BMW S65 VANOS hub cover options (all inclusive).

[Assimilator1]

Originally Posted by a5m

I know! I thought they'd get annoyed and shut down but nope, went into full detail.

My assumption is Slon, since that's what basically kicked the Vanos Cover discussion off.

Ah, if 'the forum thread' they read was this one, then that thread was not predominantly about the Slon covers, and was started off by talking about another make (which I forget, as it was hard for users to post because the forum filter was blocking the name! It is mentioned in later pages [edit] here).

[a5m]

Originally Posted by Assimilator1

Ah, if 'the forum thread' they read was this one, then that thread was not predominantly about the Slon covers, and was started off by talking about another make (which I forget, as it was hard for users to post because the forum filter was blocking the name! It is mentioned in later pages [edit] here).

Yup that's the thread. Ok so not Slon, could be that one guy who's banned (everybody should know who this is by now lol). It's a long thread so I forget.

[BenFenner]

Yah, I assume they are talking about the old, discontinued aluminum covers designed/manufactured by Euro Power Motorsports and sold through EuroCоnnex*.

Originally Posted by a5m

Once hard-anodised it creates a ceramic-like surface, so the surface hardness of 6082-T6 increases dramatically—interestingly, above that of stainless steel 316 (while retaining the lightweight, thermally efficient characteristics that make aluminium ideal for this environment).


After reading through the forum thread, interestingly the first photo showing the failed raw-aluminium Vanos covers is exactly the same failure mode we experienced with this particular brand.

That's strange they go into the hardness of the anodized coating, then go on to mention "raw" aluminum which is not a thing. For sure the "raw" aluminum in question also had a "cermanic-like" surface coating of aluminum oxide on it because, you know, the atmosphere.


*A string of characters that is STILL censored on this forum. Another of the MANY reasons this thread can't exist wholly on this forum.

[Chrisyphus]

Originally Posted by a5m

Ha, such an engineer. Bought Vanos Units to study. Legend.

Lol, it was fun, and I learned something. Win Win.

Originally Posted by a5m

Many thanks for your valuable insights Chris. I'm just trying to understand the part about the machinist accounting for the movement of the aluminum with time and heat. How would they account for that? Seems that would not be consistent and vary from one machined part to the next?

Essentially, you machine ~95% of the material away, let it age, and maybe heat it up some, then machine the last 5% away, operating under the assumption that this last 5% will be so insignificant that it will not cause significant distortion after the fact. This is called a tolerance.

Loose tolerances are cheap. Tight tolerances become exponentially more expensive the tighter you demand them. If you demand zero tolerance on a part like this, you're going to have 10 steps of machining a little closer to finish dimensions and ageing before the final pass lol. It is the engineer's responsibility to define an acceptable tolerance, and the Machinist's to deliver it.

Originally Posted by a5m

I'll pose this question to Ventrax, who's clip on covers I purchased, and will see what they come back with. In the meantime, I had asked about fitment and choice of material, and this is what the designer of the covers had to say:


Firstly, we selected 6082-T6 aluminium for our Vanos covers because it provides an excellent balance of strength, stability, and machinability for this application. While we appreciate and love the properties of 316 stainless steel, we felt it is unnecessarily heavy for a valvetrain component, increases thermal retention, is more difficult to machine, and adds mass where a reduced inertial load is beneficial. Compared with other aluminium alloys—particularly 7075-T6, which we use for high-stress suspension components due to its extremely high tensile strength—6082-T6 is less brittle, more forgiving in thin, clipped geometries, and less prone to stress-corrosion cracking.



Although 7075-T6 is stronger in theory, its brittleness and lower fatigue tolerance make it less suitable for small, precision-machined parts. In contrast, 6082-T6 combines high tensile and yield strength, excellent fatigue resistance, and outstanding dimensional stability, ensuring the clip interface maintains its shape without deforming. Once hard-anodised it creates a ceramic-like surface, so the surface hardness of 6082-T6 increases dramatically—interestingly, above that of stainless steel 316 (while retaining the lightweight, thermally efficient characteristics that make aluminium ideal for this environment).

Yeah, the surface of the hard anodised 6082 is harder than the surface of 316 (more than 2X, typically), but the added hardness only penetrates so deep. The thickest I have ever heard done was .0004. Typical is closer to .002", (0.05MM)

If you smack 316 with a ball peen hammer and smack any hard anodised aluminium with the same force, the aluminium is still going to look way worse, and now that hard anodised surface has formed microfractures, while the steel has work hardened.

Is it better than raw Aluminum? Probably, as long as it never flexes enough to crack its surface.

As far as their concerns toward weight, inertial load, and thermal retention, that's all fluff. It is abundantly evident that the inertial load of an extra 0.019Kg at a median radius of under 5CM is negligible in every sense of the word.

The fact is that machining 316 sucks. It is way more expensive. There's a reason all the billet goodies are Aluminum and anodized. Aluminium is easier to machine, and anodising hides the ugly tool marks from pushing the machine as fast as possible.

I got curious and did the maths lol. The difference in horsepower required to accelerate the covers on a typical NA S65 is approximately 0.0099 horsepower (TEN THOUSANDTHS). It's approximately 13 watts at peak to accelerate EAE's covers and 5.59 watts to accelerate the Ventrax covers. I say approx because this is an average acceleration over 7ish seconds, about how long it takes to complete a 3rd-gear rip on the dyno. You can safely say the actual value is +/- 50% of the 13 watts required to accelerate, which is 19 watts at the most. For reference, one horsepower is over seven hundred and forty-five watts. No matter what, the horsepower difference stays under one one-hundredth of a horsepower.

Originally Posted by a5m

After reading through the forum thread, interestingly the first photo showing the failed raw-aluminium Vanos covers is exactly the same failure mode we experienced with this particular brand. In fact, that issue is what pushed us to design and produce our own covers.



We still have this failed set we removed from a close friend’s car, and they demonstrate the core problem clearly: the alloy used is far too soft. You can bend these covers with two fingers. With material that weak, the part cannot maintain its geometry under even normal installation force. On top of that, the manufacturer appears to have machined away too much material in critical areas, especially around the clip feature. Because the alloy is so soft, the clip rounds off during installation, and the lack of stiffness allows the entire cover to deform, leading to failure.



Although we don’t have formal lab data from the failed units, we can share our own development evidence:

• Our first set of Ventrax Vanos covers was installed around 3 years ago on a clubsport track car with a highly capable driver.
• We spent 8–12 months testing both on the road and track before releasing the product.
• During this period, the covers were inspected regularly. You can see the cover through the oil-fill hole when trackside, and we also removed the rocker covers multiple times for closer checks.
• None of the covers showed signs of loosening or wear.
• The car receives frequent oil changes as part of normal maintenance, and we never saw a trace of metallic contamination in the oil.
• We can also proudly say, we have never had even one of our Vanos covers fail.

Yeah, that's not as rigorous testing as it would seem... It doesn't look like they've ever actually pulled the covers back off to inspect the edges? They just peeked through the oil fill cap. Still, to their credit, three years without issue, and the testing they did is far more than most shops. They did their due diligence, and I would say it is a trustworthy product.

Originally Posted by a5m

OEM Fitment Problems

We also found that the stock plastic Vanos covers do not fit the Vanos unit particularly well (this is true on the S55 too). Once clipped onto the unit, the OE cover can be rotated clockwise and anticlockwise far more than should be acceptable. The main cause is the sloppy tolerance of the locational key built into the plastic cover—it does not properly fill the Vanos housing slot.

This is just a fundamental misunderstanding of the material properties and purpose of the holes in the cover, as discussed previously. I'll die on this hill lol. The OE VANOS cover could probably spin freely about the hub and not materially shorten the life of the cover. The VANOS cover is made from the same material as the timing chain guides. It's not going to wear from sliding around a little bit because there's play in the locating lug.

As I said previously, the hole is there to identify the correct installation of the spring during engine assembly. The key exists only to keep the window in roughly the right area, and its loose tolerance makes it easy for the low-skilled labourer to pre-assemble it before it is sent to Hans. It has absolutely nothing to do with oil drainage or control. It serves no purpose except for Hans to look through it and think "Ja, das is gut." while tossing the gear on the cam. There are no oil drain ports on the front of the VANOS gear, and suggesting that there are implies a complete lack of understanding of VANOS operation, which is not great for an engineer making aftermarket BMW parts, because I learned all of this this week. Out of curiosity. We're not even making these lol.

There's a PDF from BMW that explains it all in sufficient detail.

Originally Posted by a5m

How We Addressed This

We corrected this by tightening the key/slot fit dramatically. Once our cover is fitted, it has no rotational movement. Because the part cannot move, it cannot wear. Combined with stronger alloy selection, increased local section thickness, and hard anodising, the retention clip in our design maintains its shape even after repeated installation cycles.

These are good decisions; you would need to make these changes if you were using a suboptimal material. Read: Metal instead of an appropriate Polyamide.

Originally Posted by a5m

Whilst we are discussing the design, we also take pride in retaining OEM features wherever possible, even if it adds complexity or cost to the manufacturing process. For the S65 Vanos cover, you will notice we kept the slotted hole on the face of the cover. This aligns with the opening for the clock spring at the end of the Vanos unit. We believe the slot allows oil to flow in and out of this area. While this hasn’t been formally tested, we felt that removing the hole could potentially allow oil pressure to build up, which might directly affect the spring tension and, indirectly, the Vanos unit and cam timing. Additionally, we have maintained the cover’s shape almost identical to the original, except for the slots designed to allow a small amount of flex so the cover can clip on correctly.

See two responses up LOL.

Originally Posted by a5m

We noticed recently that some other manufacturers have removed some of the material around the outer surface of the cover. We believe this is primarily to make the part easier to machine. This area corresponds to the internal stops that define the cover’s depth and position on the Vanos unit, while we don’t believe removing it would cause any functional issues, we just prefer to maintain an OEM+ aesthetic wherever possible.

Mostly fluff, but I am not sure what they mean about removing material around the outer surface. Added machine time is added machine time. Additional material removal is more time. Unless they mean others are using a smaller stock, which means there's less material on the outside? That would slightly reduce material costs and machine time. I'd buy that take for a dollar.

Originally Posted by a5m

I also have an S55 Vanos assembly on hand and can share a video demonstrating just how much rotational play the OE covers have—it’s quite eye-opening and, frankly, a bit shocking given BMW’s usual tolerances.

I find it surprising that someone who is clearly quite intelligent would come to such an incorrect conclusion. "Everything BMW does is exact, except for this injection-moulded part." Machined tolerances are expensive, assembly tolerances are more expensive, designing at such a high level for manufacturability is more-more expensive lol BMW probably spends close to a billion dollars a year on design software licenses for their engineers.

A PERFECT PERFECT PERFECT injection mould of this size would cost ~$50,000 at the high end, and chug out perfect parts at the rate of thousands per day for pennies each. And the conclusion we've come to is that the company that has tighter machine tolerances (within .0002" where necessary) than any other we have ever measured (on average) is sloppy with an injection moulded part?


...okay.

[Chrisyphus]

Originally Posted by BenFenner

Yah, I assume they are talking about the old, discontinued aluminum covers designed/manufactured by Euro Power Motorsports and sold through EuroCоnnex*.


That's strange they go into the hardness of the anodized coating, then go on to mention "raw" aluminum which is not a thing. For sure the "raw" aluminum in question also had a "cermanic-like" surface coating of aluminum oxide on it because, you know, the atmosphere.


*A string of characters that is STILL censored on this forum. Another of the MANY reasons this thread can't exist wholly on this forum.

Hard anodizing does give an INCREDIBLY hard finish for aluminum- approaching the bottom limit of actual ceramics, not just a ceramic-like behavior (shattering and crumbling)

Still, lots of fluff lol, but that's showbiz baby.. gotta make sales to keep making stuff.

[Assimilator1]

Originally Posted by Chrisyphus

Lol, it was fun, and I learned something. Win Win.

.......

Yeah, the surface of the hard anodised 6082 is harder than the surface of 316 (more than 2X, typically), but the added hardness only penetrates so deep. The thickest I have ever heard done was .0004. Typical is closer to .002", (0.05MM)

If you smack 316 with a ball peen hammer and smack any hard anodised aluminium with the same force, the aluminium is still going to look way worse, and now that hard anodised surface has formed microfractures, while the steel has work hardened.

Is it better than raw Aluminum? Probably, as long as it never flexes enough to crack its surface.

As far as their concerns toward weight, inertial load, and thermal retention, that's all fluff. It is abundantly evident that the inertial load of an extra 0.019Kg at a median radius of under 5CM is negligible in every sense of the word.

The fact is that machining 316 sucks. It is way more expensive. There's a reason all the billet goodies are Aluminum and anodized. Aluminium is easier to machine, and anodising hides the ugly tool marks from pushing the machine as fast as possible.

I got curious and did the maths lol. The difference in horsepower required to accelerate the covers on a typical NA S65 is approximately 0.0099 horsepower (TEN THOUSANDTHS). It's approximately 13 watts at peak to accelerate EAE's covers and 5.59 watts to accelerate the Ventrax covers. I say approx because this is an average acceleration over 7ish seconds, about how long it takes to complete a 3rd-gear rip on the dyno. You can safely say the actual value is +/- 50% of the 13 watts required to accelerate, which is 19 watts at the most. For reference, one horsepower is over seven hundred and forty-five watts. No matter what, the horsepower difference stays under one one-hundredth of a horsepower.

Yeah, that's not as rigorous testing as it would seem... It doesn't look like they've ever actually pulled the covers back off to inspect the edges? They just peeked through the oil fill cap. Still, to their credit, three years without issue, and the testing they did is far more than most shops. They did their due diligence, and I would say it is a trustworthy product.

......

There's a PDF from BMW that explains it all in sufficient detail.

.......

Re anodising, is it likely to be broken when the covers are clipped on?
If not, then the covers should last a good while then?
(Hitting it with a hammer is hardly a fair comparison )

19w power loss!! I'm commissioning those Ti VANOS covers now!

Btw, when you said 'they didn't pull the covers back off to inspect', did you mean VANOS covers or valve covers? I assume the former, but they did say they removed the 'rocker[sic] covers' multiple times.

Re BMWs pdf, do you recall it's name?

[Chrisyphus]

Originally Posted by Assimilator1

Re anodising, is it likely to be broken when the covers are clipped on?
If not, then the covers should last a good while then?
(Hitting it with a hammer is hardly a fair comparison )

Maybe? I would not be surprised either way, to be honest, and any speculation beyond that is just a guess.

I did not intend for hitting it with a hammer to be a fair comparison; I was trying to point out that saying the surface is so much harder is only one component of the relevant properties.

Originally Posted by Assimilator1

19w power loss!! I'm commissioning those Ti VANOS covers now!

In this thread, a man plans his future bankruptcy

Originally Posted by Assimilator1

Btw, when you said 'they didn't pull the covers back off to inspect', did you mean VANOS covers or valve covers? I assume the former, but they did say they removed the 'rocker[sic] covers' multiple times.

Yeah, talking about the VANOS covers themselves. I feel like if they took them off, they would have said so, but again, I am speculating.



Re-reading my previous post on the topic, I sound more critical of Ventrax than I am. If I had to choose an aluminum clip-on cover, I would almost certainly select theirs and then never think about it again. They have done good work, and most of their design decisions make perfect sense.

Originally Posted by Assimilator1

Re BMWs pdf, do you recall it's name?

https://ia800902.us.archive.org/26/i...2520Engine.pdf

The whole thing is neat, but the relevant information is on page 13

[Assimilator1]

Thanks for the link , I thought I already had that, as I remember reading it before. Turns out I hadn't, but I do now!