Mike454SS

iTrader: (4)

I'm very curious about this...unfortunately it will only work with Gen 3 blocks as Gen 4 blocks don't have that cam position sensor hole.

What are you putting on the back of the cam to allow it to read cam position? Stock that's where the cam has 1 tooth...which will allow you to read feedback relative to say crank angle...but it's 1 pulse every 2 crank revolutions...which isn't a lot of resolution...I'd like to see something with the resolution of...dare I say it...the LT1's optispark, on the cam.

I also like the idea of using a DC servo with an encoder to drive the delta in the cam "phaser". If our cam sprocket essentially mechanically allows the cam to have so much motion (limited to advance and retard enough that the valves wont hit the pistons should the servo fail), then as was mentioned above...a servo with a real high resolution encoder could be used to control the cam as tight as you want...which would eliminate the mechanical limitations of the current system.

Anyways though...that's all a pipe dream for those of us who are using GM PCM's in vehicles that have that PCM very tightly integrated into them...so for me, at this point in time...if I can add it to my 2010 Camaro...it's going to be using GM's hardware, and GM's control ability...not exactly what I'd want if I could design it myself from scratch...but in my opinion, still better than less technology.

cam

iTrader: (9)

Hey Lance. You always find the worthwhile ones to chime in on eh? Why feedback? Dont you have to go analog to digital with a feedback system?

thats the problem with these goddam e38's they're all half digitized half analog and make no sense. It should be one way, or the other imo. But hey? Im just a frustrated engine swapper whos trying to forget all this nonsense and get back to work LOL

No Hope

Finally an after market guy who is thinking out of the box.

Have you tried a shaft encoder without the DC servo motor for cam positioning? It would give you 360 degrees of positioning and would be easy to install.

Also have you tried putting a transducer on the return oil from the VVT system to help the ECU control the solenoid?

No Hope

Has anyone tried installing a separate electric oil pump dedicated only to the VVT system? You could operate it at a higher pressure than the oil pump for the engine and keep the cam in the correct position if you add lift and spring size.

cam

iTrader: (9)

What would that achieve? nothing more than another oil pump to break. Its not the oil supply thats an issue I can assure you of that. These things PUMP oil haha.

I should clarify what i was yakking about analog vs digital above. I know Lances idea sounds solid in terms of eliminating the current phaser but it only replaces it with half the phaser. Reading the info isnt the issue either its implementing and I dont see anything about his feedback system that implements anything? It just reads so its just more analog info for the ECM to sort out which is already a mess. Kind of similar to haiving a MAF and a MAP almost redundant while Im sure Lance problably has some idea of why we need this, I dont.

All im sayin is skip all that and go straight to a digital rotation of the cam itself. Sort of like a software controlled Variac on the front ( or rear? ) of the cam. Program said RPM = to said cam position in the ECM and voila. Done

No oil, no feedback, no breakin tricky overhead cam set ups and miles of timing chain just cam go here now with one system.

futureuser

iTrader: (1)

Cam,

I think you're on the right track, but you're not thinking outside the box enough. The key is to open and close the valve without the ancient cam and spring. Using pneumatics or some other way to open and close the valve creates an infinite amount of possibilities with unlimited combinations of lift, duration and timing. That is, if it can be implemented before the demise of the internal combustion engine

cam

iTrader: (9)

Desmo? didnt that go the way of the dodo bird? That be desmodronic if ya wanna google it

No Hope

The oil pump that comes with the engine pumps a lot of volume but not enough pressure to keep the cam in place. Otherwise there wouldn't be a problem when a cam with more lift with stiffer springs are installed. An electric pump that pumps less volume at a higher pressure would keep the cam in place.

The best option is not to use the current oil systems but that's not an option yet.

futureuser

iTrader: (1)

I didn't know about desmo, but thanks for pointing it out. Good history. My idea is more like this:

http://autospeed.com/cms/title_Camle...0/article.html

cam

iTrader: (9)

You would have to assume that oil control is the problem. How do you know that? The entire system has not been tested outside of GM development to prove any direct concerns all we know ( all I know anyways ) is that sometimes its faster up top than not. The only new variable from my last engine to this is VVT so.... What proof do you have that the unstable oil pressure you speak of is the cause? In my car it sticks a nice steady 80-90 PSI pending engine temp when at WOT.

Its impressive oil pressure yet no engine noise at all

futureuser

iTrader: (1)

I knew that Ducati had success with eliminating valve springs, but didn't realize that this was the technology you were refering to, and this is in fact the case.

No Hope

Now that's a great idea. You could do it with a bank of electric solenoids. Keep the cam but not for lift instead install prox's (sensors) to read the duration. You would control amount of lift with adjustable stops on the valve.

cam

iTrader: (9)

I suppose whats the real wonder is where does mechanical strength supersede electronic gadgetry? Meaning the law of diminishing returns on power out vs each system with the current tech available with both camps today? Heck its three camps really because even with digital control and monitoring there will always be a point of mechanical translation so long as we want to sit in the car and drive it that is LOOOOOOL

I really hope that made sense to at least somebody

No Hope

What other variable is there? Its oil pressure that moves the cam, yes? So the most likely cause of a cam not staying in its desired position is lack of force to keep it there. 80psi is only equal to 5 bars on a hydraulic scale, not a lot of beef there. And that is at WOT. The oil pressure changes with the RPM of the motor and the ECU has to try and match the solenoid on the cam phaser to the changing oil pressure. With a pump that has no swash plate,that's a lot going on to keep things steady. A separate oil pump with a constant pressure of 150 psi could control the cam more efficiently. Does anyone know how many bars it takes to hold this cam in place fully extended?

I still say a DC servo motor with a shaft encoder is the only option to get VVT where it needs to be. At the least install a shaft encoder to tell the ECU where the cam is at

cam

iTrader: (9)

The actuator assembly and the needle and seat and the fact that its trying to 'horse" around the valve where the oil flows with a dinky 1/4" or so of thrust movement AND that its not mechanically connected Its merely a pin that pushes in on a sprung valve and thats it. If the thing was positively mounted and had an INCH or so of throw it would give the actuator more leverage to "Horse" the position around more accurately and not cause this so called float of cam timing we seem to be facing as it tries to fight high oil pressures and hydraulic power. Command would be the computer talk rather than "Horse" btw.

Still at this point all the theory in the world aint gonna solve jack. Im far from done tuning mine I have a MINT collaborator to work with this Spring and I'll know a LOT more about whats what then. So im kind of done with the guessing again for now

Need hard data

pantera_efi

iTrader: (1)

There could be need of a "stand alone" Quad CAM VVT controller with feedback for modern engines.
There are even some engines that have valve lift change along with VVT.

How could camshaft "feedback" position be achieved with the later LS-x blocks ?

Lance, BTW, I am testing the Econo Plug sparkplug adapters

ClimberD

MegaSquirt MS3 can do it, with some user know-how of course. People have 4-cam BMWs running.

MS3 with expansion board alone should run the L92 without modification. But so will the stock PCM.

No Hope

I think a stand alone system will be the only system for aftermarket VVT cams when the smoke clears on VVT.

I took the limited info I had on GM's VVT to a PLC programmer I work with. He's the best I know when it comes to PID loops and he said what I was thinking, that it was one of the worst PID loops he had ever seen. His guess was that GM was using a sub routine with a formula that no one but GM has access to.

Ed Jankowski

I've replaced AFM lifters at the dealer in trucks with as low as 14k miles, they will get stuck in the bore, not pump up properly, suspect due to deactivation of that cylinder, controlled through the VLOM (valve lifter oil manifold), have a noise, and a slight miss, they can be pulled out with needle lose, and no scoring in the bore. Lifters and VLOM get replaced.

THE PROSSER'S

I am deleting the vvt and dod/AFM in a 2008 vortecmax I have a tuner to shut off just the AFM but not the vvt. my question is can I drive it to the tuner with the vvt physically removed but not tuned out?