=Bch5B23_pu0

Seen this before, very cool, very complicated, I'd love to do it, but I don't see it as feasible, or at least, not as feasible as concentric cams.

[The Dark Side of Will]

I was thinking about this earlier, why not grind the lobes after the cam is assembled, and then take it back apart and clean it?

As long as you have a fixture to maintain the outer and inner in a known orientation, then you could do that.

as far as the phaser goes,

this was on Mechdynes home page. something like that would work fine. then you just need a PWM valve to control both circuits. you would have to use the windows without vanes for one channel(of coarse by installing vanes), and the one with the vanes for the other. I don't see why it wouldn't work.

My only concern is what happens to "cold starts", where oil pressure has bled off, and there's no pressure to tell the cam where to be? how would it default? there would need to be something in place to make it default at 0PSi, maybe some kind of spring setup?

Get into the detailed mechanical design and you'll probably find it's not all that simple. Good luck!
The lobes will default to the most retarded position on cold start, until the oil pressure builds up to move them to a commanded position.

[ericjon262]

I was thinking about this earlier, why not grind the lobes after the cam is assembled, and then take it back apart and clean it?

As long as you have a fixture to maintain the outer and inner in a known orientation, then you could do that.

as far as the phaser goes,

this was on Mechdynes home page. something like that would work fine. then you just need a PWM valve to control both circuits. you would have to use the windows without vanes for one channel(of coarse by installing vanes), and the one with the vanes for the other. I don't see why it wouldn't work.

My only concern is what happens to "cold starts", where oil pressure has bled off, and there's no pressure to tell the cam where to be? how would it default? there would need to be something in place to make it default at 0PSi, maybe some kind of spring setup?

Get into the detailed mechanical design and you'll probably find it's not all that simple. Good luck!
The lobes will default to the most retarded position on cold start, until the oil pressure builds up to move them to a commanded position.

yeah, I don't think the spring idea was a good one at all, I wasn't thinking when I said that. Maybe some kind of oil accumulator the pressurizes the system during fuel pump prime?

[The Dark Side of Will]

All the OE systems end up fully retarded on a cold start. You just have to make sure your PTV clearance is adequate with the cam fully retarded. The computer will be able to command it within about 2 seconds of achieving idle RPM anyway.

[ericjon262]

All the OE systems end up fully retarded on a cold start. You just have to make sure your PTV clearance is adequate with the cam fully retarded. The computer will be able to command it within about 2 seconds of achieving idle RPM anyway.

so in other words, I'm way overthinking this aspect of the swap...

[The Dark Side of Will]

Yeah, it's a non-issue as long as the piston-to-valve clearance is ok.

You are aware that each phaseable cam has to have its own position sensor, right?

[ericjon262]

Yeah, it's a non-issue as long as the piston-to-valve clearance is ok.

You are aware that each phaseable cam has to have its own position sensor, right?

yes, I am aware, I was thinking about modding a timing cover to accept one.

another idea would be to mod the oil pump drive, as it is just a distributor with the top half cut off.

[The Dark Side of Will]

If it ends up being too hard to package the concentric cam in there, there's always this: https://www.youtube.com/watch?v=Bch5B23_pu0

Continuously variable valving (My term: CV2) has been the holy grail of the internal combustion engine for a long time...

That's the first time I think I've heard of the possibility of using CV2 to turn the engine into an air pump to enable some sort of regenerative braking.

I'd been thinking for a while that solenoids controlling air pressure could be used as a CV2 mechanism, but the pressurized air needs to be blown down at some point in order to allow the valve to reciprocate. That ends up being pretty noisy, although not as noisy as the exhaust blow-down stroke.

[Series8217]

But valve train noise is cool.