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11-20-2013, 08:27 AM | #1079 |
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That would be a great shame...the topic needs as many clear, informed and articulate heads as possible. Especially one who can put his hands up to a comment written in frustration. I think the S85 issues have great relevance as they give context to those that the S65 may or may not have.
Last edited by SenorFunkyPants; 11-20-2013 at 08:38 AM.. |
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11-20-2013, 10:55 AM | #1080 | |
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Also in the article, it says this: "With regards to the hydrodynamic conditions the bearing with an eccentricity is equivalent to the bearing with an increased diameter (or increased oil clearance). The oil wedge of the bearing with eccentricity is the same as the wedge formed by the bearing with an increased diameter (”effective bearing diameter”). On the other hand the actual bearing diameter is not changed..." So my question is: could this reasoning explain BMW's use of tight con rod bearing clearances? The fact that they go higher on bearing eccentricity? Is that the point of this eccentricity test? Sorry if these are dumb or repeated questions. I'm really trying to keep up! Pat |
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11-20-2013, 11:05 AM | #1081 | |
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11-20-2013, 07:37 PM | #1082 | |
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1. These number are preliminary based on used parts. Thus the new part numbers are more likely to be closer to the standard. 2. 3/8 ths of the shells are within the spec. 3. The spec is just like the Clevite spec, a basic guideline not a firm unbreakable rule. 4. The spec is pretty wide - a factor of 2, as are the measured values. I like the thinking and again would not be a bit surprised if it is a contributing factor to BMWs alleged way to tight spec, but I certainly don't think this solves the mystery.
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11-20-2013, 07:47 PM | #1083 | |||
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Your desire is understood and certainly partially shared yet at the same time it's also naive. Quote:
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I didn't really find your post too hostile myself, I didn't really agree with it but I don't think it was "hostile". You've definitely contributed to this ongoing discussion and I'd encourage you to keep on doing so!
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11-20-2013, 08:13 PM | #1084 | |
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Interesting. At WOT after 7,500 rpm, stock timing target is 32 degrees. At what point does advancing timing become too dangerous? Think most tuners don't target more than a couple of degrees higher than stock.
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11-21-2013, 03:05 AM | #1085 | |
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You do have to wonder about the benefit of trying to add extra degrees of advance to a engine that is already having to pull back the timing to hold it at the edge of detonation on 91 Aki at high load...Surely the only performance benefit would be if this then translated into less retardation of the timing as the ionic current sensing system was trying to control detonation....and that would not seem to be a good idea at all in the long term. Also back a hundred posts or so when Yellow Snow queried why we aren't seeing any recorded engine failures in the UK...fuel was the only thing that occurred to me. But there is something else, UK owners as a rule don't tend to modify their engines in new or newish expensive cars like the M3. The demographic for the typical new UK M3 owner is for a much older professional compared to that say of California. So here is an thought...could it be that the reason that Ca sees more than its fair share of failures is due to the fact that an M3 is far more likely to be (engine) modded in California than anywhere else in the world? Which when combined with 91 Aki only further increases the potential for damage. It would also help account for why most undamaged engines that are opened find increased bearing wear....as who else is most likely to open up an engine (in preparation to say fit a supercharger) than someone who is into engine modifications and may well have run some sort of tune. Bit of a stretch but it might be a factor. Last edited by SenorFunkyPants; 11-21-2013 at 09:00 AM.. |
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11-21-2013, 04:08 AM | #1086 | |
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M5 S85 Bearing failure - engine tune Bearing failure at 143000 miles UK Unknown cause of failure Oil analysis only Knock wasn't bearing. Bearing failure maybe caused by Vanos oil pump failure. Engine tune Bearing failure - engine tune Bearing failure - engine tune Bearing failure - engine tune Bearing failure Bearing failure Bearing failure 12 cases. 10 USA, 1 SA 1 UK. 2 not a failure 1 unknown cause 1 suspected due to Vanos 8 failures where the cause was almost certainly bearing failure. 5 cars had some form of ECU tune. 3 cars that don't state a tune. Thats not a lot of failures in stock cars. Last edited by SenorFunkyPants; 11-23-2013 at 09:07 AM.. |
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11-21-2013, 06:16 AM | #1087 |
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Had another look at the S65 engine failure registry.
19 links on page 1. 1 failure due oil pump 1 rod snapped. 1 Cylinder/piston damage. 2 crankshaft failures 2 No failure. 2 Valve failures 3 failures of Supercharged engines 7 almost certain rod bearing failure So there you go...its not as bad as you thought. Last edited by SenorFunkyPants; 11-22-2013 at 05:32 AM.. Reason: changed bearing to engine first line |
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11-21-2013, 06:51 AM | #1088 | |
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11-21-2013, 07:40 AM | #1089 | |
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11-21-2013, 10:27 AM | #1090 | |
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Factory tunes are set to optimize performance and safety over a broad set of parameters and conditions. A lot of analysis goes into setting up the factory parameters. Most tuners almost certainly don't have that level of investment nor do they have to stand behind their work, economically speaking. Pat |
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11-21-2013, 11:33 AM | #1091 | |
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11-21-2013, 12:09 PM | #1092 |
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I suppose that if there is not much wiggle room with the ignition timing then that leaves fueling....what can you do with that, run a bit richer?
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11-21-2013, 12:11 PM | #1093 | |
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11-21-2013, 04:56 PM | #1094 |
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I would like to hear from Mike Benvo of BPM Sport as to what his thoughts are on this bearing issue especially with ECU modification. His tunes are very conservative compared to others. His input here will be invaluable. But for some unknown reason he is banned from this forum. Forums are all about knowledge sharing and helping each other out but some one on this forum has an axe to grind against Mike, and keep extending his ban even when he is not posting. Isn't that funny.
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11-21-2013, 04:57 PM | #1095 | |
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11-21-2013, 06:27 PM | #1096 | |
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Agreed, would be interesting to hear from the major tuners. I have logged (on rolling road) timing with BPM tune and can attest to the conservative timing numbers ie 32-33 degrees at WOT. Would like to know at what point too much is too much before it gets dangerous for the engine.
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11-22-2013, 12:22 AM | #1097 | |
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Also great summaries in your posts following this one analyzing and summarizing the cases surrounding the reported S85 and S65 data sets. IIRC regular_guy claimed that no failures here were SC and many/most had no outward signs of problems. There appears to be a fairly large contradiction here??? This same line of reasoning led to my post here long ago in this thread asking why the heck are all of these bottom ends with "NO apparent problems" are being torn down for "inspection". I also made the incorrect claim that if you tear down an engine with outward signs of problem and then find problems, that should not be much of a surprise. regular_guy corrected this mistake of mine which I acknowledged. I think someone else here hinted/stated that one or more companies installing SCs REQUIRE bearing inspection/replacement. regular_guy and SFP please resolve this somewhat glaring contradiction. According to SFP's review HALF or less than half of the cars are truly "no issues" engines inspected and found to have some significant bearing wear. Depends on if you do or don't want to count the damaged cranks and/or siezed/"grenade" cases. For the S65: ~10 cars for the entire US/Canada production (no separate US figures) is 0.04% ~10 cars for the entire world production is a whopping 0.017%
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11-22-2013, 01:12 AM | #1098 |
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SFP is incorrectly lumping together failures that I never included in this discussion and should not be part of this discussion. I've tried to limit the scope of this discussion by excluding blown motors without photographic evidence or forensic failure analysis. The only exception also happens to be a primary focus of this article: bone stock motors with less than 25000 miles (not supercharged motors, and not broken valve springs). You will not notice any comments of mine in the 20+ threads being referenced by SFP. I also have not commented on them here because 1) they lacked relevance because 2) they lacked any evidence to actually discuss. Many of the threads he uses for evidence...contain absolutely no evidence. Those threads are filled with second and third hand hearsay on engines that were never disassembled, let alone photographed, or root caused for failure. Much of the conversations are simply "I think it's X" or "my dealer told me Y" -- even though the dealer never disassembled the motor and simply replaced it with a long/short block from BMW. That's an extremely low threashold of proof that is now incorrectly being considered as iron clad evidence in this discussion. In all of those threads, I only saw one example that related to this discussion as both 1) bearing related, and 2) had any evidence. The main bearing case was very close, but without looking at it further, I'm ambivalent whether it should be included or excluded.
To sum it up, basically everything he keeps bringing up doesn't contradict me because it's not what I've been talking about in the first place. Therefore these differences will always be irreconcscileable as long as I keep talking about apples and he keeps talking about oranges. We should all be able to agree when we see a thread that says his valve spring broke, that it doesn't belong in this discussion. Last edited by regular guy; 11-22-2013 at 01:32 AM.. |
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11-22-2013, 01:26 AM | #1099 | |
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These are serious question you need to answer before your theory can even begin to be accepted. Just add these to the other 10+ unanswered questions. -- Patiently awaiting some real answers -- Last edited by regular guy; 11-22-2013 at 01:35 AM.. |
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11-22-2013, 03:51 AM | #1100 | |
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"The first one or two blown motors showed up on bone stock M3's as well. These cars were totally stock with very low mileage. As time went on, more and more blown motors showed up, again NA motors with low miles. It seemed if you made it past 25,000 miles, then your motor would likely survive the warranty period. Various theories were discussed to explain this phenomena. The theories ranged from inferior oil pump design to bearing clearance issues." *You* referenced blown motors at the start but now want to exclude them because the actual low failure rate doesn't suit your theory. If the expected outcome of a tight rod bearing clearance is not an eventual failure then there is no problem and the bearing clearance is fine....and what better ultimate indicator of a rod bearing problem is there is, if its not the failed engine rate? To be fair I didn't made a forensic analysis of the engines listed in the registry of failed engines. I worked on a simple principle...if a reason was given for the failure other than rod bearing, I noted it. All other failures (specific and non specific) were listed as a rod bearing failure (ie the rod bearing failure rate could be lower but unlikely to be much higher - of the sample in question). Last edited by SenorFunkyPants; 11-22-2013 at 09:44 AM.. Reason: Clarity |
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