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BMW 3-Series (E90 E92) Forum
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JB4 CPS offset dyno testing and logs
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03-22-2011, 10:09 PM | #45 |
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well this is a more indept subject then just adding timing with rpm due to piston duration time decreasing. On some N/A platforms advance will remain constant from mid to top because min timing for max torque does not increase. this is because of cylinder turbulence, heat, and maybe piston compression speed increase burn rate. the chamber design, quench, squish, cam profile, etc plays into this formula. In FI engines detonation is more of an issue than MBT I believe. and of course port and direct injection will have an effect. anyway, i'm sure others can elaborate here.
Probably decreased detonation time and load are the main factors for us in the top. |
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03-22-2011, 10:26 PM | #46 |
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KISS.....
still think running 14.5 psi on 91 octane is too much boost for the octane. I can get a knock free curve in 3rd gear on 13.5 psi with 94 octane using -3 degrees of offset down low and tapering up to -1.8 degrees as I approach redline. That's with 94 octane. If I add just 1 more psi of boost, I can induce a timing dip. I think there are plenty of procede logs posted on here that show good timing curves with much less offset than BMS is using. Makes me think their approach is flawed and their conclusions follow that. |
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03-22-2011, 10:43 PM | #47 |
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I am sorry for not being constructive on the topic of this thread...
From everything that I've read on multiple threads on three different forums over the course of close to 16 months, it seems to me that BurgerTuning is simply making up some weird lame black box they call a piggy back tune, then they "throw that shit to the wall and see if it sticks". Clap, JPSlick, Sniz, and the rest of you guys: I really appreciate your knowledge and technical skills, but for the love of God, stop educating BMS. Let them figure how engine tuning works on their own... If motors start blowing up, more end users will realize something is not kosher and they will either demand improvement from BMS or they will jump ships like rats from a burning boat. Either way, this will (hopefully) force BMS to produce a better product. </rant>
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03-23-2011, 07:14 AM | #48 | |
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Mike |
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03-23-2011, 07:19 AM | #49 |
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Sorry went out and bought another rc car last night. Tonight I will show you why your data on map 2 is useless. And actually the offsetted map 1 looks smoother. Simply match up the timing drops with the dyno....maybe you wi get a.clue.
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03-23-2011, 08:14 AM | #50 | |
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This is why mustang dynos, dynopacks, etc are so popular. You can set the roller speed and go through every load cell at every rpm in the tables to set the proper timing curve while monitoring torque output, egts, and afr so that you get everything set up to induce efficiency, safety, and reliable power deliver that is CONSISTANT in many conditions (leaving that buffer for when conditions deteriorate). Just some free info for you. Just offsetting a bunch of degrees isn't how you are going to test the tuning facts we presented in those long drawn out threads in the past. Actually offsetting timing properly for each load range (I guess rpm-vs-map in the tables for the piggy backs) would be a bit more logical and relevant. This has nothing to do with which tune I run or blah blah blah - this is just tuning 101 MAYBE 102? If I drop a ton of timing or advance timing (too much) down low I am setting myself up for failure by creating cylinder atmospheres that are more readily susceptible to knock. Tuners get paid because they are able to find that "just right" spot where its not too much or too little. In regard to my bolded section of your post - the data doesn't show anything of the sort. It shows that just offsetting by different values isn't working. If you go back and actually apply tuning logic / knowledge to the offsets and do so appropriately throughout the rpms you will see the results you know will show up or maybe you really don't know...either way the results will support what physics and tuning facts dictate. Maybe this isn't possible - I am guessing Terry created tables that have cells that represent sections of a map where as you can pinpoint 4800rpms and 14.5psi of boost - if he doesnt have actual tables in which he can enter desired + or - offsets to the factory timing curve I can see why this is more difficult and unsuccessful thus far. Last edited by Jake@MOTIV; 03-23-2011 at 08:29 AM.. |
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03-23-2011, 10:03 AM | #52 | |
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Thanks for confirming what I am saying........ 14.5 psi on 91 octane is a recipe for knock. I think that to stay relatively knock free, you have to be in the zone of correct boost with correct timing offset which maxes out the timing curve to just below the knock point and of course, appropriate octane for your boost. That's where the tuning skill comes into play. That is probably why the 13 psi curves look better on 91 octane than the 14.5 psi ones do. You just can't keep feeding more and more boost on crappy octane without changing anything else and still expect to make knock-free power. Offsetting timing on 91 octane does not appear to be enough to compensate for the higher combustion temperatures at 14.5 psi. It's not an insult.....it's just physics. Last edited by Ilma; 03-23-2011 at 12:26 PM.. |
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03-23-2011, 10:26 AM | #53 | |
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03-23-2011, 11:42 AM | #55 | |
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Have you no decency? |
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03-23-2011, 11:48 AM | #56 | ||
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Be that as it may... Mike- tuning 101. Torque is your enemy and your friend. This car makes its largest torque in the mid-range. That is going be a "hot" area. You would by no accident find your least amount of ignition in those areas. Tuning 102- If you reduce timing before your timing drop outs it will never reach the knock threshold to induce a timing drop out. Instead of reinventing the wheel of tuning, think about how all other flash tunes operate, even better, look at that stock ignition and see how its represented. I will give you a hint again, low ignition in the mid-range, ramping up by redline. ITs not rocket science here. All the information is available. Flylow really hit the nail on the head on the explanation. I tried to dumb it down. IDK if you are reading past the word "Timing".... Just like when you swing a bat in baseball, you can either be too late, too early, too high, or too low.... Timing is science and an art. Ive said it before. There is a happy medium. Throwing out offsets for sh*ts and giggles is not ideal. Quote:
Letting someone walk into a burning building just isnt me. Last edited by Jeff@TopGearSolutions; 03-23-2011 at 11:55 AM.. |
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03-23-2011, 12:19 PM | #57 |
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This is quite valiant of you sir! You sure do have a lot more patience than I do...
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03-23-2011, 12:34 PM | #58 |
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While I largely echo the opinions of many of the members here (JPSlick, Clap135, FlyLow335i ect), I've chosen to stay out of this thread for the most part, as it seems like the same points keep being made over and over. The same discussions are repetitive with no resolution.
However, I must say that I applaud Terry for at least making steps that I would have made if I were in his shoes: at least attempting to give his customers the option to modify timing and user adjustability. To anyone who gives a shit about tuning their own car, I think this is a step in the right direction, even if it is an unpopular stance. I'm sure the vast majority of BMS customers will simply stick with the OTS maps provided at purchase and never use these features, but to those seeking optimal tunes (assuming they don't purchase other tuning devices/services), this is a step in the right direction in my opinion. With that said, I have a strong feeling many of these threads will soon be less frequent. I've been no quiet advocate about my intentions (purchase AP & tune my car myself via ATR), and they will soon come to fruition. At this point, the AP will soon be released for the '07's (yay me!!) as they appear to be final testing them as we speak. Last I checked, after that on Cobb's priority list is developing stage 2 maps, then Protuner software followed by ATR software, projected to be completed by the end of Q1 2011. It's almost here. As such, there's really not much of a need to debate topics like this anymore IMO... this isn't meant to be a tuner war/bash, but honestly, soon many of us who have had some experience tuning in the past will have the ability to tune our cars ourselves, and as such, will have the ability to let the results speak for themselves (no need for debate when the proof is in the pudding ). No altering CPS signals, or playing with algorithms that arguably might have negative consequences (another debatable topic I'm going to leave alone haha), but changing the base DME timing maps themselves based on individual need/conditions. Maybe many of us who have tuned multiple platforms/cars in the past will be unable to quantify our suppositions on this platform.... I highly doubt that's the case Although I for one tire from arguing my positions on subjects like this, and intend to simply prove my theories based on previous experience in the very near future. I can only say that I hope many of you feel the same and will be posting your personal findings in the near future with the release of ATR software Either way, I'm sure it's going to be an interesting learning experience on a new platform, and I'm sure the community as a whole will benefit. Happy tuning gentlemen. -Brandon [/OT_rant]
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03-23-2011, 12:42 PM | #59 | |
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03-23-2011, 12:59 PM | #60 |
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I on the other hand went with meth as one of my first mods lol. No need for cps at all if you figure out the boost level at which your car is happy on the stock timing curve given your meth ratio. Cps is not the correct way to run higher boost on pump but it sure is better then having the dme knock.
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03-23-2011, 01:09 PM | #61 | |
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I also agree with roninsoldier83 to a point but also believe as more do custom tuning the number of these threads will quadrupole. Tuning piggybacks is relatively simple given they use absolute boost targets, the PID systems are well developed for these higher boost levels, etc. Trying to do this type of tuning with a flash and keeping it consistent from day to day is not going to be fun at all but I guess that is the challenge. Mike |
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03-23-2011, 01:11 PM | #62 | |
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Even though many people have hung out in that building, hell even lived in the building for years with no issues what so ever. |
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03-23-2011, 01:19 PM | #63 |
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I've got 50k+ miles w/ no cps and the engine is running fine. I can't get into the details with anyone, but do know historics. Based on my experiences and several others, whether or not you stumbled onto something without knowing, a lack of CPS is CLEARLY not hurting anything here at the boost levels I currently run.
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03-23-2011, 01:37 PM | #64 | |
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With all the logs posted by Cobb/GIAC/Procede and JB guys we have around here, does anybody think that 14psi on 91oct, even with full bolt-ons...is a good idea without meth/race gas? Me thinks 91oct and 14psi is already on the "raggity" edge (see urban dictionary). As we have seen, 14psi on 91oct is pushing it on the stocker turbos. And now that it is starting to heat up outside Spring/Summer...wow...knock knock knock. Then, apply poor FI tuning methods with this middle school FI tuning science project Terry is trying to execute = recipe for crap performance and results. Party On!
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03-23-2011, 01:39 PM | #65 | ||
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As long as other people learn from it thats fine with me. Quote:
Notice I didnt put a question mark. Keep your judgments and opinions to yourself, lets stick with hard facts and data. Bringing up some mud to sling through a comment like this does nothing but derail the thread. This is about improving a product.... Dont get it twisted. I'm starting to lose patience with the people above..... and the same fanobis just coming in with their .02 and no tuning background. I'm all for questions, but the derail JB camp is simply annoying. Last edited by Jeff@TopGearSolutions; 03-23-2011 at 01:45 PM.. |
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03-23-2011, 01:55 PM | #66 | |
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At least Terry is on the right track but its a bit painful seeing the learning curve that others knew before the n54 was even an idea in a BMW engineer's head.
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