Official S65 Bearing Specification/Clearance Wiki

[BMRLVR]

If the DME has a knock control it will not matter the AKI of the fuel. If it is able to pull timing it is able to pull timing regardless of the AKI. The DME has no idea what grade of fuel is in the tank, it just senses knock and adjusts timing accordingly. If it were the case that the DME could not adjust timing on fuel that was below AKI if 90, people in hot climates would be really screwed. Knock/detonation is caused by heat/pressure in the cylinder igniting the fuel before the spark plug fires. Saying the DME can't adjust with fuel below 90 AKI is no different than saying the the DME is unable to control knock at temperatures above a certain level.

The knock system used by the MSS60 actually measures the PPP or peak pressure point in each cylinder by measuring the resistance across the plug gap using 400v. Since it is actively measuring the pressure in each cylinder on every cycle the AKI of the fuel is irrelevant.

[swamp2]

Originally Posted by swamp2

Why is it so absolutely, postively inconceivable that BMW may have screwed up hardware or software in their anti-knock system but at the same time is very reasonable, in fact probable that BMW did entirely "screw the pooch" with regards to something like bearing clearance ratios (which you claim (and I disagree with) have not changed in 50 years).

Originally Posted by regular guy

That's still a misinterpretation and you're still reading too much into what I've said.

I disagree. Although you may not be so far down the spectrum of thought that BMW screwed up clearances and screwed them up big time. I feel that your direct statements sometimes indicate you feel this. I've quoted those statements in the past. Other times you seem to fall into the camp that chris719 summarized that I also mentioned here long ago

Originally Posted by chris719

IMO, this is an intentional design consequence that gave some cost, emissions, or power advantage, and BMW does not really give a damn if your engine dies out of warranty.

I guess that my original question of why it is so much more "likely" that BMW screwed up one thing over another still stands. Perhaps that question is more appropriately addressed to those that staunchly believe BMW screwed up clearances big time but also believe their anti-knock hardware and software (a much more complex beast for sure than a single number representing a clearance) is above and beyond any line of questioning.

[Cool Steel]

Originally Posted by speedaddictM3

I'm not making any expensive decisions. I'll do my first oil analysis soon and switch to thinner oil. If the oil analysis is good I'll take my chances and keep the car, but definitely no stroking out or supercharging. If the analysis reveals higher levels of lead or copper I won't bother swapping out the bearings. I'll dump the car and get something better like a Z06 Vette or GTR instead.

This is logic...since there will never be a conclusion on this topic...
However, without the ability to ever supercharge due to the risk, or do any meaningful upgrades, boredom will soon set in. Also, since we are all now seeing the truth, that the M3 is a high priced car with a subpar engine relative to the Vette/Camaro, ....I think a jump to your final sentence is in order....

[catpat8000]

Originally Posted by BMRLVR

If the DME has a knock control it will not matter the AKI of the fuel. If it is able to pull timing it is able to pull timing regardless of the AKI. The DME has no idea what grade of fuel is in the tank, it just senses knock and adjusts timing accordingly. If it were the case that the DME could not adjust timing on fuel that was below AKI if 90, people in hot climates would be really screwed. Knock/detonation is caused by heat/pressure in the cylinder igniting the fuel before the spark plug fires. Saying the DME can't adjust with fuel below 90 AKI is no different than saying the the DME is unable to control knock at temperatures above a certain level.

What you said above is basically what I was saying in my question to SFP. However it is not hard to imagine a scenario in which the ECU cannot pull timing enough to prevent knock. For example, and just speaking hypothetically, imagine a hot engine with high compression and very poor fuel. Once running, even if spark is cut off entirely, it may still continue to pre-ignite. In such a case, it could be said that the ECU couldn't compensate for fuel of such poor quality.

So it seems to me that the ECU cannot compensate for any possible situation. There must be a limit to its ability and perhaps SFP is saying he heard that the limit is fuel with anti-knock of 90 under certain ambient conditions.

That is what I am questioning because I find it hard to believe that the ECU couldn't compensate for 90 Aki.

[speedaddictM3]

Originally Posted by SenorFunkyPants

Regarding software fixes. AIUI it would be a massive enterprise to apply a software fix to the ECU map to expand the range of permissible fuels to include down to 87 octane...the map would end up prohibitively large.

FYI, the 5L V8 in the Mustang, in addition to producing more power and torque than the S65 engine, is perfectly capable and in fact approved from Ford itself to accept any octane rating all the way down to 87 without any risk of mechanical damage or voiding warranty. And since the Mustang doesn't have a large mainframe supercomputer stuffed away in its trunk, I assume the new software to accomodate more fuels isn't nearly the prohibitively large sophisticated computer program you make it sound like.

[FogCityM3]

Wasn't Ford also saying the Coyote engine ECU wasn't sophisticated enough to go beyond 7,500 rpm safely? Lower compression, higher displacement and lower RPMs are more forgiving with lower quality fuels.

Originally Posted by speedaddictM3

FYI, the 5L V8 in the Mustang, in addition to producing more power and torque than the S65 engine, is perfectly capable and in fact approved from Ford itself to accept any octane rating all the way down to 87 without any risk of mechanical damage or voiding warranty. And since the Mustang doesn't have a large mainframe supercomputer stuffed away in its trunk, I assume the new software to accomodate more fuels isn't nearly the prohibitively large sophisticated computer program you make it sound like.

[speedaddictM3]

Originally Posted by FogCityM3

Wasn't Ford also saying the Coyote engine ECU wasn't sophisticated enough to go beyond 7,500 rpm safely?

Never heard of that before. I'm sure the ECU is hard wired to limit the engine to 7500 rpm. not sure if the cause is lack of "sophistication", whatever that means. Engine redlines are usually limited more due to mechanical concerns and problems than software issues.

Lower compression, higher displacement and lower RPMs are more forgiving with lower quality fuels.

Well if we assume that all the bearing issues are caused by detonation (and I don't think that's the case), then maybe bmw should have made a lower compression higher displacement S65 engine then, especially since most of us don't have 110 octane racing fuel in our gas stations to prevent knock and increase reliability.

[MWM3]

60 pages deep....so what have we concluded?

[Someone?]

Originally Posted by MWM3

60 pages deep....so what have we concluded?

Ive concluded that the 2nd(1ST FOR A LONG TIME) most profitable car compnay in the world are a bunch of sorry fucks that couldn't simply make the correct size bearings, pretty F N simple, they just didnt want to pay for earlier mistakes, But they should get a class action lawsuit for 1000 of customers.

[swamp2]

Originally Posted by Yellow Snow

It might be worth doing yourself a favour and showing this complete thread to a genuine expert in high performance passenger engine design.

You will be fascinated by some of their comments.

Please do share. Heck, I don't even care if the fellow is not willing to be named. Nothing wrong with privacy/ethics/conflict of interest concerns whatever they may be. Perhaps just his exact position and/or company can be named (with no risk of identification)? I've questioned the so called experts here about their experience and credentials and have gotten basically zip. This is confounded by conflicting information from Clevite personnel.

Please share!

[chris719]

As a software engineer, I can tell you nothing about the software in the DME is "large" or that complex. The Freescale MPC563 microcontrollers used in the MSS60 can only hold 512 KB of executable code in it's internal flash and the device has 32 KB of RAM. They also only run at a max clock speed of 66 MHz. That makes it a "big MCU" but it's still an embedded device.

It's also doubtful the maps are lookup tables for each fuel grade. They could easily handle 87 from a software standpoint if the physics and mechanical side of it worked out.

[regular guy]

Originally Posted by swamp2

I guess that my original question of why it is so much more "likely" that BMW screwed up one thing over another still stands. Perhaps that question is more appropriately addressed to those that staunchly believe BMW screwed up clearances big time but also believe their anti-knock hardware and software (a much more complex beast for sure than a single number representing a clearance) is above and beyond any line of questioning.

I'd like to see somebody establish that the wear patterns on the bearings are detonation related, not just for one engine but for many of them (S65 and S85). I personally wouldn't consider the ECU, it's programming, and anti-knock hardware (which are the spark plugs) as suspects until a connection or even a reasonable pathology for that wear patterns can be established. I think you're asking for the car before the horse.

[catpat8000]

Originally Posted by MWM3

60 pages deep....so what have we concluded?

Not much but we're having fun. As far as I can tell, nothing has changed since this summary 15 pages and two weeks ago except that there are actually fewer known failures than was believed then.

http://www.m3post.com/forums/showthr...5#post14981605

[aussiem3]

Originally Posted by MWM3

60 pages deep....so what have we concluded?

I am wright you're wrong ... that's what gone now. It's not about bearing or detonation or oil anymore.

[swamp2]

Originally Posted by catpat8000

Not much but we're having fun. As far as I can tell, nothing has changed since this summary 15 pages and two weeks ago except that there are actually fewer known failures than was believed then.

http://www.m3post.com/forums/showthr...5#post14981605

Ha, spot on... This post and the self referenced one as well.

[swamp2]

Originally Posted by regular guy

I'd like to see somebody establish that the wear patterns on the bearings are detonation related, not just for one engine but for many of them (S65 and S85). I personally wouldn't consider the ECU, it's programming, and anti-knock hardware (which are the spark plugs) as suspects until a connection or even a reasonable pathology for that wear patterns can be established. I think you're asking for the car before the horse.

I know it appears to be mired in some question of leading the witness, but your "star witness" has already said detonation is a possible cause.

The quicker and more prone we as a group are of rejecting one particular hypothesis outright and doing so very early in the game, especially when most if not all of us lack the expertise required to do so, then the sooner we will be not following a basic scientific process and we will radically increase our chances of being incorrect.

What do you have to say to folks like this (there have been many here in the thread, but this one was just a few posts back):

Originally Posted by ibmike

Ive concluded that the 2nd...most profitable car compnay in the world are a bunch of sorry fucks that couldn't simply make the correct size bearings, pretty F N simple...

Have you, BMRLVR and/or kawasaki contributed to this persons firm and absolutist conclusion on the issue? I think it is also very safe to say that you largely do not share this persons opinion?

[regular guy]

Originally Posted by swamp2

However, how many folks are doing bottom end tear downs of either unmodded or modded N54's/N55's due to a suspicion of bearing wear? It also raises the question, what are the clearance ratios for these engines?

Model	Engine	Max RPM	Oil	Min(mm)	Avg(mm)	Max(mm)	Min(SAE)	Avg(SAE)	Max(SAE)	Size(mm)	Ratio(mm)	Size(SAE)	Ratio(SAE)	RPM-Clr Ratio
E92 335	N54 (Main)	7000	0-30 to 5W40	0.020	0.033	0.046	0.00079	0.00130	0.00181	55.996	0.0006	2.205	0.00059	1188
E92 335	N54 (Rod)	7000	0-30 to 5W40	0.025	0.048	0.070	0.00098	0.00187	0.00276	50.000	0.0010	1.969	0.00095	737
E92 M3	S65 (Main)	8400	10W60	0.029	0.037	0.046	0.00115	0.00144	0.00180	59.984	0.0006	2.362	0.00061	1378
E92 M3	S65 (Rod)	8400	10W60	0.028	0.033	0.048	0.00110	0.00128	0.00189	51.984	0.0006	2.047	0.00063	1343

[swamp2]

^ Good info, thanks. In short slightly tighter mains and looser rods but both violate the Clevite "rules of thumb". This leads to the obvious follow up questions

1. Is it solely and oil issues that allows such tolerances. Even with the oil choice it still violates by s significant amount the Clevite "rule of thumb".
2. How many folks are disassembling the bottom ends of otherwise normally running N54/N55 engines? If that number is little to none this doesn't allow us to conclude much.

Of course the redline, overall engine architecture (I6 vs. V8) and different designs (weights and moments of inertia) for the pistons and rods are also very confounding factors even if this could point toward some conclusion.

[regular guy]

Originally Posted by swamp2

I know it appears to be mired in some question of leading the witness, but your "star witness" has already said detonation is a possible cause.

This is true. That admission came after about four emails with the caveat it wasn't considered very likely.

The quicker and more prone we as a group are of rejecting one particular hypothesis outright and doing so very early in the game, especially when most if not all of us lack the expertise required to do so, then the sooner we will be not following a basic scientific process and we will radically increase our chances of being incorrect.

Good point. But I think there needs to be some proof at the very least some path to proof, or some connection to emperical evidence. I dont think there's even a connection to emperical evidence yet. I'm just not the type of person who will believe that the mere presense of low octane fuel in a particular regional area, whether used or not, is good enough. According to SFP, the mere presense of the fuel is enough to assume the owner accidentally used it one time, and that one time use is enough to explain the bearing wear patterns. That theory will never have credibility with any scientifically-minded person, and dare I say it doesn't have any credibility with you either. But that's what's being alleged here without any proof or emperical evidence.

What do you have to say to folks like this (there have been many here in the thread, but this one was just a few posts back):

I believe in posting all the data I collect, good and bad. I believe in letting each person make up their own mind. I also believe they are the only person responsible for their own beliefs and conclusions.

Have you, BMRLVR and/or kawasaki contributed to this persons firm and absolutist conclusion on the issue? I think it is also very safe to say that you largely do not share this persons opinion?

I thought the comment was totally sarcastic and not meant to reflect a true opinion. That's how I interpreted it when I read it.

[regular guy]

Originally Posted by swamp2

^ Good info, thanks. In short slightly tighter mains and looser rods but both violate the Clevite "rules of thumb". This leads to the obvious follow up questions

1. Is it solely and oil issues that allows such tolerances. Even with the oil choice it still violates by s significant amount the Clevite "rule of thumb".
2. How many folks are disassembling the bottom ends of otherwise normally running N54/N55 engines? If that number is little to none this doesn't allow us to conclude much.

Of course the redline, overall engine architecture (I6 vs. V8) and different designs (weights and moments of inertia) for the pistons and rods are also very confounding factors even if this could point toward some conclusion.

I wonder sometimes whether mains SHOULD be tighter than rods. Since mains don't reciprocate, sometimes I think mains might be OK tighter than the Clevite rule. But I'm not an engine expert here either.

[Yellow Snow]

Has anyone logged what's happening in the first minutes cold start phase where the kangarooing is rife on low grade fuel? That's where the bearings take a beating.

[SenorFunkyPants]

Originally Posted by catpat8000

So it seems to me that the ECU cannot compensate for any possible situation. There must be a limit to its ability and perhaps SFP is saying he heard that the limit is fuel with anti-knock of 90 under certain ambient conditions.
That is what I am questioning because I find it hard to believe that the ECU couldn't compensate for 90 Aki.

A few days ago I came across a post by Mike Benvo that referenced a couple of things that have since come up.
Firstly Mike noted that there was a limit to the amount of pull that the ECU could make in response to detonation and that 90-91 aki was the ballpark lowest level that the ECU was programmed for. Noting that the ECU doesn't know or care what octane fuel is being used, it simply reacts to the data provided by the ionic current sensing system...and that environmental conditions would also have a significant effect.
Secondly, Mike was specifically asked why not just map the range down to cover 87 aki and the reply was it would be technically too difficult (it was explained better than that but that was the essence of it).
Further confirmation is provided by BMW who specifically warn against using fuel below 91 aki as it could lead to engine damage...and the common sense point that if the S65 could indeed handle 87 aki octane fuel without consequence then this would be a positive selling point.
Again note that I am not touting this as "the cause" of high bearing wear and engine failures just that it is most likely a factor in some cases.

For posters who question the very idea that any M3 owners would use 87 aki fuel then there is this:
"So i'm filling up my tank yesterday, and I see another guy with an M3 also filling up at the pump next to me. I couldnt help but notice he was putting 87 octane in his car (I always use 91). So I asked him why he uses 87. He said that he "used to use 91 and since he switched he cant tell any difference in performance, and it is top tier gas"
http://www.m3post.com/forums/showthr...hlight=pinging