01-23-2013, 12:59 PM | #309 | |
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01-23-2013, 03:35 PM | #310 | |
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If u work in the computer industry u'll know that when yields improve some of those binned can actually be graded higher, that's why some components can be overclocked using stock settings. Don't u think by making a detuned engine they're utilising nearly all the available production? Last edited by clarence; 01-23-2013 at 03:56 PM.. |
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01-23-2013, 03:44 PM | #311 | |
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The Q&A said in theory if u change the pistons & ECU u'll get a 28i, but they do not support that idea. |
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01-23-2013, 10:18 PM | #312 | |
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Regarding the 11:1 compression ratio (high CR) 20i engine on RWD 320i and 520i: although there is no direct evidence against the "binning" theory, at least now there is solid proof that the variance in quality is not "the only" difference between the high CR 20i engine and the 28i engine. BMW needs some limiting factors on the 20i engine so that they can preserve the differentiation between 20i and 28i engines, especially in their bread and butter segments - 3ers and 5ers. IMHO, they cleverly use the different shape of the piston head to achieve the objective - higher compression ratio subjects the engine to higher probability of knocking when adding boost, and it would be more than a small job to replace the pistons. There could be other forces at work which we may not fully understand yet, e.g. limp mode by DME software. The previous discussion among you, E90fleet, and others have greatly benefited the community in advancing the understanding about N20 platform before 320i is available in US. I myself appreciate that very much. However I think the discussion about the piston was missing previously. As to why BMW chooses to use the low-compression version of the N20 20i on X1, X3, Z4, and even x-Drive version of 320i and 520i, it would be another interesting discussion and more understanding of the platform may be discovered in that process. However it does not change the fact about the high CR 20i engine. Check realoem for the part number of the pistons in different engines and you'll know. |
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01-23-2013, 10:59 PM | #313 | |
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As to why they made 11:1 version of the 20i (remember it takes R&D resources to increase the CR of the engine due to need to redesign the pistons), I think it has more to do with efficiency gain. Limiting tuning potential is a useful by-product. As the max boost is reduced, they can increase CR w/o risk of detonation. As for the low CR version, I think we shall leave it as it is for the time being. http://www.f30post.com/forums/showth...&highlight=N20 http://www.f30post.com/forums/showth...&highlight=N20 Last edited by clarence; 01-23-2013 at 11:08 PM.. |
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01-24-2013, 08:14 AM | #314 |
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I know nothing about the N20 or the f30 but let me attempt to provide some insights from logic.
1.The n20 in '20s and 28s are mostly identical because BMW wants to reduce costs. 2.It makes sense to differ a few components to make it uneconomical for people to buy '20s and remake them as legit '28s. But not too much (as it costs more), just up to the price difference in the models. 3. Binning engines is stupid; if the differences are so large, the engines would fall apart!!! 4. You can make a '20 as fast as a 28 without changing the hardware differences, by a cheap tune. Although it is not exactly the same, the performance is. |
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01-24-2013, 08:48 AM | #315 | |
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a) Semiconductor manufacturing is much, a much, much younger technology than metal casting and machining. b) The tolerances for semiconductor performance operate on a nanometer scale, versus engine tolerances. Even for interference fit parts, tolerances are typically 0.0000 inch (ten-thousandths of an inch). There are 2540 nanometers in 0.0001 inches. So, the precision required to manufacture a semiconductor is several orders of magnitude greater than high-precision machine work. c) Binning and yields are an effect of the technology limits encountered in semiconductor manufacturing. This is not something that engineers intentionally designed in to the process. In other words, it's not desirable. If semiconductor manufacturers could eliminate binning tomorrow, they would. Why would we (humans), having the technology required to manufacture on a nanometer scale, settle for binning in something as well known, and well developed, as metal machine work? I do not accept the binning assertion on the basis that I don't believe it is necessary. Stated another way, I don't believe that BMW would have significant enough yield issues when manufacturing the N20 to necessitate binning. There is, otherwise, no justification for the binning hypothesis.
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01-24-2013, 09:19 AM | #316 | |
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Put another way, BMW would have to be the most incompetent engine builder in the automotive industry to be seeing enough variation in engine-to-engine horsepower for binning to make sense. Henry Ford probably didn't see a 33% variance in horsepower from one Model T engine to the next, so I'm pretty sure BMW isn't seeing it now building the N20 with fucking robots. |
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01-24-2013, 10:06 AM | #317 | |
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I am simply unconvinced that the variation levels in output are so substantial that this explain 20 versus 28. Far too expensive a way to determine which engines are supplied and if true it likely means that a significant number of engines go over 300 hp and others can't even get 150. That's a severe design flaw and of the many things known about BMW engines, being under-engineered is not one of their characteristics. |
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01-24-2013, 10:19 AM | #318 | |
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You are just burning fuel in a chamber, unless there is something wrong with the air input, friction is the only other thing that can eliminate from performance. If you had any siginificant friction causing this, the part would wear out and break. I mean it's not really possible unless something is malfunctioning. |
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01-24-2013, 11:35 AM | #319 |
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To be fair, and I can't believe I'm even offering any explanation for this viewpoint, Clarence isn't claiming that the variation accounts for the full difference between the engines. As far as I can tell, he's claiming that some engines, when dyno'd, do not produce the full baseline horsepower expected from the N20 240 HP version. So for example:
This is where things get janky. We must assume at this point that the engine will circle back in to some stage of the production where it is re-flashed with the 180 HP ECU package and re-run on the dyno, because we can't simply sell the 180 HP version with "just under" the output of the 240 HP version. That isn't supported by user submitted dyno evidence either. In order for the scenario described above to make any sense at all, the following conditions must be true:
I find both of these claims dubious at best. So it's either all this bullshit, or BMW simply engineered the two engines accordingly and we haven't discovered exactly what component it is that they changed yet. Which is more probable?
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01-24-2013, 12:42 PM | #320 | |
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We've already discovered long ago (early last yr to be precise) that there are 2 versions of the U0 engine - one with 11:1 compression & the other with 10:1 compression. The high compression version (fitted to most F30 & F10/11) have unique pistons as described in the Chinese article above. In fact the technical training staff from BMW China confirmed that, for the high compression version, the only physical difference between a U0 & O0 is the pistons. All other mechanical components are identical. Therefore the high compression version is always destined to be a U0 from the very first step in the assembly process. What's interesting is the low compression version. That engine, fitted to all E84, F25 & some F30s & F10/11s (namely the xDrive version & some specific markets), is identical to O0 part for part. The low compression version did use a different turbo during periods of time in late 2011 (according to ETK), but after that the turbo is the same. For this version of the N20 it's up to u to think how BMW chooses which ones have the priviledge to be a U0 & not a O0. So far nobody has posted a dyno plot of the U0 in stock form, but the Chinese article did suggest that, like the O0, the factory claims are conservative. |
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01-24-2013, 01:23 PM | #321 |
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So what happens when they're short on defect engines? Do they simply down-bin competent engines? They'd have to, because current automobile manufacturing strategies don't include stocking warehouses full of engines for no good reason. That means we should see '20i engines on the market that are fully capable of '28i output.
BMW isn't renowned for their super-short supply chains, but they're not sloppy either. The problem with binning is that it relies on a statistical distribution of yields in large runs. Microprocessors are manufactured in much larger lots than engines, so it works for them. Processors are also sold a lot like commodities. Fluctuations in pricing at at the low-end can occur independently of price changes at the high end. There are price constraints, but the defect rate in microprocessors follows a curve that is often similar to the pricing curve (until much later in production). This is not coincidence. All of this is an emergent (bottom-up) system based on the fact that microprocessor manufacturing pushes the boundaries of our best technology. This model makes no sense with automobiles where customers dictate orders. BMW can't simply release engines to market in whatever quantities they want. They have orders to fill. BMW doesn't release a batch of cars on to the market; BMW dealers order their cars just like a customer can. Imagine the difficulty in aligning the defect rate of engine design and manufacture to anticipated customer demand. If the defect rate turns out too high, BMW has to eat that loss. The price window for their car line up is too tight for them to treat their engines as commodities subject to internal supply side fluctuations. This is something they would *have* to control tightly or they'd be giving up a significant competitive advantage to every other manufacturer. The short version is that, not only does it not make sense from an engineering perspective, it doesn't make sense from a supply chain and economic perspective either. Not buying it.
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01-24-2013, 01:33 PM | #322 |
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It makes it far more complicated than it is worth it, especially given the ground assumption that inherent differences are very, very small, say in the 1% range.
It's more logical for BMW to fit different turbos and cooling (as mentioned b4) so that increasing the output of the 20i without changing these components is not recommended. Probably less than 1/20 20i's sold will be chipped so BMW would just let these guys have the free lunch that only costs them what 4-5k USD and they don't have to mess around with different components to spite the knowledgeable DIYer. |
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01-24-2013, 03:00 PM | #323 | |
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There will be no impact to the supply chain etc. etc. cos, the defect rates are very likely to be lower than demand for the low compression version. It will only become a problem if the defect rates are higher than the demand as u said (unlikely in this case). Also the lead time for the engines are abt 1-1.5 mth (only 2 plants in Europe supplies the world), so they have enough time to plan production allocation. Do customers really dictate orders? Sometimes they do but sometimes that's not the case. Frequently in the past they had to subsidise certain versions or models in order to fill the production capacity (e.g. F07 in Europe & Asia). They also sometimes do release a batch of cars to the market, with certain incentives to certain importers. Last edited by clarence; 01-24-2013 at 03:14 PM.. |
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01-24-2013, 03:10 PM | #324 | |
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01-24-2013, 03:16 PM | #325 | |||
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01-24-2013, 03:41 PM | #326 | |
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We (a number of us) identified key parts for the low compression version & they have the same part number. The software is of course not the same (but the DME part number is identical). The "identical part" came, again, from the BMW China tech rep from the article. He explicitly said, when questioned, that the high compression U0 & low compression O0 is identical in every part except for the pistons. |
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01-24-2013, 03:57 PM | #327 |
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Clarence, the biggest problem with your binning argument is that it doesn't explain at all why tuners are not able to get the same level of power out of x20i as the x28i ON THE DYNO.
I am sure some level of binning exist in any manufacturing. But, let's think about this hypothetical binning of yours. The ones that pass the test are the ones that can generate ~240HP for a reasonable amount of mileage, say 100K, without blowing up. And the ones that fail are the ones that can't generate the same power at the same boost, so they would detune it and sell it as x20i. BUT, this does not mean that the failed ones would blow up as soon as you up the boost to 328i level, even if your conjecture was true. It could mean that when the boost gets turned up, the longevity of the engine will fall below the acceptable level. But that alone will most definitely not stop a tuner from bumping up the power and selling the reflash. No aftermarket company is going to do a 100k mile test to see if the tune holds up. Now, it could be that BMW has put extra guard against high boost in the software to prevent people from pushing these "defective" engines too far. But if that is the case, then the direct reason for the tuners' supposed inability to get the power is NOT the quality of the engine, but the software. It could be that once they crack the software, the owners with the tune may find that their engines break down after 50k miles. But that hasn't happened, apparently because people can't make big power out of it. This very strongly suggests that binning cannot be the only, and even the most relevant, explanation for this problem. |
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01-24-2013, 04:31 PM | #328 | ||
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01-24-2013, 05:58 PM | #329 |
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I am a Saab guy. I am used to this. There was the 2.0t and 2.0T, nearly identical engines with differing outputs. Same with the b235r and b235e which had different valves and or pistons besides the ecu tune.
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01-24-2013, 09:59 PM | #330 | |
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BMW offers turbo diesel engines that are of a single family but in various different outputs for many years, so if indeed that's whts going on then they're not new to the game (& neither is for other European makes). There are bound to be variations in outputs, however small, so it's just a way of cost savings. |
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