SCH - So how can we determine what causes this?

[jpy1980]

As an owner who bought the F80 to keep for the long haul, the issue of the SCH has caused me to worry a bit. I initially purchased the F80 from the E90 M3 or other generations because I thought certain engine issues were sorted out. Although the RB and TA issues do not seem to plague the F80 platform, it seems like the SCH and to a lesser degree, the leaking intercooler (which my car is at the dealer for - took two weeks for the dealer to fix!) is starting to show up as issues that can arise. Now is there any car engine out there with no issues? Probably not. Am I blowing this out of proportion? No, as it seems like there are other owners who are genuinely concerned as well as trusted shops trying to make solutions for this issue. Do those solutions completely work? Not sure yet, there isn't enough data, although the VTT splinelock and CBC seems to be the most complete solution ATM. Yet, that's not the point of my thread.

I bought my car used at 36k miles and thought I would start tuning the car when it came out of warranty, but instead I just purchased an extended warranty instead and decided to keep it stock. Would I like to tune it and install engine mods, sure. Did the SCH issue make me purchase the extended warranty? Yes. At least now I can drive the car knowing that it will be covered once it goes out of factory warranty, but should the SCH occur, my car will still be down for awhile. What a headache.

Now moving onto the point of my rant: How can we determine what causes the SCH? I really have no knowledge of how these engines function specifically, but I read enough threads that it can happen randomly with old and newer cars, stock or modified, when misshifting, just driving around, on track, etc. It just seems so random.

Is there some type of empirical test that can be performed to figure this out?

I'm genuinely curious on how this issue can be determined. It seems that BMW is moving onto the next generation of engines and not really worrying about this issue, but as an owner of this of generation of engines, I am curious.

I know I may be over my head with this post, but if a reputable company that is very familiar with this engine decides to do some type of official test to really figure out this issue, I'd be willing to throw down alil cash to help the effort.

Regardless, the extended warranty has me feeling better. My wife would kill me if I were out of warranty and had to throw down $30k for a new engine should a catastrophic engine failure occur due to a SCH.

[deluxe 247]

simple answer is no, to do an accurate "experiment" on these cars to determine likely cause(s) is not feasible due to required sample size and money/time involved. You're much better off investing in one of the fixes and praying for the best.

[FriedPiston]

Originally Posted by Railgun

I don't even recall hearing anything like this in the N54 camp, though I guess there are some N55 related SCH issues?

It has happened twice on VTT's built N54 engine, which was rated at around 800+ whp. This was before they came out with their own spline lock solution.

There's also plenty of SCH discussions outside of the F8x world. Here's one for example: https://www.e90post.com/forums/showthread.php?t=1307143

So for anyone looking to surely reproduce the issue, all you need to do is push the N54/N55/S55 into the 700-800whp range without any modifications or reinforcement to the factory crank hub.

OP, best of luck with finding any reputable outlets willing to burn major resources for an engine series that's soon to be out of production, with at least three known aftermarket solutions.

[jpy1980]

Originally Posted by nars3000

It has happened twice on VTT's built N54 engine, which was rated at around 800+ whp. This was before they came out with their own spline lock solution.

There's also plenty of SCH discussions outside of the F8x world. Here's one for example: https://www.e90post.com/forums/showthread.php?t=1307143

So for anyone looking to surely reproduce the issue, all you need to do is push the N54/N55/S55 into the 700-800whp range without any modifications or reinforcement to the factory crank hub.

OP, best of luck with finding any reputable outlets willing to burn major resources for an engine series that's soon to be out of production, with at least three known aftermarket solutions.

Thanks for the reply.

Yea I know it was a long shot, but thought at least a conversation would be started on diagnosing this issue. I’d rather see a conversation instead of threads that claim one shop’s fix works or does not work. Data is important so maybe those shops can share data to help the cause?

Kumbaya~

[G35POPPEDMYCHERRY]

...just pay to fix it when it shits out.....shit happens...not meant tongue and cheek

but like shit happens. youll never get concrete data as this aint no randomized controlled trial...

these crank hub fixes could be marketing schemes since there seems to be hysteria on these fourms for a spun crank hub.

[FriedPiston]

Originally Posted by jpy1980

Thanks for the reply.

Yea I know it was a long shot, but thought at least a conversation would be started on diagnosing this issue. I’d rather see a conversation instead of threads that claim one shop’s fix works or does not work. Data is important so maybe those shops can share data to help the cause?

Kumbaya~

The reality of things is that if anyone were to devote the time and effort for a full root cause analysis, it would have to be BMW themselves. This is one of the main reasons why they have a black box recording thousands of unerasable data through FASTA, so they'll have the basis to analyze the weak points and trending issues with in-house Scientists and Engineers.

On the aftermarket side of things, I spent a few minutes chatting with Tony@VTT at their VHP shop in Hayward yesterday, and what I took from our conversation is that aftermarket companies prefer not to share invaluable data due to the cutthroat nature of the automotive industry. If you make the mistake of sharing too much information, you can bet you'll find your product or idea being copied by a very eager (or shady) business group.

At the end of the day, people just need to stick to basic logic, and learn how to filter personal opinions in various threads about a particular topic. It's more than safe to say there are not many people with a PHd in Mechanical Engineering that are registered on BP, if any.

[jpy1980]

Makes total sense.

[hellrotm]

Originally Posted by Railgun

What's so different about this OHC design than others that this is an issue? Is it a Vanos/Valvetronic issue? I don't see how that's technically possible as I don't see those systems adding much more drag on the crank at all. Or that has nothing to do with it at all.

The 2JZ crank is keyed. While I've never been in that camp, I can't say I've ever heard of any timing issues where the cams get so out of whack it breaks valves and dents pistons. So given the power those can make, which is more than what this platform has so far...

Has the S65 or S85 suffered any timing related issues? Don't think so. So not an RPM thing then....

I don't even recall hearing anything like this in the N54 camp, though I guess there are some N55 related SCH issues?

At the end of the day, something is causing the cam chain to pull on the crank and get out of whack.

There have been some N54’s that have jumped timing. There was a built 135i that was just posted the other day with SCH.

[FriedPiston]

Originally Posted by hellrotm

There was a built 135i that was just posted the other day with SCH.

If you're referring to Ghassan, everyone on the forums were just speculating as usual. They were able to re-time the engine, and keep the same VTT spline lock solution that supposedly "slip"... yet somehow, Ghassan magically came up with their own crank hub solution only a few days after the incident. They've since refused to comment on the issue, or provide any supporting evidence for further analysis.

See: https://goo.gl/uPwYmG

This is why the automotive industry is so cutthroat behind the scenes.

[jpy1980]

Just read that thread. Seems to be something going on between VTT and Ghassan by the way VTT responded to the thread.

Oh the speculation.

At this point I’m happy I paid for my extended warranty. At least my warranty is an exclusionary policy and covers the entire car including the engine.

[overlook637]

A lab could at the very least measure the torque limit for the stock bolt and hub before slipping. VTT did some testing when they designed there splinelock. They just didn't post any numbers.

I too would donate for some testing. I'd like to see static hold torque limit for both clockwise and counterclockwise. Testing using a impact gun to simulate vibrations and shocks during shifting or high rpm vibrations. Also testing using the n54 torque specs; they have the same bolt/hub but the manual specs for a additional 90 degree stretch.

[RedScytheM3]

Originally Posted by overlook637

A lab could at the very least measure the torque limit for the stock bolt and hub before slipping. VTT did some testing when they designed there splinelock. They just didn't post any numbers.

I too would donate for some testing. I'd like to see static hold torque limit for both clockwise and counterclockwise. Testing using a impact gun to simulate vibrations and shocks during shifting or high rpm vibrations. Also testing using the n54 torque specs; they have the same bolt/hub but the manual specs for a additional 90 degree stretch.

The problem is sample size, again as mentioned above. Sure, 1 or 2 or 5 samples can be tested but the data will be meaningless. To generate any data that is of any use you need a large sample size. I'm a biologist and not an engineer, so I'll not even try to estimate the number of samples required to generate any kind of statistically significant engine component failure data. I can only imagine it's going to be more than a few dozen. Maybe an engineer can chime in with a power calculation?

[FSociety]

Originally Posted by nars3000

If you're referring to Ghassan, everyone on the forums were just speculating as usual. They were able to re-time the engine, and keep the same VTT spline lock solution that supposedly "slip"... yet somehow, Ghassan magically came up with their own crank hub solution only a few days after the incident. They've since refused to comment on the issue, or provide any supporting evidence for further analysis.

See: https://goo.gl/uPwYmG

This is why the automotive industry is so cutthroat behind the scenes.

Originally Posted by nars3000

The reality of things is that if anyone were to devote the time and effort for a full root cause analysis, it would have to be BMW themselves. This is one of the main reasons why they have a black box recording thousands of unerasable data through FASTA, so they'll have the basis to analyze the weak points and trending issues with in-house Scientists and Engineers.

On the aftermarket side of things, I spent a few minutes chatting with Tony@VTT at their VHP shop in Hayward yesterday, and what I took from our conversation is that aftermarket companies prefer not to share invaluable data due to the cutthroat nature of the automotive industry. If you make the mistake of sharing too much information, you can bet you'll find your product or idea being copied by a very eager (or shady) business group.

At the end of the day, people just need to stick to basic logic, and learn how to filter personal opinions in various threads about a particular topic. It's more than safe to say there are not many people with a PHd in Mechanical Engineering that are registered on BP, if any.

+100

[M3SQRD]

Originally Posted by Railgun

Has the S65 or S85 suffered any timing related issues? Don't think so. So not an RPM thing then....

The crank hub is an integral (machined) part of the crack shaft on the S85 and S65.

[overlook637]

Originally Posted by Railgun

In any event, is it safe to say it's a BMW issue specifically? .

The Ram truck ecodiesel uses the same type bolt friction set up on the high pressure diesel fuel pump. They have seen a very very small number of failures from that design.