Reed valve in intake = 'infinitely variable' cam timing
 

If you have a 'very hot' racing intake cam in your engine,
BUT
with a reed valve/s just behind it
then
You get self adjusting 'infinitely variable' cam timing...

Well not infinitely variable like Koenigseg's FreeValve system, but with a mild exhaust cam; pretty damn good!?

The Honda 500cc single cylinder 'Thumper' had/s such:
https://images.cmsnl.com/img/partsli...e0c02_ff2c.gif

And Alfa Romeo (and other manufacturers) experimented with them, losing ~1kw in top end power for a vast improvement in drivability.
(35% more low end torque apparently)

In those days Reed Valves were made of spring steel.
That meant that if one broke; your engine was a goner.
You also lost some power due to the greater vacuume reqd to open the reed valve.

Nowadays we have carbon and glass fibre reed valves negating the above issues.

If your intake tract bolts to the head, it should be pretty easy to fabricate a bolt on Reed Valve Box.
A bit far from the intake valve, but much easier and simpler than the very beta open source Freevalve setup mentioned in the Freevalve thread.

Some discussion:
https://www.speed-talk.com/forum/vie...hp?f=1&t=42425

Reed valves on a 4-stroke.

I can see this making a big difference in low rpm economy..?
Has anyone here tried this??

'reed valve'
 

As a 'passive' component, in today's sophisticated world of sensors, ECUs, and servos, a non-controlled device like this might be a non-starter, and also redundant.

IIRC carbon fiber is notoriously brittle.

'lamellar'
 

let's see if this works
http://https://ecomodder.com/forum/s...ille-7838.html
Didn't work!
A search for 'lamellar self-blocking grille' located it

Phil, you were soooo close, but too many https://!

https://ecomodder.com/forum/showthre...ille-7838.html

Well if you are running a really hot cam or have the cam timing retarded you get reversion back into the intake manifold, this reversion is what makes hot cams or heavily retarded cam timing make the engine run poorly at lower RPMs. So I would be surprised if adding a reed valve didn't work as advertised.
To be able to take advantage of a hot cam or retarded cam timing the engine has to be spinning faster than about 3,000rpm. Just having hydraulic lifters can tame the reversion on mid range cam grinds that have poor idle quality.

Wrong thread? But I do appreciate the effort.

So the grille self-throttles when the engine is working hard? What could possibly....

I imagine there would be a clacking sound at idle which would be really annoying? Don't see why the concept wouldn't work though, it's basically crude VVT. That said I am not sure this is worth the effort, since it mostly improves idle.

My V8 engine has very hot cams (peak power at 7600rpm) and IIRC it'll idle as low as 620rpm (I have it set to 675, that's about where the fuel consumption stops improving from dropping the speed). That said, if the coolant temp is at say 85C instead of 100C the fuel burn is WAY higher (like 25%), so it's clearly sensitive to that exhaust reversion.

AFAIK some very ancient engines with an IOE valvetrain had a passively-actuated intake valve which was of the conventional poppet layout, pulled open by the vacuum at the intake stroke. But I'm not sure how a reed valve could be so beneficial in a 4-stroke engine which already resorts to mechanically-driven intake valves.

It helps when the cams have too much overlap like on a motorcycle and especially at low load. The exhaust blows back into the intake and screws up the air fuel ratios and dilutes the intake air. The reed valve prevents the backflow and ensures a higher % of oxygen for good combustion.

If you have VVT of some sort; possibly aerohead.
But
I feel that the fact that its passive and relies on the air pressure difference between ambient air the pressure downstream of the valve is in fact the beauty/simplicity of the concept:

Hot and even stock cams open the intake valve before TDC for 2 reasons;
1: To take advantage of the pressure wave in a tuned length intake to start forcing a bit more air in
and
2: to take advantage of a tuned length exhaust pulse sucking exhaust gas out, better scavenging the cylinder.

At low revs (as used by ecomodders) this does not work and you get exhaust going up the intake tract.
That will/can not happen with a reed valve in place.

Similarly; at the end of the intake stroke the valve closes a bit late as the momentum of the inrushing air-fuel gives the engine a slight turboing effect.

At low rpms there is not enough momentum, so some of the air-fuel is pushed out the intake again.
Unless there's a reed valve...

Even the exhaust cam can be somewhat hotter as the reed valve will stop the backward flow at the end/beginning of exhaust/intake stroke.

Basically the intake valve only has to be closed for the power stroke with a reed valve fitted.
The reed valve will provide infinitely variable and almost perfect valve timing at any/all rpms...

IMHO
Any ECU etc would find benefit from and auto adjust to the advantages of the reed valve/s.

And, as said, the restriction of the reeds has been tested and only loses you about 1kw of top end/rpm power.

As I understand it; Carbon Fiber is extremely flexible.
More so than glass
BUT
if you tie a knot in 1 fiber; the fiber will break as soon as the knot is pulled tight.

ie:
Carbon Fiber is extremely flexible up to a certain 'angle'.
That's why other fibers are used in the safety shell of F1 cars etc where said 'sharp bend angles' will occur if the resin is cracked. Fibers that don't break at sharp bends so to speak.

No reason not to do it this way in the old, very low rpm, engines of yore.
But at moderate to high rpms you need way more spring pressure to get the valve to close timeously.
(has way more weight/momentum than a reed)
And that pressure will stop the valve from opening when it should from the pressure difference alone...

The Reed Valve, with a very hot cam, basically gives you 'infinitely variable', valve timing, based on pressure difference...
But a reed valve cannot handle the extreme pressure and heat of the power stroke, so a normal valve is still reqd for that.

I explained more in my replies to aerohead.

A reed valve is a pressure difference driven valve that closes completely aerohead, not an aerodynamic impediment to reverse flow. (what you trying to stop)

https://youtu.be/FohhtYJpQ7Q?t=73

If you want an aerodynamic impediment to reverse flow, look up the Tesla Valve and exhaust anti reversion.

Seems like it wouldn't be much of an issue at all, as hypermilers would avoid to rev the hell out of the engine anyway :thumbup:

Makes me wonder what this approach could do for the Wankel engines...