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      01-24-2013, 11:04 PM   #331
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about the mpg

Mpg will be one of the important reason to sell this car and I don't see this one will have the same numbers with the 328i. If you compare the l/100km numbers of 320i and 328i in Europe, you'll see 320i is almost 10 percent more efficient in each category. Therefore, don't be surprised if you see 35 or 36 mpg when BMW announce the official numbers.
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      01-25-2013, 12:01 AM   #332
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Originally Posted by Propagator View Post
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.
There are 2 versions of the U0 engine (U0 is 20i's state of tune whereas O0 is 28i's state of tune) - high compression version & low compression version. The HC version has comp ratio of 11:1 whereas the LC version has comp ratio of 10:1 (i.e. same as O0). As confirmed by BMW China tech staff, the HC version have different piston crowns. They also confirmed that detonation will occur if the HC engine is ran at O0's (i.e. 28i's) level of boost.
Hence tuners cannot get O0's level of output using this version of U0 with just a piggy-back (AFAIK the DME on the N20 has not been cracked). Major upgrades need to be done to reach around 235ps (confirmed by poster several pages back).

The LC version of the U0 can theoretically be made to output at O0's level of output by running at O0's level of boost (or close to it's rated output if binned due to some "defect"), but it seems no tuner have tried to distinguish between these 2 versions of U0. There can be several reasons for this, e.g. this engine is only fitted to E84 & F25 during certain production dates, & for certain production dates it also had a different turbo, so it may be difficult to find a development car. As BMW themselves don't disclose why each of these LC engines are classified as U0 rather than O0, the tuners had to play safe. Again as the DME has not been cracked so all they can offer is a piggy-back.

The testing u mentioned is already done during prototyping stage, wht they do at the plant is a dyno run. A failure can be caused by sth as simple as the engine missing a few Nm's compared with the rated torque at idling speed.
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      01-25-2013, 12:04 AM   #333
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Originally Posted by Jamesons Viggen View Post
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.
Yes, as do Volvo, Ford, GM, VAG, Daimler-Benz etc etc.
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      01-25-2013, 01:58 AM   #334
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So according to your theory BMW has a shit of a manufacturing line that it can't control tolerances well so much so that a whole line of vehicles (the 20i) is spawned.

Since u say the failure rate is so high then what happens to the turbocharged 4.4 in M cars and the 35i engines? BMW has to make 2 or 3 engines and throw away 1-2 engines just to make a car because their detect rate is soooo high?
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      01-25-2013, 02:34 AM   #335
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That's central to my point. For what other engines does BMW use this binning approach? Is this something new? I've never heard of it applied to complex assemblies like an entire engine. The output is strictly a sum of all the parts, and those parts are scrutinized throughout the process for the very purpose of eliminating final stage anomalies.
all lit up over the binning approach for something as complex as an engine.
This. Binning is only appropriate for individual components, like LEDs where one cannot further differentiate due to inherent limitations in manufacturing process.
This is not the case with pistons, blocks. Each bit would be measured to be acceptable, after which they are randomly fitted together and the differences made up by seals and oil.
If when the engine is put together it does not reach the desired level of output, it is 'defective' because something clearily is wrong - I do not think they would still use this engine as the problem would cause it to break down sooner or later.
Overall, if the spread of outputs on engines is so large, something is clearily wrong with the whole process and none of the engines I would call reliable.

Sum: Binning only for finest manufacturable component
Engines and other assembled machines should not be binned as this is indicative of major manufacturing problem (as they should fit together well)
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      01-25-2013, 02:39 AM   #336
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As you pointed out, since the computer stuff is so complicated now, they can just stop people from boosting it there, since it would take a Pentagon hacker genius to crack it. And save costs by no physical differentiation.
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      01-25-2013, 04:00 AM   #337
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Originally Posted by grimlock View Post
As you pointed out, since the computer stuff is so complicated now, they can just stop people from boosting it there, since it would take a Pentagon hacker genius to crack it. And save costs by no physical differentiation.
This exactLy. In order to streamline the manufacturing process the limit will be in the software. Having 2 types of production lines for the 20i n 28i is too costly.
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      01-25-2013, 04:58 AM   #338
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For those who do not believe in binning, pls be constructive & put forward ur ideas as to how BMW decides to label which of their low compression N20's as U0's & which ones as O0's. Don't know is not an answer & "there must be sth different" is also not valid (cos already confirmed low compression U0 is part for part identical to O0).

Also, power variation between identical engines is not fantasy. On Feb 2013 issue of Automobile, they did a comparison test between an Alpina B7 and an Audi S8. They put both of those cars on the dyno. The Alpina underperformed significantly when compared to factory specs. This is after a 20% drivetrain loss allowance. Don't forget BMW made those engines specially for Alpina.

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      01-25-2013, 05:04 AM   #339
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Originally Posted by grimlock View Post
As you pointed out, since the computer stuff is so complicated now, they can just stop people from boosting it there, since it would take a Pentagon hacker genius to crack it. And save costs by no physical differentiation.
No matter how secure the software is, the DME must take readings from sensors in order to detect operation parameters. The tuners boost power by putting a piggy-back module which takes the readings from the sensors & tries to fool the DME by processing the data.
BMW acknowledges this fact & even provides full drivetrain warranty for piggy-backs made by AC Schnitzer (in Europe only).
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      01-25-2013, 05:29 AM   #340
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As you pointed out, since the computer stuff is so complicated now, they can just stop people from boosting it there, since it would take a Pentagon hacker genius to crack it. And save costs by no physical differentiation.
I tend to subscribe to the view that there are other mechanisms controlled by DME software that limit the output of the 20i engines, so that physical differentiation or binning is not necessary. We may not fully understand what are the mechanisms and how they work, but the blow-off valve is likely to be one of possibilities.

In the Chinese article, the author also offered his personal experience with boost level as measured by p3car. In a 320i the BOV is effected at around 0.5par, while in a 328Li(yes they have long wheelbase version of the 3-series in China) the BOV is not effected until around 1.0par. For me this sounds like a very possible way to limit the output of the 20i engine without any variance in the quality of the engine itself. Until the DME encryption is cracked the limitation will always be there.
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      01-25-2013, 05:46 AM   #341
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I tend to subscribe to the view that there are other mechanisms controlled by DME software that limit the output of the 20i engines, so that physical differentiation or binning is not necessary.
The purpose of binning is not to limit the power of the engine but to choose which one becomes a 20i & which one remains a 28i (low compression version only). When it becomes a U0 it'll have U0 specific software.

The max boost of the U0 is naturally lower than the O0 as a.) it is to limit the power output & b.) prevent detonation on the high compression version U0. The only physical differentiation between high compression version U0 & O0 is the pistons. As before, they can increase efficiency of the engine by increasing compression as the max boost is lowered to a level where detonation will not occur. So the main aim of making a high compression version of the U0 N20 is to increase efficiency, limiting tuning potential is a useful by-product.

Last edited by clarence; 01-25-2013 at 06:00 AM.
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      01-25-2013, 05:58 AM   #342
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The purpose of binning is not to limit the power of the engine but to choose which one becomes a 20i & which one remains a 28i (low compression version only). When it becomes a U0 it'll have U0 specific software.
Sorry to be straight-forward, but you seem to be making a circular argument, like circular reference in Excel... You assume that 20i and 28i engines need to be differentiated hardware-wise, so that binning is necessary.

However I guess what I'm saying (and many others if I understand correctly) is that hardware-wise the 20i and 28i can be simply identical (save for the piston crown in the high CR version). BMW uses other software-controlled mechanism(s) to differentiate the two versions.
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      01-25-2013, 06:19 AM   #343
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Originally Posted by f11tw View Post
Sorry to be straight-forward, but you seem to be making a circular argument, like circular reference in Excel... You assume that 20i and 28i engines need to be differentiated hardware-wise, so that binning is necessary.

However I guess what I'm saying (and many others if I understand correctly) is that hardware-wise the 20i and 28i can be simply identical (save for the piston crown in the high CR version). BMW uses other software-controlled mechanism(s) to differentiate the two versions.
I think u've misunderstood wht I've said. If the U0 & O0 are already differentiated hardware wise (as in the case of high compression version), no binning is necessary as those engines are destined to be U0 right from the start.

When the U0 & O0 are identical part-for-part (i.e. low compression version U0), they have to use some method to physically select particular engines to be U0 & others to be O0 (cos they're identical). After they've selected certain particular engines then they apply the software to differential the otherwise identical engines. Binning is the method used to select which low compression (i.e. identical) engines are to have the U0 software installed & which ones have the O0 software installed. It isn't a circular argument cos binning is only used as a method for selection when the engines are built using identical parts.
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      01-25-2013, 06:46 AM   #344
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Originally Posted by clarence View Post
When the U0 & O0 are identical part-for-part (i.e. low compression version U0), they have to use some method to physically select particular engines to be U0 & others to be O0 (cos they're identical). After they've selected certain particular engines then they apply the software to differential the otherwise identical engines. Binning is the method used to select which low compression (i.e. identical) engines are to have the U0 software installed & which ones have the O0 software installed. It isn't a circular argument cos binning is only used as a method for selection when the engines are built using identical parts.
Thank you, clarence. I think I got your point. Let me ask you two question then:
1. Do you assume that there is such selection process as you described above, or you know for a fact that such selection process exists in BMW's manufacturing process?
2. You mentioned that they apply the software to differentiate the "otherwise identical engines". Do you see a possibility that without the binning process the same purpose can still be achieved?
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      01-25-2013, 07:09 AM   #345
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Thank you, clarence. I think I got your point. Let me ask you two question then:
1. Do you assume that there is such selection process as you described above, or you know for a fact that such selection process exists in BMW's manufacturing process?
2. You mentioned that they apply the software to differentiate the "otherwise identical engines". Do you see a possibility that without the binning process the same purpose can still be achieved?
1.) Yes cos they cannot just select engines randomly, there must be a valid & logical method used to select the engines. As each engine produced will not produce exactly the same power as the next one (i.e. some variances will exist, however low the %), it is only logical for them to detune those not so good ones as a U0 (rather than detune the best ones & give 28i customers not so good ones).

2.) Using software to differentiate power output & binning are 2 different matters. Binning is the selection of engines to be "differentiated" & software installation only comes after this selection. Of course they can just use software to detune the engines if they don't bin them, but the binning process itself is used for selection rather than the actual detuning operation. If they detune the engines randomly then it will introduce problems. Plus BMW runs every engine produced on the bench for QC purpose, so they already have all the relevant data needed for binning. So no, that's the only method I can see them using in selecting which engine is to be detuned or not.
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      01-25-2013, 08:59 AM   #346
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1.) Yes cos they cannot just select engines randomly, there must be a valid & logical method used to select the engines. As each engine produced will not produce exactly the same power as the next one (i.e. some variances will exist, however low the %), it is only logical for them to detune those not so good ones as a U0 (rather than detune the best ones & give 28i customers not so good ones).

2.) Using software to differentiate power output & binning are 2 different matters. Binning is the selection of engines to be "differentiated" & software installation only comes after this selection. Of course they can just use software to detune the engines if they don't bin them, but the binning process itself is used for selection rather than the actual detuning operation. If they detune the engines randomly then it will introduce problems. Plus BMW runs every engine produced on the bench for QC purpose, so they already have all the relevant data needed for binning. So no, that's the only method I can see them using in selecting which engine is to be detuned or not.
Thank you. I guess there is no point further debating on this issue. Our arguments are based on hugely differently hypothesis.

Have a good weekend.
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      01-25-2013, 10:21 AM   #347
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Quote:
Originally Posted by clarence View Post
For those who do not believe in binning, pls be constructive & put forward ur ideas as to how BMW decides to label which of their low compression N20's as U0's & which ones as O0's. Don't know is not an answer & "there must be sth different" is also not valid (cos already confirmed low compression U0 is part for part identical to O0).

Also, power variation between identical engines is not fantasy. On Feb 2013 issue of Automobile, they did a comparison test between an Alpina B7 and an Audi S8. They put both of those cars on the dyno. The Alpina underperformed significantly when compared to factory specs. This is after a 20% drivetrain loss allowance. Don't forget BMW made those engines specially for Alpina.
My theory on how they decide: They allocate the engines according to demand. There is no implicit requirement that the engines be physically different. The percentage of people who chip tune their cars is so low that it doesn't register on BMW's bottom line.

Put more specifically, BMW's risk in the scenario where the engines are identical (except software) is that some customers will by a '20i car and chip tune to get the extra horsepower. That would represent a loss of top line revenue and profit because '20i vehicles have lower MSRP and thinner margins. However, BMW have differentiated the vehicles by limiting available options, which protects them in the mass market, and only exposes them to the tuner market segment. This segment is tiny in the overall sense.

Regarding the Alpina engine. That's not a matter of production variation, that's a matter of actual output versus claimed output. This is completely unrelated to the kinds of production variations we're talking about. You can't infer statistical significance from a sample size of 1.

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Originally Posted by clarence View Post
1.) Yes cos they cannot just select engines randomly, there must be a valid & logical method used to select the engines. As each engine produced will not produce exactly the same power as the next one (i.e. some variances will exist, however low the %), it is only logical for them to detune those not so good ones as a U0 (rather than detune the best ones & give 28i customers not so good ones).

2.) Using software to differentiate power output & binning are 2 different matters. Binning is the selection of engines to be "differentiated" & software installation only comes after this selection. Of course they can just use software to detune the engines if they don't bin them, but the binning process itself is used for selection rather than the actual detuning operation. If they detune the engines randomly then it will introduce problems. Plus BMW runs every engine produced on the bench for QC purpose, so they already have all the relevant data needed for binning. So no, that's the only method I can see them using in selecting which engine is to be detuned or not.
1) Why can't they "select engines randomly"? Although I wouldn't call it random. Why not just allocate them as they come off the line? Your hypothesis stands upon two assertions:

a) That manufacturing variances in the N20 are significant enough to justify this binning approach. What I cannot wrap my head around is why the N20 would suffer from these variances, but other BMW engines do not. If all engines do suffer from these variances, then it would be considered "acceptable", and BMW would have no reason to go through the extra effort of waiting for a "defect" engine, subjecting their production process to variances in availability based on defect rate and yields.

b) That "it is only logical for them to detune those not so good ones as a U0". Why is that any more logical than simply applying software as allocation is required?

2) I think I have a pretty good understanding of your hypothesis. I disagree that "If they detune the engines randomly then it will introduce problems." What problems will be introduced?

The binning approach flies in the face of everything I know about manufacturing and supply chain management. I build software to manage the procurement process for Fortune 500 companies. I spend a lot of time with executives in charge of supply chain management, because they're often the ones doing the purchasing. Auto makers rely on just-in-time manufacturing. Cars are built as they are ordered. All the parts arrive in the order they are needed. Literally, every sub-contractor has to load the parts in the containers in the order that they will be needed for assembly. The idea is that a part should be manufactured as late in the process as possible in order to reduce the capital required to maintain parts stock.

An engine is one of the most expensive and complex components in an automobile. If BMW uses binning, it means that the availability of '20i engines is subject to defect rates and yields. That means we're dealing with statistical probabilities. When you flip a coin, there is a 50/50 chance that you'll get heads, but anyone who has flipped a coin knows that you can end up with 6 tails in a row. Or 10. Or 20. It's possible!

The question is not why, but *how* could BMW run an efficient production process if they subject their supply to this type of statistical allocation? If the next engine needed is a '20i, and they end up with six '28i capable engines in a row, what do they do with those engines? Surplus is synonymous with waste when it comes to supply chain management. Engines are too expensive to have them simply sitting around.

This is a matter of applying Occam's Razor. There must be some advantage to the binning approach versus straight forward allocation. I can't see it. I understand the idea. I'm open to considering it, but before I can agree, I need to know the reason why.
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      01-25-2013, 12:27 PM   #348
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Originally Posted by bradleyland View Post
My theory on how they decide: They allocate the engines according to demand. There is no implicit requirement that the engines be physically different. The percentage of people who chip tune their cars is so low that it doesn't register on BMW's bottom line.

Put more specifically, BMW's risk in the scenario where the engines are identical (except software) is that some customers will by a '20i car and chip tune to get the extra horsepower. That would represent a loss of top line revenue and profit because '20i vehicles have lower MSRP and thinner margins. However, BMW have differentiated the vehicles by limiting available options, which protects them in the mass market, and only exposes them to the tuner market segment. This segment is tiny in the overall sense.

Regarding the Alpina engine. That's not a matter of production variation, that's a matter of actual output versus claimed output. This is completely unrelated to the kinds of production variations we're talking about. You can't infer statistical significance from a sample size of 1.
Of course they have to allocate the engines by demand, but they also have a very clear indication as to which gets the U0 with high compression & which gets the low compression U0. BMW fits the high compression U0 to all F30s & F10/11. That is the one with different pistons & hence they have absolute control, barring defects, on how many 320is & 520is they can make according to demand. This is very clear & made explicit in the product specs provided by BMW.
The low compression U0, which has no physical difference to the O0, is only fitted to E84 20i, F25 20i, F20 25i, E89 18i & E89 20i, plus any of the F30's & F10/11 that needs low compression ratio (decided by BMW according to specific market requirements, & it isn't a customer selectable option).
If u compare how many high compression U0s they make vs low compression U0s, u can see the high compression U0 is made in far larger numbers than the low compression version. I don't have the numbers off hand but u only need to compare annual sales of the various platforms plus which market those platforms are popular in (e.g. E84 & F25 are mostly sold with diesel engines in EU).
The limited option packages u talked abt is US-specific. For all other markets all the options are a la carte (as long as it's legal), so someone can spec the car as they wish & then apply aftermarket tuning. Remember for a market such as germany the price delta for a 320i & 328i is 4,000 euros.
The Alpina example shows things that are out of spec do & can happen. If actual output is much less than claimed output then it shows there are major problems somewhere along the line, variation or not. Also consider those Alpina engines are specially built by BMW for their exclusive use.



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Originally Posted by bradleyland View Post
1) Why can't they "select engines randomly"? Although I wouldn't call it random. Why not just allocate them as they come off the line? Your hypothesis stands upon two assertions:

a) That manufacturing variances in the N20 are significant enough to justify this binning approach. What I cannot wrap my head around is why the N20 would suffer from these variances, but other BMW engines do not. If all engines do suffer from these variances, then it would be considered "acceptable", and BMW would have no reason to go through the extra effort of waiting for a "defect" engine, subjecting their production process to variances in availability based on defect rate and yields.

b) That "it is only logical for them to detune those not so good ones as a U0". Why is that any more logical than simply applying software as allocation is required?
We do not know the exact power/torque output variances that exist between the engines, as well as the percentage that falls below that range. One thing is certain is that it's very rare to have engines that produce exactly the same power & torque rev for rev, so variance do exist however small it is. This is not exclusive to the N20. We also do not know how tight the standard is used by BMW. It could be that, judging by the dyno plots in this forum on stock O0's, BMW uses an extremely strict set of criterias for their tests. As they dyno every engine made, they can easily identify which engine is a potential candidate to be a U0 if it needed to be. Remember the production numbers for the low compression U0 is much much less than the O0, they can easily select those that give dyno numbers that lie in the lower end of the acceptable range.
As to why it's logical for them to detune the bad ones, that's to protect their bottom line. They don't want a 20i to be tuned to a 28i with no side effects. That's especially true for markets that have very high taxes.

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2) I think I have a pretty good understanding of your hypothesis. I disagree that "If they detune the engines randomly then it will introduce problems." What problems will be introduced?

The binning approach flies in the face of everything I know about manufacturing and supply chain management. I build software to manage the procurement process for Fortune 500 companies. I spend a lot of time with executives in charge of supply chain management, because they're often the ones doing the purchasing. Auto makers rely on just-in-time manufacturing. Cars are built as they are ordered. All the parts arrive in the order they are needed. Literally, every sub-contractor has to load the parts in the containers in the order that they will be needed for assembly. The idea is that a part should be manufactured as late in the process as possible in order to reduce the capital required to maintain parts stock.

An engine is one of the most expensive and complex components in an automobile. If BMW uses binning, it means that the availability of '20i engines is subject to defect rates and yields. That means we're dealing with statistical probabilities. When you flip a coin, there is a 50/50 chance that you'll get heads, but anyone who has flipped a coin knows that you can end up with 6 tails in a row. Or 10. Or 20. It's possible!

The question is not why, but *how* could BMW run an efficient production process if they subject their supply to this type of statistical allocation? If the next engine needed is a '20i, and they end up with six '28i capable engines in a row, what do they do with those engines? Surplus is synonymous with waste when it comes to supply chain management. Engines are too expensive to have them simply sitting around.

This is a matter of applying Occam's Razor. There must be some advantage to the binning approach versus straight forward allocation. I can't see it. I understand the idea. I'm open to considering it, but before I can agree, I need to know the reason why.
Simply speaking their bottom line will be hurt if the engines can be upgraded by a simple & cheap remap. So far nobody has managed to bring a 20i up to 28i levels without major effort.
I understand that JIT manufacturing is a standard implementation nowadays. With BMW engines it's a bit different. The majority of N20s are made in Munich, & they supply exclusively to other plants worldwide. Apart from Munich (& other German plants) it takes at least 1 mth for the engines to reach the respective assembly plants. That's the reason why for a lot of markets it takes many mths from ordering to taking delivery (e.g. production takes place 1-1.5mths after ordering) and also the SA made cars have an extended lead time. In actual fact BMW try their best to dictate demand, hence the existence of dealer & importer sales allocations. With these allocations they have a very good understanding on wht is needed during certain periods of time, as the dealers & importers have a commitment to buy at least the required volume from BMW. The only variable in this case is the equipment spec (not the engine version).
As for randomness, it doesn't matter cos a good one can always be detuned. The surplus good ones won't be sitting idle cos they'll be used to fulfill the lower grade demand. It doesn't cost BMW anything to do things this way as they already dyno every engine.
One thing to note is that the high compression U0s (i.e. those BMW that have complete control in terms of production numbers) are fitted to all BMWs made in German plants, except for the E84. Whereas the low compression (i.e. those binned) ones are fitted to all cars made in Spartanburg (F25 & E89). It's probable that when JIT is needed & achieveable then they won't use the binning approach whereas they'll use this approach when JIT is not achieveable. A related question is why BMW, after spending all these money, do not use the high compression U0 on all the platforms that use that engine, rather than wht they're doing now.

Last edited by clarence; 01-25-2013 at 06:47 PM.
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      01-25-2013, 12:57 PM   #349
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Only 328i and 335i sell largely in North America. Everywhere else in the world the 320i and 320d are the bigger sellers. This is due to the emissions/consumption tax. I highly doubt BMW is binning engines for 320i. I do know that the drive shaft is different from the 320i and the 328i. The 328i's drive shaft is larger and can handle more torque. As for the engine differences I do not know but something is changing the compression ratio.
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      01-25-2013, 02:06 PM   #350
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Originally Posted by clarence View Post
The low compression U0, which has no physical difference to the O0, is only fitted to E84 20i, F25 20i, F20 25i, E89 18i & E89 20i, plus any of the F30's & F10/11 that needs low compression ratio (decided by BMW according to specific market requirements, & it isn't a customer selectable option).

If u compare how many high compression U0s they make vs low compression U0s, u can see the high compression U0 is made in far larger numbers than the low compression version. I don't have the numbers off hand but u only need to compare annual sales of the various platforms plus which market those platforms are popular in (e.g. E84 & F25 are mostly sold with diesel engines in EU).

The limited option packages u talked abt is US-specific. For all other markets all the options are a la carte (as long as it's legal), so someone can spec the car as they wish & then apply aftermarket tuning. Remember for a market such as germany the price delta for a 320i & 328i is 4,000 euros.
That is an interesting note (bolded), but I think it supports my hypothesis better than yours. If the production runs are smaller, then the binning approach makes even less sense. I'm still not convinced that BMW is concerned with broad scale modding affecting their bottom line.

Also, think about the entire argument you're making about BMW trying to protect their bottom line against chip-tuned 320i cars competing with a standard 328i. A chip-tuned 180 HP N20 is capable of 230-ish WHP according to the dyno chart referenced here:

http://www.f30post.com/forums/showpo...2&postcount=14

So customers could still buy a 320i, then chip tune it to get factory 328i power. In this case, BMW has failed in the goal that you set for them.

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Originally Posted by clarence View Post
We do not know the exact power/torque output variances that exist between the engines, as well as the percentage that falls below that range. One thing is certain is that it's very rare to have engines that produce exactly the same power & torque rev for rev, so variance do exist however small it is. This is not exclusive to the N20. We also do not know how tight the standard is used by BMW. It could be that, judging by the dyno plots in this forum on stock O0's, BMW uses an extremely strict set of criterias for their tests. As they dyno every engine made, they can easily identify which engine is a potential candidate to be a U0 if it needed to be. Remember the production numbers for the low compression U0 is much much less than the O0, they can easily select those that give dyno numbers that lie in the lower end of the acceptable range.
As to why it's logical for them to detune the bad ones, that's to protect their bottom line. They don't want a 20i to be tuned to a 28i with no side effects. That's especially true for markets that have very high taxes.
Simply speaking their bottom line will be hurt if the engines can be upgraded by a simple & cheap remap. So far nobody has managed to bring a 20i up to 28i levels without major effort.
Then they've failed for the reasons I've outlined above. I just can't accept this as the rational motivation, as it is not satisfied by the solution.

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Originally Posted by clarence View Post
I know all these JIT manufacturing & stuff. With BMW engines it's a bit different. The majority of N20s are made in Munich, & they supply exclusively to other plants worldwide. Apart from Munich (& other German plants) it takes at least 1 mth for the engines to reach the respective assembly plants. That's the reason why for a lot of markets it takes many mths from ordering to taking delivery (e.g. production takes place 1-1.5mths after ordering) and also the SA made cars have an extended lead time.
As for randomness, it doesn't matter cos a good one can always be detuned. The surplus good ones won't be sitting idle cos they'll be used to fulfill the lower grade demand. It doesn't cost BMW anything to do things this way as they already dyno every engine.
Ok, so sometimes the 180 HP U0 engines are made from defects, but sometimes they're not. Doesn't this also degrade the strategy you've outlined?

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Originally Posted by clarence View Post
One thing to note is that the high compression U0s (i.e. those BMW that have complete control in terms of production numbers) are fitted to all BMWs made in German plants, except for the E84. Whereas the low compression (i.e. those binned) ones are fitted to all cars made in Spartanburg (F25 & E89). It's probable that when JIT is needed & achieveable then they won't use the binning approach whereas they'll use this approach when JIT is not achieveable. A related question is why BMW, after spending all these money, do not use the high compression U0 on all the platforms that use that engine, rather than wht they're doing now.
Interesting, but there's still the matter of motivation. Simply protecting their bottom line still doesn't make sense for the reasons outlined above. What if, instead, they use the low-compression engine in foreign assembly plants expressly for the purposes of JIT. If all your engines were identical, you could just flash them with the appropriate software and send them down the line. I don't have an explanation for the lower than normal tuning results from the 20i, but maybe there is some other unknown factor?
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      01-25-2013, 03:16 PM   #351
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There are 2 versions of the U0 engine (U0 is 20i's state of tune whereas O0 is 28i's state of tune) - high compression version & low compression version. The HC version has comp ratio of 11:1 whereas the LC version has comp ratio of 10:1 (i.e. same as O0). As confirmed by BMW China tech staff, the HC version have different piston crowns. They also confirmed that detonation will occur if the HC engine is ran at O0's (i.e. 28i's) level of boost.
Hence tuners cannot get O0's level of output using this version of U0 with just a piggy-back (AFAIK the DME on the N20 has not been cracked). Major upgrades need to be done to reach around 235ps (confirmed by poster several pages back).

The LC version of the U0 can theoretically be made to output at O0's level of output by running at O0's level of boost (or close to it's rated output if binned due to some "defect"), but it seems no tuner have tried to distinguish between these 2 versions of U0. There can be several reasons for this, e.g. this engine is only fitted to E84 & F25 during certain production dates, & for certain production dates it also had a different turbo, so it may be difficult to find a development car. As BMW themselves don't disclose why each of these LC engines are classified as U0 rather than O0, the tuners had to play safe. Again as the DME has not been cracked so all they can offer is a piggy-back.

The testing u mentioned is already done during prototyping stage, wht they do at the plant is a dyno run. A failure can be caused by sth as simple as the engine missing a few Nm's compared with the rated torque at idling speed.
Thanks for the summary, I was following the thread quite closely, but it's nice to have all the info in one thread.

But let me rephrase my criticism against your binning hypothesis in a clearer form. I am not rejecting the notion that there would be some binning. I am arguing that that alone is not enough to explain why the low output version cannot be made to generate higher output for long enough for someone to develop and sell the software.

In other words, if you apply a cut on a continuous distribution with one maximum, most of the failed cases will come from just below the cut line, meaning that they will be very similar to the ones that barely passed the cut. Now, we know that the ones that pass the cut is very likely capable of withstanding high output for 100K miles or longer. Then there is no way that the ones that barely failed the cut, which is the most likely case, will be so different from the ones that barely passed, that no tuner can tune it up long enough to market a product.
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      01-25-2013, 03:58 PM   #352
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The fuel consumption figures are really disappointing. BMW was able to de-tune the N20 engine (60hp less) and they can't get it to be more fuel efficient?

What the hell happened with the Efficient Dynamics BS they keep shoving down our throats?
A Smaller engine, or detuned engine, and the car still weighs the same.. so its pretty obvious why the gas mileage is a bit lower, it has to work harder to move the car..

and to be honest, I think this car will sell ridiculously and eat into the 328i, as the amount of people I see in NY with base 328s that clearly buy it for the brand, this will become the cheaper alternative..
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