03-13-2014, 05:22 AM | #45 | ||
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03-13-2014, 09:49 AM | #47 | |
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03-13-2014, 10:12 AM | #48 | |
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Agree that a dyno run without before and after runs doesn't really tell you anything about delta gains. But is seems strange that a DynaPack only shows a wheel torque number that never goes above 500lb.ft between 3600rpm to 6000rpm, in fact dropping to just above 450 at 5000rpm. Especially if the boost is increased by 4Psi. Previously it has been said that the +3Psi setting is only supposed to be used with race fuel. Here we are discussing a dyno run done on 94 octane fuel and the BMS set to +3Psi. I am confused as to what is being said here... On one side it has been said that +3 should only be used with race fuel (100 octane). That leads me to believe that running on lower octane will cause detonation/knock and/or other ignition related issues with the +3 setting. On the other hand it seems that his results/dyno graph is "defended" as being normal as regards the torque curve... So, is it safe to run the +3 setting and that his results are representative of running the BMS at +3? If so, then the stock torque numbers on that Dyna Pack must have been way lower than on the Dynojet graph you posted (since his +3 numbers are consistently lower than the stock Dynojet numbers). |
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03-13-2014, 10:21 AM | #49 | ||
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03-13-2014, 10:33 AM | #50 | |
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I'd love to see a log of the dyno run in question showing boost and timing. Based on that I could offer tuning advice to the owner and help him determine if there is any issue with the car. I do not posess magically powers though. In the absence of any data I can only guess based on the single dyno chart that this run was done in 5th gear (thus the fuel cutoff), that it is a DCT based on the torque dip, and that the runs were done in 5th gear. I can not deduce from the dyno chart what his settings were, what his fuels octane rating was, whether the dyno operator ran the car properly (many don't floor it at low RPM to avoid the kick down), etc. Mike |
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03-13-2014, 10:34 AM | #51 | |
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I'm sure BMS could change that with and post a software update but I shutter to think at the mass confusion it might cause at this point. Some would enter say 4.0 on the old software thinking they have the new software, others would enter 2.25 on the new software thinking they had the old, etc. Mike |
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03-13-2014, 10:38 AM | #52 | |
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If the curve showed top end power rolling off with high frequency jagged edges that resemble stairs going down then I'd say that data points to the conclusion that the DME was pulling timing due to a combination of too much boost and/or not enough octane. IMHO I think this community needs to take it up a notch or two on the analysis level which is why I'm bothering to continue replying here. It's an exhausting job though. Mike PS. Note the stock DCT 5th gear dyno I posted. Why do you think torque is lower at 4500rpm than it is at 3000rpm and 5000rpm? |
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03-13-2014, 10:47 AM | #53 | |
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He has stated that he ran:
No need for "magical" powers! Reading his info would suffice... The dyno graph starts off at 590lb.ft at 2500rpm and drops from that point... Are you saying that the dyno operator only did part throttle at 2500rpm and still managed 590lb.ft |
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03-13-2014, 10:51 AM | #54 | |
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And surely, in 2014 it should be possible to program safety measures into a device, that doesn't allow more boost gain than the engine can take? To me it seems that rushing a N63 developed product onto the S63 has caused some confusion anyway... |
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03-13-2014, 11:21 AM | #55 | |
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The Stage1 is a simpler system. It's functionally identical to every other M5 piggyback I've seen thus far including ones that cost $2500 or more. BMS is the only one of those to offer user logging and user adjustment. The problem is I think people like to make adjustments to things they should not be adjusting. Having gone through this thread though I will lobby with BMS to adjust the firmware such that 3.0 equals 3.0psi. It may be more confusing short term for those running the current firmware but in the long run it will be easier for new customers. On the user adjustment page it lists the firmware date so those making adjustments will need to note the date before entering a value if they choose to do some custom tuning. Mike |
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03-13-2014, 11:24 AM | #56 | ||
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03-13-2014, 11:27 AM | #57 | ||
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I think the suspicion was that by running to much boost, the DME detects a strange situation, possibly detonation/knock, and then decides to reduce boost. That's the reason why there is less torque and a really strange torque curve. As stated previously, it starts at 590lbs.ft at 2500rpm, drops to 500lbs.ft by 3800rpm and stays there until 4400rpm. After 4400rpm it falls down to 450lbs.ft at 500rpm before it climbs back to 500lbs.ft at 5800rpm to 6400rpm. It doesn't resemble the curve you posted very much! Quote:
With the way that curve looks I suspect there is a high degree of smoothing, quite possibly masking any high frequency jagged edges. Ok... |
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03-13-2014, 11:35 AM | #58 | |
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For a doctor I'm surprised you make such bold and absolute statements with such little evidence and understanding of the systems involved! Mike |
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03-13-2014, 11:37 AM | #59 | |
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Interestingly, the ACS piggyback for the M5 is not a CAN piggyback. But is on other models... |
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03-13-2014, 11:46 AM | #60 | |
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I find that hard to believe. Boost is under total control/management of the DME. Surely if it detects a situation where maximum timing adjustment and/or maximum fuelling adjustment doesn't remedy the situation it could reduce boost at any time. The "mechanism" is certainly in place via the DME boost management software. What you are saying is that the engineers at BMW hasn't programmed the DME to be able to reduce boost as a function of knock or fuelling? I'd very much like to have further info on that and the logic behind it For ages the knock detection strategies employed by auto manufacturers have relied on boost management/reduction as one of the key instruments to avoid knock... (Started with SAAB http://books.google.com/books?id=q0qVc8dQrpgC&pg=PA85 ) Seems strange that BMW doesn't want to have control over one of the main contributing factors of detonation/knock??? Last edited by Boss330; 03-13-2014 at 12:11 PM.. |
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03-13-2014, 11:50 AM | #61 | |
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[QUOTE=Mike@N54Tuning.com]
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For a doctor I'm surprised you make such bold and absolute statements with such little evidence and understanding of the systems involved! Mike Seriously you think nothing was wrong with that curve . I think it was mostly pulling timing , but surely the ECU has full control of boost as well . I'm making an educated deduction , that torque curve looks nothing like a stock car nor a car on the correct BMS settings . The only thing the op changed was the settings so ...... |
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03-13-2014, 12:06 PM | #62 | |
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And how can torque be largely independent of timing changes? If you just change the timing slightly (a few degrees) within the optimal range, then you will only see small variations. But if you take a lot of timing out of the engine, power and torque surely will drop... http://www.daytona-sensors.com/tech_tuning.html An article on ignition timing: http://www.autospeed.com/cms/article.html?&A=109132 Last edited by Boss330; 03-13-2014 at 12:25 PM.. |
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03-13-2014, 01:00 PM | #63 | |
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And coincidentally it seems that the issues Renault have had with the 2014 F1 engines have been related to detonation/knock and boost strategy as well...
http://www.autosport.com/news/report.php/id/112888 Quote:
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03-13-2014, 01:12 PM | #64 | ||
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03-13-2014, 01:34 PM | #65 | |
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Don't remember having had arguments with you... I'm not saying that I know what caused his strange dyno reading, but not everything adds up and some claims just seem to contradict engineering basics on engine management, ignition timing influence on torque, knock only happening at high RPMs and the DME not being able to reduce boost as a function of knock or fuelling. But, I'm keeping a open mind and look forward to more in detail explanations on what was meant. |
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03-13-2014, 03:25 PM | #66 |
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Im really suprised by some of the comments people are posting here, much of which are about very vauge dyno graphs that have little to no real information on them regarding what actually is happening during the run, the conditions, logs from the car etc... let alone the cooling systems used during the dyno pulls.
Many of the 'facts' about how a DME actually works that people are posting also seem to have been pulled straight from the first link that came up on google when they went searching for information to help them put together a reply. P.s Im an experienced ECU software tech with many years of experience and I spend 6 days a week developing software on a dyno, mainly for BMW and VAG cars. |
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