Quote:
Originally Posted by Chrisyphus
Lol, it was fun, and I learned something. Win Win.
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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.
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There's a PDF from BMW that explains it all in sufficient detail.
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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
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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?