[CobraMarty]

So I modified a piece of the Valvetronic valve train and tried it on the N52 test engine I have on the stand.
I am able to measure Eccentric cam angle position and actual valve lift.

So at maximum intake cam lift, I measured and plotted out the stock Eccentric cam position vs valve lift.

Due to the not running engine, the hydraulic lifters were bled down which lost about 1mm of valve lift. I was able to plot from 0* Ecc Cam position to 174* position and got valve lift numbers from 0 to 8.7mm.
Plots below- ADD 1mm to value to get true engine running lifter pumped up valve lift.

Then using the modified part, I remeasured everything and got minimal change, 0.2mm, from Ecc Cam 50* to 140* and above 140* picked up 0.5mm of valve lift.

So it looks like with the modified part, there is minimal valve lift change from 0-140* Ecc Cam position and 0.5mm more intake valve lift between 140-174* Ecc Cam position which corresponds to about 80% to WOT position.

100* Ecc Cam position - stock 5.029mm valve lift - modified 5.156mm valve lift
110* Ecc Cam position - stock 5.663mm valve lift - modified 5.817mm valve lift
120* Ecc Cam position - stock 6.172mm valve lift - modified 6.426mm valve lift
130* Ecc Cam position - stock 6.655mm valve lift - modified 6.910mm valve lift

140* Ecc Cam position - stock 7.122mm valve lift - modified 7.366mm valve lift
150* Ecc Cam position - stock 7.569mm valve lift - modified 8.103mm valve lift
160* Ecc Cam position - stock 8.103mm valve lift - modified 8.611mm valve lift
170* Ecc Cam position - stock 8.560mm valve lift - modified 9.093mm valve lift
174* Ecc Cam position - stock 8.712mm valve lift - modified 9.347mm valve lift

Now to machine more pieces and install on a running engine and test.

[boro92]

Subbed for results!

[hassmaschine]

Cool! Clever that it mostly seems to change the top end of the curve, which is what we want. Well, since you went through the trouble of plotting it out - you should be able to alter this curve so the DME is happy:





The actual safe maximum is about ~178 degrees - so it looks like with your modified rocker ratio, 10.5mm of lift should be possible even with a stock cam.

Notice most of the resolution in the curve is at the low end - I think that's the critical part to get correct, as that will affect most of the low load/drivability areas. Once you get to the end of the curve, the valves are mostly open and it probably matters less.

Is this something you intend to sell?

[rjahl]

Very Cool,

Pictures of the mod? When to you plan on running it?

[CobraMarty]

I hit the stop at 174*, maybe 176* max if I force it, but does not go to 180*. Now that is with my digital angle meter attached to the end of the Ecc Cam. When I set it and calibrate it, the meter seems to be right and accurate.

I get no reliable valve lift values under 50* which I believe is due to lifter collapse.

I'm not too good on my graphing skills, but computing and extrapolating some values-
75* - stock 3.860 - mod 3.947
90* - stock 5.010 - mod 5.369
120*-stock 6.920 - mod 7.426
180*-stock 10.10 - mod 10.728

But I think in actual engine testing, the stock max valve lift is 9.7mm and with my mod, it should be 10.335mm.
A gain of 0.635mm which is 0.025" more/additional lift at WOT.

That is the whole point of this, use the stock cam and get more lift at 80-100% throttle position (140-175* Ecc Cam postition).

The cost of a new billet or re-ground Eccentric Cam or Intake Cam is very expensive and the install is much more involved, I thought that modifying the 'linkage' to increase the ratio would be an easier modification and install and cheaper than a new intake cam.

I have a couple of more mods to try and test on the test engine and then get more pieces machined and try on a running engine.

Nearly the hardest part of this whole thing was the pulling of the damn Valve Cover. What a bitch of a job. Book says 2 hours to replace the valve cover gasket which would need to be done and the modded parts would require about 30 additional minutes to install.

Sell? IDK, liability and cost issues. I would have to test it on my own vehicle and be 100% sure it is 100% reliable before I would even consider such a thought.
It is more of a 'it can't be done' / 'personal project' than anything else at this time.

[Taskmaster]

Well, this is interesting - but you never got back to me...

[hassmaschine]

I think a better way to measure the eccentric cam position would be to hook up a DME to it and log the values from the EC sensor, so you're looking at exactly what the DME is seeing - then just rotate it to the values in the original curve and measure the lift.

I think if you are right that the low lift values are not really altered, then you probably can leave that part of the curve alone. Maybe you could also use a 1mm shim to make up the difference?

the EC shaft can definitely rotate past 175 degrees though.

[CobraMarty]

And I don't even know if the extra valve lift will make much difference in power. The N52 does not seem to be head or cam limited. But maybe it can bolt on and work without any computer tuning and adds 5-7hp. Just something else to add on like a PE, PI, charcoal delete, front air scoops, headers, 3 stage intake, silicone intake duct tubing and ECU tune, which all add that 2-3hp/3-5hp/5-7hp range.

This is like 1 of 100 projects on my plate at the present and along with the holidays, birthdays, work, end of the year, It will be a slow process.
But I have invested in a cylinder head, complete engine, a bunch of 335 N55 turbo parts, header flanges, additional port injection manifold, 3 stage intake, etc.
I have 4 sets of parts I need to make this mod.
Next is I need a new commuter car for work and maybe get another '07 328xi and use it as a test vehicle. I don't want to put anyone at risk, I would rather break my own stuff.

Also the same modded parts are used on all the valvetronic engines so there is crossover with the N55 and other engines. I am sure the extra lift will help the boosted engines make more power.

More to come...

[hassmaschine]

I don't see why it wouldn't make more power. At least, you would need to rev higher - so this would be pointless if you have an AT. But if you want to hit an 8k rev limit.. well..

If you are willing, I also have an engine on a stand that I'm working on (at a glacial pace). I would like to test this on my head as well.

[Taskmaster]

Originally Posted by hassmaschine

I don't see why it wouldn't make more power. At least, you would need to rev higher - so this would be pointless if you have an AT. But if you want to hit an 8k rev limit.. well..

If you are willing, I also have an engine on a stand that I'm working on (at a glacial pace). I would like to test this on my head as well.

^

[justpete]

Pretty cool! A little less than the cost of a regrind although labor would be less, I think. Very interested in seeing more test results.

[rjahl]

Originally Posted by hassmaschine

I don't see why it wouldn't make more power. At least, you would need to rev higher - so this would be pointless if you have an AT. But if you want to hit an 8k rev limit.. well..

If you are willing, I also have an engine on a stand that I'm working on (at a glacial pace). I would like to test this on my head as well.

You sure the extra lift won't do much at lower RPMs?

[CobraMarty]

'glacial pace' - that's funny and really true.

I'm not even sure if a re-ground cam would even work in the valvetronic mechanism. The problem is the re-ground cam leaves the peak of the lobe where it is and makes the base circle smaller. The geometry of the valvetronics doesn't look like it would compensate and make more lift. Watch BPC video on the N52 head especially around 3:45 onward. Even a different cam with a higher peak would push the intermediate and rocker off their ends. It's a very delicate/precise dance the whole valvetronics mechanism performs.

The stepper motor- 1 revolution is about 7* and from min stop to max stop is 25 revolutions, 25.25 if I force it. That is 175* to 176.75* which is right where I measure. I could grind the max stop to get to 180*.

[CobraMarty]

Originally Posted by justpete

Pretty cool! A little less than the cost of a regrind although labor would be less, I think. Very interested in seeing more test results.

What is the cost of a re-ground cam?

[CobraMarty]

On other engines where I have added increased ratio roller rockers, the power was up across the whole powerband not just top end.

[justpete]

Originally Posted by CobraMarty

What is the cost of a re-ground cam?

$450 or $550, my archived emails aren't real clear.

[CobraMarty]

It could be done for $350 but that is way, way down the line if ever at all. My interest is the problem and finding a reasonable solution.

I guess the real question is what is the real problem? Is it just how to get more valve lift? Is it the N52 head the limiting problem? Is it the cam and valve lift the problem? Will more valve lift produce more power? Will it be usable power?

[hassmaschine]

Originally Posted by rjahl

You sure the extra lift won't do much at lower RPMs?

no, I'm meaning the lift doesn't change much at smaller eccentric shaft angles - not that you won't see a benefit at lower RPM. That's a good thing as the low-lift areas are important for idle and driveability, where full load is easier to deal with changes like this.

[CobraMarty]

That exactly. This variable valve lift is basically your throttle position via the eccentric cam and not rpm controlled.

Up to about 80% throttle position/eccentric cam position everything works and drives as stock or very near stock. Beyond 80% throttle/Ecc Cam position there is more valve lift.
I guess it is sort of like a bigger throttle body (but we don't have a TB) and the 'valve lift' is the 'TB'.

[justpete]

It sounds like an elegant solution but I'd rather have duration and lift even at the expense of idle stability and rpm.

[hassmaschine]

Well, how about a modified rocker ratio and mechanically retarded intake cams... It would be inexpensive and have most of the benefits of custom cams.

[justpete]

Originally Posted by hassmaschine

Well, how about a modified rocker ratio and mechanically retarded intake cams... It would be inexpensive and have most of the benefits of custom cams.

Would be a lot cheaper. How much performance would you be giving up over regrinds, theoretically, I wonder...