08-17-2014, 10:48 AM | #89 | |
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The whp number of 375ps the MAHA measured, is actually what a 431PS engine with 13% drivetrain losses would get... |
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08-17-2014, 11:00 AM | #90 | |
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Further, where do you get that 13% number from ? To me it does not seem to have any foundation. As I pointed to you many times before, the shape of the P-rad curve does not correlate to anything we have seen. You cannot only consider the peak power numbers to establish losses, at which RPM they are obtained is also important. By your logic, the F8X would have 25% drivetrain loss at 7300rpm since the Maha dyno WHP is about 325ps at that RPM. Think about it a little... Last edited by CanAutM3; 08-19-2014 at 01:25 AM.. |
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08-17-2014, 12:08 PM | #91 | |
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It's all over the place because the M4 was 34PS over the factory claimed number, the AM Vantage V12 was 34PS under the factory claimed number. And other dyno results in their Supertests have also shown a inconsistency/variation from stated factory numbers. The MAHA chp numbers seems to be just as reliable as Dynojets and the other chassis dynos out there... |
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08-17-2014, 01:37 PM | #92 | |
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Last edited by solstice; 08-17-2014 at 01:57 PM.. |
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08-17-2014, 02:31 PM | #93 | |||||
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And the factory stated HP is measured on a multi million engine dyno certified to do that. Seems like many by default and conviction assume those dyno tests are inconsistent. NO chassis dyno is certified to measure crank hp... We can either choose to believe a chassis dyno that is not certified to measure crank hp and which we we have plenty of evidence has a variation of 10-15% between them. Or, we can choose to believe the independently measured hp numbers taken on a engine dyno at a technical service. For me, the choice is really easy Especially when trap speeds/performance also match the factory stated hp number! Even the OP (P1) of this thread admitted that the S55's average power of 425HP "quite possibly" could explain the trap speed of the F8x... Shouldn't that be a hint that there might be questions about the OP's simulations, when he hadn't given any thought to the difference in average power of the S55 vs S65? And him being honest enough to agree that this "quite possibly" could account for the difference? I know you don't put much trust in regulators and the manufacturers ability or willingness to comply , but for information for the rest of us I will just post what Directive 2007/46/EC says about conformity: http://eur-lex.europa.eu/legal-conte...140101&from=EN" rel="" target="_blank">http://<a href="http://eur-lex.europ...01&from=EN</a> Quote:
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I might be naive, but I find it very unlikely that a European manufacturer deliberately and knowingly deceives and misleads EU type approval authorities. There is a regime to verify conformity, including spot checks at random. So the risk of being caught cheating definitely is present! And with all the forum activity about under rating, the good people responsible for those spot checks might find it relevant to do a spot check on engine power... (Lot's of those working in the auto industry, on both sides of the "fence", are car enthusiasts reading forums like these (posting as well perhaps )...). That is something BMW obviously will need to have considered as a possibility if they have indeed under rated their engines to the extent it's claimed here. And, no I also don't believe that there is a mysterious factor inside, or outside, the dyno room explaining a "legal" difference of 60-70hp. It would also be strange that that factor only should be present on the S55... If anything, the dyno room is a ideal environment and should not yield lower power ratings. Let me also add that this isn't proof of no underrating, merely evidence based on a regime of testing, compliance and spot checks to verify that compliance. And, another (unrelated to this thread) interesting legal requirement: Quote:
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08-17-2014, 05:37 PM | #94 |
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Looking at some MAHA dynos for some other BMW FI engines they don't seem to vary wildly vs rated hp instead they are pretty much within the regulation allowance:
N63: 393.7 vs 400 hp rated. http://www.benz**********/content.ph...d&snpAttempt=1 S63TU: 573.7 vs 560 hp rated http://www.aston**********/content.p...2&snpAttempt=1 N55: 307.1 vs 300 hp rated http://www.***********.com/content.p...atted-downpipe The S55 seem to be the exception by generating far more power vs stated on the MAHA than other BMW FI engines at 465 vs 431 stated. Edit: seems like copy of the links doesn't work. Just google the engine and maha dyno and check the results. And is an underperforming British car really a surprise Furthermore the AM's engine is hand-built. Precise conformity must be even more tricky between species. Last edited by solstice; 08-17-2014 at 06:04 PM.. |
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08-17-2014, 09:46 PM | #95 | ||||||||||||
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Correction: The 13% power changes you're talking about on the S65 may be more understandable the more you study their sources. I know you've been around long enough to see this analysis before. 91 Octane vs. 93 Octane and 6MT vs. DCT both account for some of those differences. Then sometime around late 2010 or early 2011, a software update was introduced that bumped base power significantly. By memory, I think it was about 10 whp bump. I've seen multiple independent vendors report the same increase in power at about the same time. Quote:
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Correction: Yes we've read the SAE documents. Without this knowledge, we wouldn't have been able to comment about the lacking humidity input in the Insoric section of our article. BTW, you forgot to mention the SAE correction also accounts for mechanical efficiency. Quote:
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One thing about the Dynojet models in CarTest. We can't speak for other dyno brands and we don't make any claims about them. All we're trying to say is that we have a track record of simulations that match real world data, and that track record is based on using Dynojet SAE corrected results. If it's not broken, don't fix it. 1. Chassis dynos, explained, we use Dynojet for CarTest simulations. 2. In-situ, wheel based, Insoric dyno, flawed, 3. Maha whp results, completely misunderstood 4. Trap speeds (and other performance metrics), consistent with simulations 5. BMW stated crank hp, BFD 6. Simulation, matches real-world results 7. Legal requirements, very interesting. SAE isn't a legal requirement, it's a standards body. Makes me wonder if EEC is the same thing. Now that I've read 3 or 4 of those documents, they don't appear to have any teeth in them whatsoever. Like the SAE, they sound like a standards body that if you want to put their stamp on something, you need to comply with their procedures. The later documents posted in this thread all but say it's voluntary. There are ample quotes by Boss330 from the EEC documents themselves that indicate that submission is purely voluntary; but once you submit, you are bound to the agreement. Again, sounds like it has absolutely no teeth in it whatsoever. But I'm also going to hedge my bets by saying I'm not an expert in anything regarding the EU. |
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08-18-2014, 12:11 AM | #96 | ||||
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You can of course say that it's voluntary to sell cars in the EU market... But as a mass manufacturer (or even low volume, but with less rigid regs) you HAVE to get a EU type approval to be allowed to sell your vehicles throughout the EU market. I know, I work with this every day of the week... Article 4, #3 of Directive 2007/46/EC (the framework Directive), clearly states that this isn't voluntary. The notion that it hasn't got any "teeth in them whatsoever" is clearly wrong: Quote:
The EU type approval information document for the M3/4 lists that engine power is in accordance with: Quote:
US legislation differs from EU in that it relies on self certification from the manufacturer. From Wikipedia: Quote:
Please also explain what we all got wrong in our understanding of the MAHA whp (this genuinely is something I'd like to know more about, and since you claimed we have gotten it wrong I also assume you know the correct answer here). The INSORIC at least seems to get very consistent and good results, flawed as you might claim it is... Engine power within the EU allowed tolerances. Last edited by Boss330; 08-18-2014 at 06:05 AM.. |
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08-18-2014, 04:58 AM | #97 | |
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As regards hand built engines. Please think over what you said one more time... In engine building there is something called "blueprinting". That is when a engine is hand built to be as close as possible to the specs and tolerances in the blueprints of the engine's design. Hand built engines are hand built in order to be more close to spec and has tighter tolerances. Bespoke racing engines are hand built, both because of cost of tooling but because with mass production there is always bound to be variations in the different components. Meaning that there needs to be larger tolerances in order for all the components to fit together (like if you have a crank journal diameter that is on the large end of the manufacturing tolerance and a bearing liner in the block on the small side of tolerances). In a hand built engine, dimensions are usually hand measured and the proper thickness bearing is chosen so that the tolerance is much closer to the optimal designed tolerance. |
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08-18-2014, 10:34 AM | #98 | |
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08-18-2014, 10:47 AM | #99 | |
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08-18-2014, 10:54 AM | #100 |
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Well there's the factor of use and abuse as well prior to getting each car on a dyno. I also think there are a fair amount of human touches on each complete car. Then there is material and environmental differences during production. But between hand built and robot built entities I would say the chance of conformity is stacked in favour of the robots with a large amount. Last but not least are SW updates and configuration tuning of ECU,DME and robots.
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08-18-2014, 11:32 AM | #101 | ||||||
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Is there such a thing as a member state which doesn't grant EC type approval? What happens when a vehicle fails to gain certification because it doesn't pass section 8.1 during testing? Does that mean that car can't be sold in the EU? I still have my doubts. Quote:
Once again, I'm going to mention the irony of others arguing against SAE/EEC weather correction formulas while at the same time arguing for the inviolate law of EEC regulations whose enforcement depends on the accuracy of these same weather correction formulas. Quote:
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08-18-2014, 02:19 PM | #102 | ||
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Many member states don't issue type approvals. Germany, Italy, France, England are the main countries issuing type approvals. That's because that's where manufacturers mostly are placed and where there are technical services (test laboratories) placed to do this. If a car model has received type approval, that means it can be sold and registered in any EU country (just like a US car that has the "This vehicle conforms with all applicable FMVSS standards in place at the date of manufacture" can be sold in every US state. A car can't have more than one EU type approval. If it has a type approval number starting with e1, that means it was issued in Germany. I see you have your doubts as regards type approval in EU. But, yes I can assure you that a mass produced passenger vehicle in category M1 (a car with a maximum of 9 seats in total) that fails to meet the requirements of the technical directives, can not be registered in member states. There are certain allowances for small volume type approval, one off vehicles and amateur built vehicles. A one off vehicle in category M1 can instead undergo a IVA procedure (Individual Vehicle Approval), but this means that EACH individual car has to be documented according to each of the technical Directives in Annex IV of 2007/46/EC. And that includes engine power as well... I will once again quote what Directive 2007/46/EC says about the need to comply with the required standards: Quote:
As I said previously, type approvals and EU legislation is something I work with on a daily basis. Getting the M3/4 type approved for sale in EU isn't something BMW can opt out of! As regards the engine power testing, I'm not sure where the confusion is? The manufacturer has to submit a engine for testing. This has to be measured according to the standards and the entire power curve has to be verified. If the max power is within 2% of the stated hp and if the remaining test points are within 4% of what the manufacturer states, then the engine's factory claimed power can be accepted. This is 8.1 and concerns the engine submitted for testing. That has to be within 2% of factory claimed max hp. And then we have 8.2 which concerns conformity of production. This means that when the authority, or technical service, does spot checks during production (which could be today, next month or in two years), the engine they pick for conformity of production (a random engine) has to be within 5% of the approval figure. For type approval testing, the requirement is a tolerance of max 2% on max power. For the subsequent testing for conformity of production the tolerance is higher at 5%. Which is why we repeatedly have said that if the S55 indeed is under rated, then that most likely won't be more than by the EU tolerance of 5%. Since this both IS a legal requirement that BMW needs to adhere to, AND a requirement BMW has adhered to in acquiring EU type approvals for the M3/4, this should lead to the following conclusions: 1. BMW presented a engine (with DME, intake and exhaust systems as per production spec) for type approval testing that was within 2% of the claimed HP 2. The engine submitted for testing was either: -Completely in conformity with requirements and with the engines subsequently used in production vehicles -Not in conformity with the engines later used in production vehicles If BMW have chosen the latter solution, then they are playing a dangerous game as they risk getting caught cheating as soon as conformity of production spot checks take place... To me this seems unlikely and such a policy would result in hugely bad PR for BMW in EU if they are caught cheating (heads would roll at BMW M HQ)! And I would say that any claim of under rating in the magnitude that is claimed (60-70hp) certainly also HAS to imply wrongdoing by BMW with regards to type approval testing. Unless we are to believe that the engine dyno test is so flawed that it misses the engine's performance in the car by 60-70hp (or 14-16% in this case)... I don't believe that there is anything "magical" happening when the engine is mounted in the car that suddenly increases power by 60-70hp over what it had on the engine dyno! That means that any claim of under rating also needs to consider the likelyhood of BMW knowingly deceiving the governing bodies of all EU countries these cars are marketed in. Yes, that might be the case. Maybe BMW couldn't care less about possible consequences and loosing type approval for the F8x (and thereby be unable to sell the cars in the EU). And, it doesn't matter who made the comments about MAHA whp. You said that this was "completely misunderstood". I would REALLY like to have your explanation on what was completely misunderstood and what the correct understanding is. The MAHA dyno is something we genuinely have debated here and are curious to learn more about! Since you claimed that we had completely misunderstood the whp from a MAHA, I'm sure you can explain where we went wrong (at least in the two posts you read)! Last edited by Boss330; 08-19-2014 at 05:16 AM.. |
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08-18-2014, 05:18 PM | #103 | ||
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By hand built we don't talk about a person making the components from scratch. The components are manufactured by CNC operated machines. But with any such machining there are variations in manufacturing. As tools are worn, there becomes differences (small but present) as well as numerous other factors. On a "robot" assembled engine all engines are put together using the same std components. Meaning that there needs to be a certain amount of tolerances present in order to allow for components on the low or high end of tolerances. On a hand built engine, all the components aren't only assembled by hand, but measured individually and the assembler makes sure all the tolerances are within a much smaller margin than mass production can allow for. The difference is becoming smaller, but a hand built (assembled) engine is hand assembled in order to have lower tolerances and being closer to the optimal tolerances for each component. I've been to several engine builders, including F1 engine supplier Cosworth and witnessed this meticulous process of hand built engine. BTW, a little known fact is that Cosworth hand assembled some of the special versions of the AM V12 engine (I was there when some of that took place). The regular V12's are assembled by Mahle in Germany... Oh, and the AM V12 is basically two Ford V6 engines put together... Developed when AM was owned by Ford and based on the then current Ford 2.5 and 3l 60deg V6 engines. |
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08-18-2014, 05:34 PM | #104 |
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You don't build several thousand F1 engines. Further more these engines do not need to be exactly the same, they just need to be good and follow the F1 framework. You don't hand build when you manufacture large series and replication is not a main goal of hand building. Another reason for hand building is cost of setting up a fully automated production. It make sense to hand build at low volumes of exotic units that can carry high cost. Automation is likely preferable of many reasons, consistency is one of them but if you build few engines the investment might not make sense.
If you think hand built engines of a larger volume is more identical to each other than robot production, think again. Last edited by solstice; 08-18-2014 at 05:41 PM.. |
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08-19-2014, 01:38 AM | #105 | |
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Properly "hand built" engines usually include more steps during the assembly process to ensure optimal fits and gaps, which allows for tighter tolerances. They will be less identical because each engine is sort of customized which yields a more optimized engine. |
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08-19-2014, 02:09 AM | #106 | |
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08-19-2014, 03:48 AM | #107 | |
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I will also add that a F1 engine doesn't merely need to be good, they need to be assembled to a much higher level of precision than a production car engine. In 2006, the Cosworth V8 raced at 20.000rpm. And before there was a limitation on how many F1 engines you could use each year, the teams brough around 10 engines per weekend. Those engines where dismantled and reassembled after each GP weekend. That means that back then each team went through as many as 100-140 engines each (not always a brand new engine, but one that was disassembled and reassembled for every race weekend). There was 10-12 teams, which means that roughly 1000-1500 engines were built each year (by 3-6 engine suppliers). But, F1 engines aren't the best example of higher volume hand built engines. They are however a prime example of hand assembly in order to make sure that each engine is as optimally put together as possible. That means you just can't grab a set of bearings and throw in as a replacement. You need to measure and find the optimally sized bearing for the combination of tolerances on the parts you assemble (as well as with the other components of the engine). It's kind of like a VERY high end watch. Hand assembly in order to make the most presice and accurate clockwork possible. An article explaining the principles of engine blueprinting: http://www.precisionenginetech.com/t...inting-part-1/ And here is a example of modern, high volume, hand assembly of engines with the AMG concept of "one man, one engine": http://www.mercedes-benz.ca/content/...mg/engine.html https://www.mercedes-amg.com//video/...erview_eng.mp4 https://www.mercedes-amg.com/engineering.php?lang=eng Here is a typical mass production robotic assembly line. Would you rather have your engine assmbled by the workers in this video or in the AMG video |
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08-19-2014, 06:20 AM | #108 |
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Very smart post P1 and without the BS
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08-19-2014, 09:42 AM | #109 | |||
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http://www.unece.org/fileadmin/DAM/t...regs/r085e.pdf This is how evaluation of results under conformity of production testing is described here: Quote:
http://www.unece.org/fileadmin/DAM/t...gs/r085a5e.pdf Pretty detailed info on the engine to be tested... And, in the EU regulation (136/2014) that now refers engine power to be according to ECE Reg 85 there is also a provision for engines like the S55: http://eur-lex.europa.eu/legal-conte...4R0136&from=EN Quote:
This is also now acknowledged in legislation on engine power and correction factors. So the regulators don't necessarily use correction factors anymore. Taking one more inaccuracy out of the equation... Last edited by Boss330; 08-19-2014 at 10:09 AM.. |
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08-19-2014, 11:16 AM | #110 | |
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Tolerances is totally unrelated to variances between engines. You can have two totally different engines with 1000hp difference and they can have the same tolerances. This is impossible with two new near identical robot built engines independent on what tolerance they are built at. That hand-built engines can be built to higher tolerances does in no way mean that they are built to higher conformity as a series since they aren't. Robots are simply superior in repeating the same procedure with the same parameters time after time than any human. I can very easily see how one hand-built Vantage V12 engine can be built with 34 hp difference to another ( while still being built to equal tolerances ). It's a bit harder to see with robot built S55s. If it happens it's more likely due to the parameters I mention in another response than production line variations. It's becoming slightly OT but my main point is that the AM is not the best evidence to discredit the precision of the MAHA dyno's crank hp calculation. I would think the precision against other BMW FI engines like the S63TU, N63 and N55 are better indicators when evaluating the S55's result. If you don't agree let's leave it at that to not make this slight sidetrack dominate this thread and risk overshadow all good work done by the OP. Last edited by solstice; 08-19-2014 at 12:06 PM.. |
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