I have been designing a kit that will turn a Chevy small block into a camless engine. I am waiting for the patent to be approved and I am looking for a manufacturer right now. I have been advised not to disclose design details until the patent is approved so I do not have a website yet. I am assuming that you guys know the benifits of having infinitely variable (and programmable) valve lift and timing across the entire RPM range. I wanted to ask you guys for some input, if that is alright.

1. If I prove that this system works by installing it into my own car, how many of you would be interested in this as a performance upgrade?
2. How much would you be willing to pay?
3. What features/performance gains would you expect to justify spending that amount of money?
4. Should thirdgen.org users get a discount for answering these questions?

My goal is to make this technology available to the average do-it-yourselfer (like myself and many of us here) and make it affordable as well.

I know this seems like a questionable idea to some of you, but I am serious about making this a reality. Your answers (and possible questions) would help me out tremendously.

 

post a pic.

 

I can't post a pic of the finished design, but here is a very early and incomplete REPRESENTATION of the system. Pretty much the piston assembly replaces the rocker arms, manifolds are bolted doen where there is room for them, holes must be drilled into the valve covers to allow hoses to connect. Many things such as seals, scale and dimensions, sensors, wiring, pump, cooler, hose type & diameters, pressure regulator, solenoids, etc. are not included in this. I have been advised, for business reasons, not to disclose these details until the patent is approved. I also know how annoying it is when people tell me how something works without showing me something to clarify. I hope that this gives you an idea of how easy this system will install (well except for oil delivery mods that will also be necessary).

 

Hydrolically operated valves work well for a large container ship 2-stroke, where the max RPM is about 100. But for a gas engine, the response must be much faster. Have you considered if the unit can actuate valves at up to 3500 times a minute? How do you plan to move the fluid that quickly? How will you control the unit? How do you plan to modulate the fluid to get the proper valve actuation profile? How will you pump the fluid? What was the basis for the design?

Not trying to be a ****, just asking some sanity questions. It looks like the unit will not be able to respond anywhere near fast enough to actuate a valve, or be able to produce an accurate lift profile. On top of this, it would take a pretty fancy hydrolic pumping and activation system as well as sophisticated control electronics to make it work.

 

This is something the OE's have been working on for years, it would eliminate the throttle bodies EGR valves and a host of other mechanical devices.

The benifits would be electric motor like power and torque production, a motor that can operate well at idle and low RPM high load while still breathing well at the top end.

Actuator speed and stregnth are the two major restrictions holding such systems back so I dont have a whole lot of faith that it'll be cracked by a small one man operation but I wouldnt doubt that it can happen.


A more realistic intermediate option would be an adaption of variable cam timing to the sbc (already done atleast once but not produced) or a more functional evolution of the rhodes lifter.

Or you might adapt the kinds of advanced cam lift and timing devices being used in new cars like Hondas AVTEC and BMW's new variable lift/duration setup.

Basicly they use variable ratio rocker assemblies to control lift and duration.

Such a setup could in theory be adapted to the SBC head and given enough range could even replace the throttle body/carb.

 

What about igntion timing? Would you include a computer controlled distributor with the system and the computer also, or is the not part of your plans?

 

1

 

that 1 was a mistake

 

It seems to me that part of the problem would be that a valve spring is still needed. In order for the valves to seal, you need lots of seat pressure from the spring. So, the valve actuator, whether hydraulic or electric, needs to be able to overcome that spring pressure, and very quickly.

Also, someone correct me if I'm wrong, but the shape of the cam lobe comes into play as well. With a camshaft, the valve doesn't just bang open and bang shut, instead its in almost constant motion. It has an opening curve, and a closing curve. The computer controlled setup would likely need some way to mimic this, I'm not sure what effect it would have to just have the valves slam open and shut.

It might be easier to design a computer controlled rotary valve setup (not rotary engine, but rotary valve), since that at least eliminates the valve spring, and would be easier to control the open and close curves.

 

like a desmodromic overhead cam?
AWESOME!!

sounds like a gread idea OP, but i have a few questions
will it be fast enough
will it be reliable
will it be any real gain

i dont remember specifics, but a few manufacturers have tried this before
one system used solenoids to actuate the valves.
another used an air compressor and air pressure to open and close the valves.

both systems worked beautifully
HOWEVER
they were far too complex and heavy to be practical
also the air system couldn't sustain enough pressure to run at high rpms for extended periods.

the thing you have to realize is that you are replacing a mechanical device that runs off the engines power with a device that has to provide its own power.
i cant say how much power a SBC valvetrain takes to run, but your average engine has 300 hp so its got a big power supply on tap.

i dont know if this is going to be a electrically driven system, but say a typical valvetrain requires 2 hp to run:
thats 1500 watts of power, which at 12v, will draw 125 amps.
we can say just for the heck of it that your system will require less because there is no friction between the cam and the lifters, just the actual force to open the valves.
so call it 100 amps at 12v.

im not saying that its not doable, and you have probably accounted for this, but thats a lot of power.
it would require a re-wound or higher capacity alternator for sure
not quite plug-n-play

i personally, would devise a way to run the pump off the engine to get rid of conversion losses (mechanical ==> electrical ==> mechanical)

another thing is what happens to the cam?
run a cam but no lifters pushrods ect?
the oiling system would have to be completely changed as well...

its going to be a lot of work, but if you perservere, it CAN BE DONE!

 

These are all very good questions and concerns. I am preparing a very detailed explanation of the system and hopefully it will answer most, if not all, of your questions.

 

ok, i did some thinking (never a good thing by the way)
you use pressure from a pump to push the valves down
what happens to the oil on the return stroke of the valve?
also, i second the notion that you will need valve springs to control the valves.
either you will need a desmodromic valve or you will need valve springs.

earlier i mentioned that you would need to figure out the power required to run the valvetrain in a typical engine.
i used a value of 2 hp that i pulled out of my a$$
the thing that i did not realize is that with a cam, you compress the valve springs to open the valve, but when the valve closes, you essentially "get back" that energy...
in this sense, you really only need to overcome friction between the cam and lifters, and the rockers as well as the lifter bores and the lifters ect...

if your design uses pressure to open the valves, then the oil returns to a tank to be pumped up to pressure again, then you have essentially "wasted" the spring energy delivered by the return stroke of the valve spring.

i did some math (again, a bad idea) and the numbers are not looking good.
hopefully someone can poke some holes in my math, but i have been over it a few times and it checks out 100%

first, determine the spring rate of the valvespring using seat pressure and open pressure:
using common values of 125 lb seat and 300 lb open, and a valve lift of 0.5" i get a rate of 350 lb/in using the formula F = k * X

this checks out against research i did.
using 322 lb/in i next found the potential energy stored in the spring at max lift using U = 0.5 * k * X^2
this gives a value of 43.75 in-lbf of stored energy per spring
multiply this by 16 springs and converting to ft-lbf (more common unit) gives a value of 58.3 ft-lbf stored energy if ALL the springs are fully compressed

now: power is simply a measure of energy delivered per unit time, so i found the power next.

using 58.3 ft-lbf and assuming 500 rpm (idle) i found that it would require 26.5 hp to open and close all the valves.

and again, at 5000 rpm, it would require 265 hp...


i think that this is right because you will be releasing the oil pressure to release the valve so you dont get to recapture the stored energy in the spring...
hopefully there is something wrong with my math, but it seems to check out pretty solid.
if anyone wants to take a stab at it, feel free!

 

The oil could presumably be used in a regeneration loop or even be vented to another actuator (with a little extra help from the pump to make up for losses) to open another valve.

Also the actuator could be positively attached to the valve to allow it to close tha valve when fluid is introduced to the back side of the actuator piston.

Ward... The shape of a cam lobe is forced by the physics involved in a conventional valve train. Speaking in very general terms all performance cam grinds are attempts to open tha valve a quickly as possible. If a camshaft could describe a square sine wave type motion rather than the relatively gentle curves they are restricted to then builders would be all over them.

In other words idealy the valve could be opened to it's max lift position instantainiously and closed as fast, this would allow similar performance with less total lift and duration. but for obvious and not so obvious reasons thats not possible in a conventional actuation system.

I can almost imagine a billit assembly placed on the head with 8 double actuators secured to the valves with each actuator being fed with high pressure engine oil controlled by multi position solenoids.

The inside of the main block would look like a transmission valve body with large passages transfering fluid from one actuato to the next at the command of the solenoids.

The reality of that kind of fluid management is tough to get around though.

 

At 6000 RPM, the engine makes one revolution in .01 seconds or 10 milliseconds. The way this system is set up at the moment, .57 cubic inches of hydraulic fluid must be displaced for .500 lift per actuator. 8 actuators will move 8 different valves per revolution in the Otto cycle. I know that more than 8 valves can be moving during one revolution but keep in mind that I am making this explanation as simple as possible.

So at an imaginary redline of 6000 RPM, this system must flow 4.56 cubic inches of fluid every 10 milliseconds. The solenoid controlling the flow of fluid must switch, wait for .57 cubic inches of fluid to flow, and then switch again within 10 ms.

The amount of time it takes for the fluid to flow is dependent on pressure, viscosity, and passage diameters. In theory, pressure should be in excess of 3000 psi to allow this system to overcome combustion chamber pressure during extreme operation.

The amount of time it takes for a solenoid to switch is around 28 milliseconds. That is the fastest hydraulic cartridge valve I have found so far. The hydraulic company I am consulting with says that this time is dependant on voltage as well as fluid conditions. I am still trying to find out what standards are used when the manufacturer determines the switching speed of their solenoid. I am hoping that increasing the voltage will allow these to switch in 10 milliseconds or less. Or I may have to have them custom made.

I am positive that if a fuel injector can accurately maintain 80% duty cycle at 6000 RPM, then there is a way for this system to work. Fuel injectors are solenoids as well and they manage to switch fast enough.

As for harnessing the energy from the the valve springs, I havent thought of that. There should be some way to make this system more efficent using that energy and I will try to find that out.

In reality a completely new block should be designed, and custom heads that are machined with fluid passages for a system like this. That is not a logical or cost effective way for me to start this project.

This is not the detailed explanation I promised but kinda covering the only limitation of this system... solenoids.

 

RED_DRAGON_85:

The cam must stay in order for this kit to install as simply as possible. I am pretty sure that even thought most people would like to upgrade to coils they dont want to be forced to. Cam has to stay in to run the distributor.

Correct me if I am wrong... the only oil problem, considering the cam stays in, is to get oil to the springs. This should be no problem at all to accomplish. I believe that I handled it well enough in the finished (well not finished because I am working on it everyday) design used to apply for the patent.

As for the pump, the only logical thing to do is use a mechanical one. An electric pump would be a lot more convienant but the power consumtion would be way too much. I plan on using an electric pump for the first physical prototype only because the hydraulic company I am working with offered to let me use it for free. These guys are awesome. I thought they would laugh me out their store 1 year ago but they actually helped me improve the design.

If you are ever near Mooresville, North Carolina and need some help with hydraulics, look up Lake Norman Fluid Power.

 

deleted:

 

Fuel injectors flow a fairly small volume of fluid compared to what you'll need and they dont (except in the case of direct injection) actualy sync up with the cam cycle.

Even with sequential injection the injectors fire a good amount of the time to a closed valve, that's because they usualy dont flow enough volume to feed the motor in the span of time the valve is actualy open.

 

The flow is dependant on pressure, viscosity, and orifice size. I have the flow necessary to support 6000 RPM. What I meant by the comparison to fuel injectors was that there are solenoids capable of switching fast enough to be accurate up to 6000 RPM. The only downside is that they are expensive and will nearly double the cost to have this manufactured.

 

yes and no.
typically, at max power, the injectors are at 85% or more duty cycle which means that they are spraying 85% of the time... not just when the valve is open

 

Each valve must open once per Otto cycle, or 1 out of every 4 strokes. The same that a fuel injector opens once every 4 strokes. This means that the solenoid must switch 2 times (on and off) every 4 strokes or 2 times every 2 rotations. What I was saying is that if a solenoid, such as a fuel injector, is capable of switching twice every two rotations, then there is a solenloid that is capabl of switching fast enough to support actuation of the valves at 6000 RPM. The problem is that the higher pressures that a hydraulic solenoid must overcome mean that the solenoids must be made of high quality heavy duty parts and will require more electrical power to opperate at that speed.