"In this new Special Series, I document my experiences with the S65 aluminum valve covers from NRW Design. I chat specs, features and first impressions, my installation with a few while-you're-in-there. I'll revisit this later on for long term impressions.
In the first entry: my S65 is obviously pissing oil.
We take a deep dive into what makes the original valve covers doomed and unbox the new aluminum valve covers, documenting why it might be the go-to for eliminating this problem for good. "
The older brother got it right.
The VANOS high pressure system, the oil squirters, the head bolts, the VANOS solenoids, the dual Idle Control Valves, the MAF based engine protocols - there are many areas the S65 improved upon the V10.
There's a key component the V10 got right: it had aluminum valve covers that never, ever leak. My S85 hadn't lost a drop of oil from the valve cover gaskets by the time I lost the engine at 160,000km.
AH! Here's something that has rarely been said about the brotherly dynamics of the S65 V8 and the S85 V10.
It had other types of internal leaking issues that led to its premature death - that's a story for another time.
For the S65, BMW M used cast magnesium valve covers. It's a lighter material than aluminum, with faster casting cycles and easier machine [...] but it had durability issues.
Magnesium's slow downfall.
The magnesium valve covers are exposed to high engine oil temperatures and environmental weathering, this 1-2 combo eventually leads to valve cover failure because of two compounding weaknesses.
It is microporous.
Magnesium has less density than aluminum: it makes it lighter for the same dimensions. Aluminum has better mechanical properties than magnesium: it's more rigid and inherently stable.
As our M3 V8s are now all at-least a decade old, internal gasses have had plenty of time to make their way through the microporous structure and create visual defectves on the valve covers' coating.
The Genuine BMW valve covers ends up flaking by the gasket's channel, opening the way for external elements to start corroding the magnesium: accelerating the cycle and eventually ever slightly warping the magnesium.
The first signs of a warped covers are oil seepage via the valve cover gasket channels. Many have attempted to simply replace the gaskets only to discover the covers were actually warped.
I am currently experiencing this problem on my S65 at around 150,000km. I lose +/- 0.5 litres of oil per 500km of highway driving.
Cast v CNC aluminum
There have been many new valve cover options announced on the market by various brands with the promise to fix our issues for good. I had been intrigued myself to bring a solution to the market and chatted with various manufacturers.
One thing to keep in mind during this comparison is the market viability of these products: the OEM magnesium covers are +/-1,800$ USD.
From my perspective, it wouldn't make sense to have aftermarket offerings higher than OEM.
CNC isn't always the right answer.
CNC has many advantages in terms of commercial viability, it's mostly variable costs. Have your design ready and engineering validated? Start cutting.
However, CNC physically requires more: the machining process removes material from a billet block of aluminum. As a rule of thumb, the more you cut, the more expensive it is.
The current CNC options on the market do not replicate the Genuine BMW design 1:1 in an attempt to hit their target price of 1,500 US by lowering machining costs.
NRW's cast valve covers.
This is where we get into the he said, she said part of the argument. I side with the original designers on this one: BMW M engineers - and where NRW sided as well.
I chatted at length with Neil on what made his aluminum covers the go-to solution versus Genuine BMW and CNC'ed valve covers.
In short: price and design: it's 30 to 40% less expensive than OEM, while replicating the Genuine BMW design 1:1.
The hump is there for a reason.
The NRW design & engineering team consulted with active Aerospace Engineers who examined this feature. They confirmed it was designed is to help control pressures and oil blow by inside the valve cover.
In layman's terms: it’s a vacuum pump design to help with pressures around the oil separators.
Notice the metal plate underneath the lower hole? It's where the oil separators are bolted. This section is walled off for oil to circulate via the hump.
The metal plate is bolted to the valve cover, like OEM. It has a slightly different design, making due without the ribbed sections that BMW added for strength.
The oil cap section.
The oil cap most often leaks on the S65, caused by a failing seal due to the flaking coating of the magnesium covers. Companies tries to tell you the seal of the cap fails to sell you a bright colored billet cap, save your money!
NRW's design matches the OEM, but the lack of coating will make the seal permanent.
The auxiliary fittings.
With a 1:1 design, the auxiliary components such as gaskets, bolts, grommets, sensors, spark plug tubes, oil separators, and ignition coils are supposed to fit like the Genuine BMW part.
The tabs are in the casting itself.
All holes are machined after the casting process to ensure they are perfectly smooth.
The channel for the gasket is precisely machined and smoothened to ensure a perfect seal.
Zooming in on the spark plug tube fittings, we can see the fitment notches were properly machined to fit in the tubes.
The only external change to the Genuine BMW design is the embossed NRW logo. It's purely aesthetic.
The damn grommets.
BMW M have genius accountants, or thoroughly stupid procurement teams - both can be true.
Another example to add to the list is BMW's decision to package the grommets with the valve cover bolts at 10$ a piece - and you need 26x.
This has always been a necessary pain for any V8 owner who has had to replace their valve covers: 260$ for this!?
This problem is solved. NRW provides the complete set of 26x 1:1 grommets for 100$. They are made of silicone rubber and fit perfectly.
Spec your color!
Neil had been refurbishing and powdercoating used Genuine BMW valve covers before he launched NRW. I knew he was going to offer color options along with the infinite possibilities of Prismastic's color catalogue.
I saw everybody getting funky colors with these new S65 aluminum valve covers and I decided to go full normcore: gloss black it was.
Candidly, I expected smooth black to be a smooth satin black finish. It turned out to be gloss - and it's how I described it on the listing.
Gloss does tend to show the casting's imperfections. I wasn't concerned considering where these will eventually sit. No, these aren't white pinholes, it's dust.
Do we nit pick? I mean, we have to! There are extremely small overruns of the powdercoating process.
They do not affect the seal as they aren't in the gasket's guide channel. I might sand it down for pure OCD.
Up next: we source the auxiliary Genuine BMW components to complete the install.
While I'm in there, I decided to get crazy: 292 cams are on the way.