Omni Valves?

[Pinhead]

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Omni Valves
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Omni Valves

An engine’s "sweet spot" or efficient torque zone occurs when the inertia of the escaping exhaust gas creates low pressure in the cylinder assisting intake into the cylinder. So camshafts are designed to open the intake valves while the exhaust valve is still open (valve overlap) and the piston is still moving up in the exhaust cycle. This Valve overlap is helpful at certain RPMs but is harmful at low RPMs because of reversion (exhaust gases contaminating the intake mixture).

OmniValves work to create uniform volumetric efficiency at low RPMs. OmniValves sense the cylinder pressure and open or close in a controlled manner to eliminate reversion. OmniValves fluctuate as needed in your low RPM range (300 RPM and up) when your intake and exhaust manifolds are inefficient. As the manifolds come into the efficient range OmniValves operate as normal valves. Initial Dyno testing also indicates that OmniValves again enhance performance as the manifolds become inefficient at higher RPMs. HP and Torque are maintained longer than without OmniValves.

The jest of it, is they combine the principals of a reed valve with that of a poppet valve. Has anyone had any personal experience with them? Would anyone like to try them? (they will give a set of valves to someone that would do some unbiased testing). HINT HINT

[Pinhead]

No comments? They seem like the perfect solution for street/strip motors that require a big, fat torque line.

[rookie]

Looks like a crutch for a bad combustion chamber design like the one shown on their site.
I wonder if he would see the same results if he started with a good combo?

To big and heavy for performace, looks like one more moving part to break and in the worst place.

[1989GTA]

They look awfull heavy. I don't think they would rev up very high. Maybe in a low rpm motor they might have some merit.

[84Dave]

They work absolutely wonderful in a flat-6 Continental Experimental aircraft engine. They're too heavy for any kind of rpm in an automobile engine. Dave

[Pinhead]

They were tested in some Harley Davidson motorcycle engines and easily supassed 9,000 rpm without trouble...

[MAP]

Greetings,

My guess from looking at the website photos is that the OD of the valve that would contact the valveseat in the head, is made as an axially floating ring, with an ID bore of some 70% or so of the full valve diamter, which rides for as much as a 0.16"-long range along the OD of a corresponding cylindrical portion of the rest of the valve.

Presumably, when pressure in the port is higher than in the CC, the ring is bottomed against the full-diameter portion of the valve proper, and it functions as a "regular" valve.

When the pressure in the CC is higher than the port, then the ring slides upward along its ID bore and stays seated on the head, until and unless the valve lift exceeds the 0.16" axial travel limit of that ring.

With 0.16" of ring axial travel, I would basically call this a low-lift mechanical diode. Or better, a Zener diode.

If I've got that right, then this somewhat reminds me of the Belleville-washer arrangement inside shock absorbers to achieve divergent valving, so as to get the best of two worlds: first, low dampening at low stroke velocities, for good car NVH over small bumps, and second, high dampening at high stroke velocities, for good large-signal suspension control.

But as for this Omni valve, I see some advantages and disadvantages:

1.) Higher total valve mass, as has been noted previously.
2.) Extra sealing surfaces mean more potential paths for valve leakage as well as potential for wear along sliding surfaces.
3.) The floating ring action, contrary to the website claim, cannot have an instantaneous response, since it has finite inertia.
4.) At very high engine speeds, and precisely because of the ring's inertia, it will create its own float phenomenon, independently, and in conjunction with, the valve's overall "floating" propensity.
5.) If the centroid of the pressure difference across the ring isn't coaxial with the valve, then the ring might have a tendency to "cam-jam" in its axial travel.
6.) Since the stiffness presented to the ring by any reasonable pressure difference is likely to be rather low compared to the ring's mass, and because the ring's collision with the rest of the valve as well as the valveseat would be highly elastic, then its motion could become quasi-oscillatory with a frequency that may not be harmonically related to engine speed. This could be problematic.
7.) I would imagine that the ring motion relative to the valve would keep all translating/sealing surfaces free of carbon and sludge accumulation, but has this proven to be true?
8.) Is it necessarily true that best engine function is always achieved when the pressure in the intake port is higher than in the CC? (I suspect at higher engine speeds at least, that this may not be true, where the exploitation of wave-like phenomena in the intake tract may boost VE.)


Best,
Mark

[Cammer]

OmniValves promised much, delivered little!

[Devious]

Originally Posted by Cammer

OmniValves promised much, delivered little!

Does this mean that you have direct experience with this product?

[MAP]

Hi Folks,

In thinking about this a bit further, in theory at least, it's clear that the concept could yield some big gains at the bottom end, and especially under a part-throttle condition. Economy and emissions seem like they could be big beneficiaries here. Most specifically, one could imagine running tighter LSA's at the camshaft for higher peak torque, with much less low-speed disadvantage of overlap losses, for given I and E durations. In short, the torque bandwidth of the motor ought to increase substantially.

But at higher speeds, it seems a bit chancy to rely solely on pressure differences and ring inertia to control matters, because I think that control could get rather erratic. Too bad there isn't a more positive means of "locking" the ring to the rest of the valve under such circumstances.

Also, there's no question that the valves shown on the website are heavy. The thickness of the part of the valve that seals with the underside of the ring seems excessive. I wonder how thoroughly these valves have been engineered?

And again, the initial impression is that data is rather scarce - can someone provide more information?

Best,
Mark