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      08-22-2012, 05:39 PM   #75
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Originally Posted by swamp2 View Post
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.
First of all, my initial participation in this string was in regard to how hand fitting of pistons could be of benefit, even in an automated world. That's all. My subsequent participation in this string was also in that specific area, except where I responded to your 3-micron crank journal quote - which was off (my) narrow topic.

Second, you had your chance to back off your micron or smaller position back in note 64. When I mentioned that you were dreaming, you said: "Sorry, wrong." Too late to weasel out now.

Originally Posted by swamp2 View Post
...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...
I am absolutely not positive, meaning I have no direct knowledge of this. When the engine was introduced, I read a number of reports in regard to this being the first AMG-only engine, and that it was hand assembled. Since then, I haven't read anything about this version or that version being machine assembled, and I assume there would've been something if that indeed had become the case. Again, no personal knowledge of this, but that's the way to bet, I think.

Originally Posted by swamp2 View Post
What are these benefits exactly? One reason (among many) we have rings is for less sensitivity to piston/cylinder fit.
As I've already mentioned, benefits include more power, a smoother engine and perhaps slightly better mileage. To this I would add the possibility of better endurance under duress. Anecdotally, I remember when the Corvettes and Porsches were going at it hammer and tongs in "showroom stock" racing back in the eighties in the U.S. You weren't allowed to do any hand machining to the engine, so the Vette guys would get a bunch of pistons and hand fit them to individual cylinders. This in an effort to get a bit more power (they were way down on that) and better endurance. Generally speaking, keeping things on the loose side of the spec meant more power.

I'd bet the Porsche guys were testing blow-off valve after blow-off valve as well, looking for the ones that would maintain the highest permissable boost within spec.

Originally Posted by swamp2 View Post
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.
As I've already mentioned in this string, hand assembly and big volumes don't work from a cost perspective.

To repeat myself, the other reason for hand assembly is performance. As a for instance, you can bet that every 911, every M3, every 458 and anything else competing in the ALMS has a lovingly hand built engine.

Originally Posted by swamp2 View Post
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.
You and I disagree that hand assembly is an outdated notion.

As to Mercedes dishonesty, you have no direct knowledge of that, and of course you don't believe that their 6.2 liter engine weighs the stated 436 pounds, either. So we know that you have something of an attitude about MB, therefore dropping your credibility in regard to MB issues down to near zero.

Originally Posted by swamp2 View Post
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.
We'll agree to disagree about money driving this entirely. More on that in a PS, below.

I personally feel that improved quality and performance is the chief reason for them hand assembling the 6.2, but "improved quality and performance" is a statement that needs filling out, or a better definition, if you will.

Where are they starting from? This is AMG's first engine, after all, and what if they've got a bit of a glitch somewhere, sufficient to necessitate hand assembly, or at least to make that the preferred method?

Originally Posted by swamp2 View Post
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.
Gee, you're cute when you're angry.

As mentioned, you had the ability to back off sub-micron in note 64, and didn't. Don't try to weasel out now.

Finally, I've kept my hand-built comments narrowed to custom fitting of pistons, and expect that normal folks reading this string will easily understand those comments. Particularly the OP.


PS - In regard to Chevrolet, they hand assemble Corvette engines fitted to the Grand Sport stick cars, all Z06s and all ZR-1s. A year or so back, I asked a Corvette engineer (during the Corvettes at Carlisle massive show) about why they did this. He said that they got a bit of power out of hand assembly, but mostly they did it because from their perspective, these particular models were going to get beaten like a red headed step child, and would last better under those conditions.

I mention this because it's another reason why manufacturers may do this, and this subject is not quite as cut and dry as you seem to think.

Last edited by bruce.augenstein@comcast.; 08-22-2012 at 06:25 PM. Reason: Spelling