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      08-21-2012, 08:07 PM   #67
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Originally Posted by bruce.augenstein@comcast. View Post
On the one hand, I genuinely appreciate this informational nugget, as my dated knowledge would've said five or six microns. On the other hand, sub-micron tolerances in this area may well take another 25 years...

Be that as it may, however, even three microns is a far cry from your sub-micron comment, and my original note was about cylinder to cylinder and piston to piston variation - not crankshafts.
I said "microns or smaller" and that is absolutely correct. I never specifically stated "sub-micon" but I can see how one can interpret what I wrote to mean that.

Originally Posted by bruce.augenstein@comcast. View Post
On the contrary. It would in fact be difficult (read: expensive). You would have to measure each piston to essentially exactitude, then store it in one of hundreds of buckets, then measure each cylinder to exactitude, then go and retrieve an appropriate piston... Expensive.
Again I doubt that anyone is doing this particular type of matching today by machine. However, engine parts are generally 100% inspected already, it is done by robots and is automated during machining. It would not take much more effort for some level of parts bin-ing and matching. If there was a compelling reason to do so someone obviously will do it. It certainly would not take 100's of bin sizes either. If there was a benefit to be had you could probably realize a good portion of the benefit with 10 times fewer bins.

Originally Posted by bruce.augenstein@comcast. View Post
I am going to take this as just another of your thoughtless comments, as opposed to a deliberate insult.
It is neither, take it how you like.

Originally Posted by bruce.augenstein@comcast. View Post
In point of fact our disagreement is based on the fact that I know it's NOT all about the money.

Mercedes has built those 6.2 liter engines by the thousands, since they've put that engine into just about everything except the Smart Car. There was clearly enough volume there to justify the automated tooling (a good deal more volume than exists with the S65), yet they went with hand assembly - at least as far as fitting pistons goes.

I believe they did this to get better piston to cylinder wall tolerances, with whatever benefit that provides them.
Are you absolutely positive this part of the process is entirely done by hand for the entire production volume of this engine? Can you prove that or do you have any solid evidence of it at all. Other than a silly signature on the engine...

What are these benefits exactly? One reason (among many) we have rings is for less sensitivity to piston/cylinder fit.

Come on get with the program. You think that in regards to piston/bore fit that hand measurements, hand bin-ing and hand installation is less expensive in these volumes than doing so by machine? That just doesn't make sense.

There are a few possibilities here from my perspective, again somewhat speculative, since I have no first hand/second hand knowledge of this engine assembly process. In most automotive assembly processes, body, engine or otherwise there are sub-processes that can be done less expensively by hand as opposed to by machine. Thus some processes for this engine are done by machine, some by hand. MB then uses this as a marketing opportunity to appeal to the outdated notion that by hand is somehow high-end, magical or better.

I highly doubt that the entire volume production of this MB engine has hand inspected, hand sorted and hand installed pistons purely to improve the quality or performance of the engine. In fact, even without direct knowledge, I would be willing to bet this is not the case. Money drives just about everything and it will be driving this as well.

Originally Posted by bruce.augenstein@comcast. View Post
PS - By the way, your childlike faith in the M Group's ability to provide sub-micron tolerances in the S65 is touching - but I'll need some proof, please.
Ease up on the insults, especially when they are 100% without basis. I have no evidence, do not believe and did not state that BMW M is doing anything appreciably any different than MB here. I also never said BMW M is doing anything sub-micron. GET YOUR FACTS and READING ABILITY SORTED OUT. Perhaps the senility of your old age is affecting your reading comprehension here? What I said is the BMW M (and BMW in general) has many single digit micron tolerances and this follows simply because the S52 already has some and improvements have been made since then.
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Last edited by swamp2; 08-21-2012 at 08:14 PM.