Variable Valve Timing

[Alvor315]

I'm not quite done yet, but I've been working on this design for a while, and I wanted to see what you guys thought.

This project is also the reason I wanted to know how the valves rotated in the head. I'm hoping that by switching to a roller-rocker setup up that valve rotation will not cease entirely.



This is of what it will look like when it's mounted on the rocker arm bar.
In the following pictures I have removed one side of the actuator.



The pink object is the actuator. By rotating the actuator the amount of lift varies.



When the push rod pushes on the ball, the green arm will transfer the force, rotated about the blue shaft, to the yellow cylinder and thus transfer the force to the green cylinder connected to the second red piece of the rocker arm.



While the pink actuator is nearly horizontal, like it is now, the yellow cylinder will deflect the red part of the rocker arm very little.



When the actuator has been rotated, like so, all the force from the cam shaft will be transfered into opening the valve.

I'm using the general Pattakon design for this setup, but I have modeled everything to scale for our sixes with a 1.6:1 rocker ratio. Here is their generic design for the rockers.

http://www.pattakon.com/vva/SideCam.htm

All I have left to figure out is the oiling, which I plan to still have running through the center shaft, to allow the entire thing to be bolted directly to the head and allow the user to use what ever type lifters he/she wishes.

Any critiques/questions/comments would be much appreciated.

Allan

 

[69Falcon]

Holy crap! (And I'm not being facetious!) That is very cool.

I took a brief look at the website, and if I understand it correctly, you adjust the actuator with a split throttle cable; one goes to the carb/tb the other to the actuator. They claimed to be able to get the idle down to 300 - 350 rpm; for those of us with automatic tranny's that might prove problematic as the torque convertor might not engage that low. When you get to real world testing, I would start with a manual tranny to eliminate that variable.

Just my opinion, but with the radically different lifts over the rpm range, it might make tuning a carb, or even FI maps, a lot more difficult.

And you'll have to consider the actual cam profile, figure out what will work best for this setup.

But all in all, pretty cool! I look forward to progress reports!

 

[Geezer 300]

Fascinating!!

 

[Alvor315]

Actually you can eliminate the throttle body all together. Because you can control the amount of air entering the cylinders by valve lift, you can take the butterfly valve off your carburetor and let it run free floating. That may prove difficult when you need a choke for warm up, but if you were to use fuel injection, I don't really see any problems. BMW actually runs on this principle with their newer engines.

Allan

 

[Patrick66]

looks interesting. when do you think youll have a prototype ready?

 

[Alvor315]

To be honest, I'm not quite sure. I have neither a mill nor a lathe, which I would assume would be the two vital tools for making such an apparatus, so I'll have to take a class at the local community college. Perhaps several months, as an optimistic estimate.

Allan

 

[rhetor]

Looks like you'll need a cnc vertical mill to get those shapes.

If you are able to switch to pure radius corners, you could do those on a bridgeport!

If you are simply looking for variable lift on a pushrod motor, it is probably easier to do so on the other side of the rocker. For an overhead cam setup, where space requirements inhibit any modification of the cam followers, this looks like a good idea!

Too many parts IMO for a production vehicle, but could have good value as a prototype or concept.