[rjahl]

Originally Posted by hassmaschine

Its in the XDF under the valve lift settings. Its not either of those..

Found it.

Thanks,

[rjahl]

I logged the updated VVT speed and frankly, it's not showing much. Its a really hard item to catch. It appears that there are a number of factors affecting the VVT motor speed.

1. Difference between Set point (SOL) and actual position.
2. Distance to end stop. I'm seeing a slow down on the last few degrees of rotation.
3. Who is commanding the VVT motor, reaction to Torque reduction commands are slower than the foot pedal. I see these at gear shifts and traction control events.

Regardless, I still see a 500 milliseconds delay after VVT returning to full load before I see the actual Lambda return to the mapped level.

I moved the Max Lift to 12mm and now get about 173 degrees of rotation on the eccentric cam but it seems to fluctuate a little more. I did really short blasts yesterday so that could have been the cause. Fluctuations ran between 172.3-173 degree. VVL set at 9.6 mm yields about 171.5 degrees.

It was hot yesterday and the high AIT's kill the ignition timing. I had AITs above 50 degrees and lost 6+ degrees at certain RPM's. Yes, I had one or two High knock signals (Klopsignals) recorded.

I record a Ping at around 50% load at 2,500 - 3,000 RPM of about 4.5 and I get another around 4,500 RPM under full load, similar value. Normal value would be around 1.5. These seem to be single pings or spikes in the recorded values. I have no baseline from other cars to know if this is too high or not.

[CobraMarty]

12mm valve lift? I thought 9.7mm was the limit.

I vote for grinding the mechanical hard stop a bit and see if you can get more valve lift.

[rjahl]

Originally Posted by CobraMarty

12mm valve lift? I thought 9.7mm was the limit.

I vote for grinding the mechanical hard stop a bit and see if you can get more valve lift.

You're right, 12mm is not possible.

9.7MM is the original limit and that works out to be about 171.5 degrees rotation on the eccentric cam. 9.9 MM, the rated max is at 175.4 degrees on the eccentric cam. That happens to be the physical hard top, I measured that by rotating VVT motor against the stop.

The problem is a soft limiter stopping us from getting closer to the 175.4 degrees. I've tried countless parameters and picking a high Valve lift seems to yield the best results so far. I'm curious how far and can cheat this value.

Grinding the hard stop is not going to much other than through a fault when the VVT checks the adaptations and decides something is wrong.

[CobraMarty]

That makes sense. Great testing. So the max rotation is reached. Need to increase the mechanical side of it. 9.7mm = 0.382" lift is pretty low.

Maybe time for a new/different eccentric shaft, one with more lift. Could weld the last 1/3 and regrind it for more lift. But that's 12 welded lobes and regrinding.

[justpete]

Originally Posted by CobraMarty

That makes sense. Great testing. So the max rotation is reached. Need to increase the mechanical side of it. 9.7mm = 0.382" lift is pretty low.

Maybe time for a new/different eccentric shaft, one with more lift. Could weld the last 1/3 and regrind it for more lift. But that's 12 welded lobes and regrinding. Or the same thing to the eccentric cam followers/links or whatever they are called for more lift.

There's a physical limit with the intermediate rocker against the valve operating rocker arm as you can see in the vid from BPC. There's some question as to how linear this excursion is with lift and whether the operation becomes impossible as lift increases. And there's the concern that peak surface normal forces may cause rapid wear and/or catastrophic failure. This also applies the other way with increasing lift via changes to the cam.

Besides, duration and VANOS timing limits matter more than lift.

[CobraMarty]

OK, just like I thought. I went out to the garage and looked at the N52 head I have sitting on the shelf. I don't have the screw drive, eccentric shaft or intermediate lever.

[CobraMarty]

I wonder if 0.5mm more lift would help these engines?

[justpete]

Originally Posted by CobraMarty

Some more digging. What I called 'black' block is really called a 'Support'.

RealOEM part # 11377583781 $10.13ea and it seems to be the same in all valvetronic models.
ECS Tuning part # is 249042 $13.01

And there are 6 of them.

Valve lift can't go any higher than the cam lobe allows with the eccentric shaft at its absolute maximum rotation, stop or no stop. Pretty much impossible to get beyond 9.9mm lift no matter what. And that's negligibly larger than it is during normal operation now.

Want more lift? No way out, gotta change the cam.

[CobraMarty]

So eccentric cam is maxed out.

[CobraMarty]

Originally Posted by justpete

Valve lift can't go any higher than the cam lobe allows with the eccentric shaft at its absolute maximum rotation, stop or no stop. Pretty much impossible to get beyond 9.9mm lift no matter what. And that's negligibly larger than it is during normal operation now.

Want more lift? No way out, gotta change the cam.

New billet? cam and changing it out sounds expensive.

[justpete]

Originally Posted by CobraMarty

I would rather change the black 'Supports' out instead of a cam change.

Watch the video and pay close attention to the top roller of the intermediate arm at WOT. There is a slight ramp going on there and by angle milling the 'Support' it will effectively increase the ramp. Actually it will 'lower' the ramp position at WOT.
Watch the video again and see what would happen at WOT if the intermediate arm was pushed lower. More valve lift.

Won't work. I've watched the video at least a dozen times and have studied animations and drawings for a couple of years.

Note the heel of the intermediate lever is nearing the end of its travel when the eccentric shaft is commanding maximum lift.

There is no way to get any more lift without taking the heel of that shaft right up to the very end of its extent. Not exactly smart engineering. It'll fail, simple as that. And that's all modifying the stops will do.

The valve excursion is controlled only by the cam once the eccentric has reached its absolute maximum travel, not the intermediate lever arm.

But good luck if you want to try it, please let us know how it goes.

[CobraMarty]

Yeah, unfortunately.

[CobraMarty]

Yeah modifying the eccentric cam stops will not work.
The eccentric cam will rotate a few more degrees and set an engine code and also like you stated, might push the intermediate arm upper roller off the edge.

Sorry guys I kinda got off topic on this thread.

[justpete]

Originally Posted by CobraMarty

Yeah modifying the eccentric cam stops will not work.
The eccentric cam will rotate a few more degrees and set an engine code and also like you stated, might push the intermediate arm upper roller off the edge.

Sorry guys I kinda got off topic on this thread.

No worries, it's nowhere near obvious right up front. The same risk exists for a welded and ground cam that leaves the base circle alone and increases the lobe height. It could push the heel of the intermediate lever off the rocker's roller, too. Bitch of a problem for increased lift. So maybe we need to address duration and coding for various overlap to optimize scavenging, maybe, sorta kinda.

In fact there's some question as to whether the valve lift is a flow limit more important than the rest of the intake tract. Until someone has a head properly flowed we won't really know what a cam could or couldn't do. That's our biggest unknown at the moment, at least as far as I know anyway.

[CobraMarty]

rjahl-
A couple of questions-
So stock VVL is set at 9.6 or 9.7mm and eccentric cam is 171.5*?
What is the VVL at idle and what is the eccentric cam degrees at idle?

[rjahl]

Originally Posted by CobraMarty

rjahl-
A couple of questions-
So stock VVL is set at 9.6 or 9.7mm and eccentric cam is 171.5*?
What is the VVL at idle and what is the eccentric cam degrees at idle?

The attached shows the intake valve lift as compared to RPM and Engine Load. Second map shows the valve lift vs. eccentric cam rotation in degrees.

Idle set points look like they are around 0.2 MM lift. Of course this varies with engine speed and load.

Remember the VVT motor hits stops at 175.4 degrees so that 10.0 MM number is only there to build the curve.

These maps are from a Z4 3.0SI, similar to a 330.

[CobraMarty]

That's just what I was looking for. Thanks.

[hassmaschine]

you would have to log the VVL position at idle to know what the lift "typically" is. There isn't an idle "lift" table, but rather an idle RPM target table - the idle control loop adjusts lift until the engine speed matches the idle target speed, just like on older BMWs it would adjust the opening of the ICV.

[hassmaschine]

Originally Posted by CobraMarty

So eccentric cam is maxed out.

It's not that the eccentric cam is maxed out. The 2nd rocker (which changes the rocker ratio depending on the position of the eccentric shaft) is at the end of it's possible travel on the rocker pad when the eccentric shaft is at it's end stop. Even if you forced the eccentric shaft to move further (don't forget you're also running out of gear on the VVL motor interface), the rocker can't travel any further.

Which brings up something that Pete sent me an email about and I have been thinking too - that I don't think welding the base circle back up before regrinding will work, because then you are still limited by the 2nd rocker at peak lift. Reducing the base circle (just a regrind) might work - the hydraulic adjuster will take care of the reduced base circle, and potentially because the base circle overall is smaller the rocker travel will not be a problem.

Basically it would require some experimentation. Messing with the eccentric shaft is not a good idea. Possibly modifying the rocker ratio could be done, but that sounds expensive. Which leaves regrinding the cam.

I also still think this makes it even more likely that those Shrick cams are really for the N54 and not the N52, aside from the duration and lift not making any sense (and it not being published in their catalog).

[rjahl]

Originally Posted by hassmaschine

you would have to log the VVL position at idle to know what the lift "typically" is. There isn't an idle "lift" table, but rather an idle RPM target table - the idle control loop adjusts lift until the engine speed matches the idle target speed, just like on older BMWs it would adjust the opening of the ICV.

I have a log showing the VVL eccentric cam position at 20-25 degrees at 800 RPM, I guess the air conditioning was on.

[CobraMarty]

That's just what I needed. Idle somewhere between 12-22*.

With a head on the bench, I can measure the eccentric cam's position with a digital angle gauge and get a position of the eccentric cam at idle and then measure valve lift at idle. WOT is a couple of degrees off the hard stop, or even measure the valve lift at the hard stop and measure the valve lift at WOT.

It looks like you can change the intermediate arm ratio so that at idle it is stock lift for any given eccentric angle and at 80%-WOT it will add 0.50mm lift.