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  1. #26
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I think you are confusing VANOS and Valvetronic.
    Lol your right I meant valvetronic but was thinking VANOS.

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    I'd love to see all of these same tests done on higher boost and see if the cps would make more of a difference at a lower percentage.

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    Click here to enlarge Originally Posted by leo985i Click here to enlarge
    Terry. Would you say I'm safe running map 2 with FBO and quality 91 oct? I hate cali gas............
    If you look at my runs, on 91 map 2 isn't making that much power over map 1. I'd probably run map 1 daily and save map 2 for special occasions.

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    You are right. Thanks! I will follow your advice.

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    So with JB4 is the timing always trying to advance? I thought with more load (boost) you have to retard timing? Obviously the timing drops when the turbos start spooling, but it seems that while you are under load it is trying to advance timing. Is this due to a higher RPM?
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  6. #31
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    The DME is always trying to advance timing as high as possible, listening for early knock, and backing off. Then offsetting some of that in to long term trims. That is the basic strategy and it continues with CPS in place. The difference is now we can introduce a lower than normal maximum ceiling. But even with 4-5 degrees of offset there was minimal reduction in timing drops or knock sensor activity. So you'd need to offset more than that to make a real difference.

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    The DME is always trying to advance timing as high as possible, listening for early knock, and backing off. Then offsetting some of that in to long term trims. That is the basic strategy and it continues with CPS in place. The difference is now we can introduce a lower than normal maximum ceiling. But even with 4-5 degrees of offset there was minimal reduction in timing drops or knock sensor activity. So you'd need to offset more than that to make a real difference.
    Okay thanks, I am just trying to better understand what is going on. I am definitely going to keep the JB4 how it is though. Sorry if this is a stupid question, but could you explain why its always trying to advance timing? I thought the goal was to have peak combustion at 15 degrees ATDC.

    Thanks!
    Click here to enlarge


  8. #33
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    Click here to enlarge Originally Posted by Gbreee90 Click here to enlarge
    Sorry if this is a stupid question, but could you explain why its always trying to advance timing?
    Peak performance/power.
    Stage 2 or 2.5 E9X M3 S65 V8 supercharger kit for sale: http://www.boostaddict.com/showthrea...r-kit-for-sale

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    Click here to enlarge Originally Posted by Gbreee90 Click here to enlarge
    So with JB4 is the timing always trying to advance? I thought with more load (boost) you have to retard timing? Obviously the timing drops when the turbos start spooling, but it seems that while you are under load it is trying to advance timing. Is this due to a higher RPM?
    You are correct that with more boost timing should be retarded. Problem is that because these piggies don't allow the dme to know that boost is increasing past stock max boost it leaves timing advanced to whatever the ignition map is set for at stock full boost and when this creates knock the dme pulls back. I haven't understood yet how it would "learn" to prevent this long term as it doesn't know what boost it's running when the knock occurs. The adjustment it has to make at 13psi is probably substantially bigger than at 15psi but I may be wrong here. If it truly learns how to run the higher boost then after a few miles or pulls on a dyno at a given boost we would no longer see any knock sensor activity in subsequent runs. That may very well be the case I just haven't seen it.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Peak performance/power.
    But if you advance timing too far the flame front will try to push the piston backwards during the compression stroke. I am guessing after a second of that happening knock would occur due to increased heat and then the JB4 would retard timing. Is this correct? If so, does anyone know what this point is? Maybe the DME isnt even capable of advancing that far. I would think BMW engineers would take that into account and prevent it from happening.
    Last edited by Forcefed; 03-22-2011 at 07:16 PM.
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    Click here to enlarge Originally Posted by Gbreee90 Click here to enlarge
    Okay thanks, I am just trying to better understand what is going on. I am definitely going to keep the JB4 how it is though. Sorry if this is a stupid question, but could you explain why its always trying to advance timing? I thought the goal was to have peak combustion at 15 degrees ATDC.

    Thanks!
    It stops at some point of course. The idea behind the factory system is to run the timing on a cylinder by cylinder basis in a closed loop mode. Optimizing each cylinder to just below knock threshold. Which gives the optimal power and efficiency. It can do this through new knock sensor technology that was not previously available/used in production motors like this.

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    It stops at some point of course. The idea behind the factory system is to run the timing on a cylinder by cylinder basis in a closed loop mode. Optimizing each cylinder to just below knock threshold. Which gives the optimal power and efficiency. It can do this through new knock sensor technology that was not previously available/used in production motors like this.
    So basically you just want to advance timing as much as possible without knocking? Wouldnt methanol be more effective reducing knock than using CPS offsetting?
    Click here to enlarge


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    Click here to enlarge Originally Posted by Gbreee90 Click here to enlarge
    So basically you just want to advance timing as much as possible without knocking? Wouldnt methanol be more effective reducing knock than using CPS offsetting?
    yes, increasing the octane is always the easiest, and my opion the best way to eliminate knock, but for some reason, "other" people alway want the cheapest way.. which is redundent by their choice of other "mods" on the car. run 93 octane and meth, like me, at 16-18 psi, like me, but they choose to swear up and down about the need for having cps offest, which see like .3 degree's..

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    Click here to enlarge Originally Posted by Gbreee90 Click here to enlarge
    But if you advance timing too far the flame front will try to push the piston backwards during the compression stroke. I am guessing after a second of that happening knock would occur due to increased heat and then the JB4 would retard timing. Is this correct? If so, does anyone know what this point is? Maybe the DME isnt even capable of advancing that far. I would think BMW engineers would take that into account and prevent it from happening.
    ideal timing is not a fixed value but rather it is dependent on engine speed and load. Think about it, you mentioned 15* ATDC as being the ideal time for peak pressure and you are correct(although i've seen 20* also referenced) as this is when the momentum and position of the piston will allow it to take full advantage of the downward force being produced. However the actual moment when the spark must be ignited varies according to how fast the actual engine is moving(RPM'S) and the load this is because even though the engine maybe moving faster the mixture takes the same amount or time to burn so the faster the engine moves the sooner you need to begin combustion. Your first sentence is correct and this occurs with these tunes because the engine is unaware of the actual load on the engine and therefore believes it must advance timing further than is actually necessary. The engine has an ignition map(or look up table its also called) where it finds the correct timing values for the expected load and bases its operations off that. You are correct that BMW engineers would not let that knock occur and they set up those tables specifically to prevent that but we are not going off those tables anymore.

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    Click here to enlarge Originally Posted by Gbreee90 Click here to enlarge
    So basically you just want to advance timing as much as possible without knocking? Wouldnt methanol be more effective reducing knock than using CPS offsetting?
    No, you generally don't want to do that. It's a complicated subject so you can't prune it down to a one liner. But if you were it would be that the DME does a very good job of managing ignition advance without outside intervention.

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    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    yes, increasing the octane is always the easiest, and my opion the best way to eliminate knock, but for some reason, "other" people alway want the cheapest way.. which is redundent by their choice of other "mods" on the car. run 93 octane and meth, like me, at 16-18 psi, like me, but they choose to swear up and down about the need for having cps offest, which see like .3 degree's..
    That is my plan. Im guessing adding meth would put the timing closer to MBT.
    Click here to enlarge


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    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    yes, increasing the octane is always the easiest, and my opion the best way to eliminate knock, but for some reason, "other" people alway want the cheapest way.. which is redundent by their choice of other "mods" on the car. run 93 octane and meth, like me, at 16-18 psi, like me, but they choose to swear up and down about the need for having cps offest, which see like .3 degree's..
    Now this is just silly! Obviously increasing octane is the best method but that should not be a replacement for a good tune. Find me any ignition map from a standalone ecu or a flash that doesn't pull timing as boost increases. This is actually good that the tuners are doing there job and pushing their technology past its current limits to provide the best tune possible. It would be very easy for Terry to say "run meth above stock boost and you'll never knock and when that limit is reached run E85!" instead he is trying to provide a method that uses pump gas to its maximum.

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    Click here to enlarge Originally Posted by Jimefam Click here to enlarge
    Now this is just silly! Obviously increasing octane is the best method but that should not be a replacement for a good tune. Find me any ignition map from a standalone ecu or a flash that doesn't pull timing as boost increases. This is actually good that the tuners are doing there job and pushing their technology past its current limits to provide the best tune possible. It would be very easy for Terry to say "run meth above stock boost and you'll never knock and when that limit is reached run E85!" instead he is trying to provide a method that uses pump gas to its maximum.
    im in no way one to argue on the subject, but perhaps you can make sense of this.

    taking what you and I say above, the guys WITH CPS are seeing 0-1 degrees of offset, at these higher boost pressures, Do you think that is providing any real benefit over no CPS? especially when I have not seen knock/ timing drops in 20k+ miles of logging?

    I realize its about SAFETY of it, but how is any of this "safe"? that 1* is the difference bewteen safe and not safe?

  19. #44
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    Click here to enlarge Originally Posted by Gbreee90 Click here to enlarge
    But if you advance timing too far the flame front will try to push the piston backwards during the compression stroke. I am guessing after a second of that happening knock would occur due to increased heat and then the JB4 would retard timing. Is this correct? If so, does anyone know what this point is? Maybe the DME isnt even capable of advancing that far. I would think BMW engineers would take that into account and prevent it from happening.
    I would think the BMW engineers would take that into account as well. I don't know what that point is but thus far hasn't the ECU adjusted to well with the ignition advance even when more boost is factored in? Shows a pretty adaptive system.
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    Click here to enlarge Originally Posted by Jimefam Click here to enlarge
    ideal timing is not a fixed value but rather it is dependent on engine speed and load. Think about it, you mentioned 15* ATDC as being the ideal time for peak pressure and you are correct(although i've seen 20* also referenced) as this is when the momentum and position of the piston will allow it to take full advantage of the downward force being produced. However the actual moment when the spark must be ignited varies according to how fast the actual engine is moving(RPM'S) and the load this is because even though the engine maybe moving faster the mixture takes the same amount or time to burn so the faster the engine moves the sooner you need to begin combustion. Your first sentence is correct and this occurs with these tunes because the engine is unaware of the actual load on the engine and therefore believes it must advance timing further than is actually necessary. The engine has an ignition map(or look up table its also called) where it finds the correct timing values for the expected load and bases its operations off that. You are correct that BMW engineers would not let that knock occur and they set up those tables specifically to prevent that but we are not going off those tables anymore.
    I thought with more load the burn time is faster because the mixture is so condensed which would result in needing to retard timing. Obviously it would need to be advanced due to increased RPM though.

    Sorry for the kind of OT questions.
    Click here to enlarge


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    Click here to enlarge Originally Posted by Jimefam Click here to enlarge
    ideal timing is not a fixed value but rather it is dependent on engine speed and load.
    This is why I would like to know if the CPS offsetting as implemented is static or adjusts based on load and RPM. No straight answer to this yet.
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    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    I realize its about SAFETY of it, but how is any of this "safe"? that 1* is the difference bewteen safe and not safe?
    This is the main question. Safety as stated so far is an illusion, a marketing ploy. How simple is it to tell people pulling timing is safer? Now how about if you tell them you are pulling ignition timing at the expense of cam timing? And how about if you go even further and state it is as the expense of knock control? Is it a clear issue now or muddied? How do we balance which is safer? Well, most tuners would say the safest thing to do would be to allow the DME to handle what it was designed to handle in the manner it was programmed to.
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    Click here to enlarge Originally Posted by Gbreee90 Click here to enlarge
    I thought with more load the burn time is faster because the mixture is so condensed which would result in needing to retard timing. Obviously it would need to be advanced due to increased RPM though.

    Sorry for the kind of OT questions.
    You are correct and that is why as boost is increased timing needs to be retarded. So to summarize an engine at a given RPM will need to retard timing as boost increases.

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    Click here to enlarge Originally Posted by Jimefam Click here to enlarge
    You are correct and that is why as boost is increased timing needs to be retarded. So to summarize an engine at a given RPM will need to retard timing as boost increases.
    Which is what the stock DME does on the BMW turbo motors.
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    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    im in no way one to argue on the subject, but perhaps you can make sense of this.

    taking what you and I say above, the guys WITH CPS are seeing 0-1 degrees of offset, at these higher boost pressures, Do you think that is providing any real benefit over no CPS? especially when I have not seen knock/ timing drops in 20k+ miles of logging?

    I realize its about SAFETY of it, but how is any of this "safe"? that 1* is the difference bewteen safe and not safe?
    I honestly cannot say how much benefit can be seen by a 1* offset at high boost(my guess is none) what I will argue is that perhaps more offsetting is necessary. As for you not having seen any timing drops in 20k of logging that would seem to be commendable and kind of surprising as I believe you run terrys software and he stated yesterday on another thread that he was seeing timing drops on 13 and 14.5PSI maps. Also I can almost guarantee you that if the DME is compelled to pull timing due to knock it cannot at the higher levels of boost(where the difference between needed timing and actual timing are greatest) pull all the necessary timing at once. The BMW engineers not likely anticipating these disparities almost assuredly set a maximum timing value to pull at once. Meaning that if you need more than whatever that limit is pulled you wont get it till a second knock event occurs. This is hypothetical but I would love for terry or another tuner to confirm or deny whether this is true. If this is the case(i'm pretty sure it is) some timing pulled would be better to none as even though it may not have been enough to prevent the first event it may save you from the second.

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