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  1. #1
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    JB4 CPS dyno testing and logs

    Hey guys,

    Did a little dyno testing today with the new JB4 CPS module. Mainly to confirm what I've been observing during street testing and to quantify the numbers. In summary the results went about as expected. To clear the knock threshold and avoid drops much more CPS had to be offset than anyone performance oriented would want. Ultimately I'm still not sold on any significant benefits but understand that many of you want CPS and remain committed to providing you the product.

    Testing was done in our 135i with full bolts ons, using 91 octane fuel. In theory the CPS offsetting should benefit us 91 octane users more than 93 octane users so this represents somewhat of a "best case" scenario for the offset. To keep things consistent map 2 was used for all runs with this first round of testing. Map 2 (14.5psi) represents an "aggressive" map considering the 91 octane. Temps were in the 50s and the only thing changed between runs was the CPS offset amount. Several runs were done in each configuration and an average/representative run was selected to avoid data overload.

    CPS is mapped on boost and RPM on a preliminary basis and then globally user scaled from 0-100%. Giving us an easy way to compare various offset amounts. Ignition advance represents what the DME thinks timing advance is while CPS represents how many degrees of negative offset/retard are being applied. If you're interested in the actual timing advance you would subtract CPS from ignition advance.

    First up the no CPS run. About as expected given the 91 octane with timing dropping off at 4200rpm (VANOS change over) and once more at higher RPM. Despite this the power curve was smooth and strong.

    Click here to enlarge

    Next up I added a moderate amount of offset amounting to 2 degrees down low and 4 degrees up top. Similar to what others run. Despite this the timing drop at 4200rpm was still present, only not as severe, and strangely a new timing drop cropped up at 6500rpm. Power was largely unaffected as we're still apparently operating under the knock threshold.

    Click here to enlarge

    Given the drops at 30% I moved up to 50% hoping to stomp them out. Unfortunately, very little changed aside from output being slightly reduced.

    Click here to enlarge

    Finally at 60%, 4 degrees offset down low, and 8 degrees offset up top, I was able to eliminate the drops. So the knock threshold value appeared to be somewhere between 50-60% given this boost level and conditions. Although the timing curve "looks great" power took a huge hit. Which is exactly what I've been feeling on the street. Offset enough to reduce the drops and the car becomes a complete slug.

    Click here to enlarge

    For the sake of thoroughness I did a run at 75% offset and was surprised by the result. With 10 degrees of offset, running around 2 degrees of actual advance at 6500rpm, another drop. Crazy. Power also really took a dump with this huge offset.

    Click here to enlarge

    I did a run at 100% as well which I can share if anyone is interested. But with negative timing the whole run the power curve was quite odd and a good 80whp down from no offset.

    Here are the actual dyno runs for each of the logs above.

    Click here to enlarge

    Just to get a few more datapoints I did a few runs on map 1 (13psi) with 0% cps, and with 25% cps, to see what benefit there might be for the average map 1 91 octane user. The 25% CPS did help stabilize the advance but surprisingly both runs were almost identical on the dyno.

    Click here to enlarge

    Click here to enlarge

    The dyno runs for those two logs.

    Click here to enlarge

  2. #2
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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    To clear the knock threshold and avoid drops much more CPS had to be offset than anyone performance oriented would want.
    I'm still soaking this all in but does this not prove that CPS offsetting has a negative effect on the way the factory knock control operates?

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I'm still soaking this all in but does this not prove that CPS offsetting has a negative effect on the way the factory knock control operates?
    One dataset doesn't really prove much one way or the other but I was certainly hoping for more conclusively positive results. =/ We'll see how further alpha testing on other cars go.

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    So let me get this straight, retarding timing reduces power?!? The point of pulling the timing is preventing knock and being able to turn up the boost where you would otherwise be knocking isn't it? What I'm asking is if your running 13psi with no knock then why add the cps. If you are knocking then you shouldn't be running that boost without cps regardless of how much that lowers hp. At least that's how I understood it's use but maybe I'm wrong.

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    The idea behind this testing was to hold variables constant and evaluate the CPS's effect on "knock" reduction. I use quotes as 3 degree dips in cylinder 1 are popularly regarded as knock. But it's an adaptive timing system and can be a very complicated subject. It's worth noting all in all the best performance at both 13psi and 14.5psi was had by doing no offset and letting the DME advance up to knock threshold as it does with a factory stock car. If there was real knock there power would have been obviously lower. But it wasn't.

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    . It's worth noting all in all the best performance at both 13psi and 14.5psi was had by doing no offset and letting the DME advance up to knock threshold as it does with a factory stock car. If there was real knock there power would have been obviously lower. But it wasn't.
    This is key.

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    Click here to enlarge Originally Posted by Jimefam Click here to enlarge
    The point of pulling the timing is preventing knock and being able to turn up the boost where you would otherwise be knocking isn't it?
    Yes you want to pull timing to prevent issues but offsetting CPS isn't necessarily the way to go about pulling ignition timing. At least, it certainly has not been established that is the best way to do it on the N54.

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    Terry, you are offering CPS because part of the market demands it. You have the ability to flash or at least could in limited fashion.

    I know this isn't on your radar, but why not reduce timing through a flash and have that work in concert with the JB4? Why not have a flash file just for timing that correlate with maps? A hybrid setup if you will.

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    I agree it's at best a half assed way to do it. Is there currently any other way of controlling ignition timing.

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    Making a CPS module like this took a couple late nights. It's pretty easy work. Supporting a hybrid piggyflash among all those various ECU versions would be a complete nightmare. Not to mention the end results would not justify the effort.

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    Click here to enlarge Originally Posted by Jimefam Click here to enlarge
    I agree it's at best a half assed way to do it. Is there currently any other way of controlling ignition timing.
    Yes, through a flash but this is the only way for the piggy's to do it. Basically, they are limited but also have their advantages (cost + ease).

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    Making a CPS module like this took a couple late nights. It's pretty easy work. Supporting a hybrid piggyflash among all those various ECU versions would be a complete nightmare. Not to mention the end results would not justify the effort.
    I know, I'm just thinking outside the box. Ideally, I think a flash setup would be the optimum way to handle it but isn't very realistic from a time/cost point of view.

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    Click here to enlarge Originally Posted by Jimefam Click here to enlarge
    I agree it's at best a half assed way to do it. Is there currently any other way of controlling ignition timing.
    You can intercept and delay the coil signals but takes special hardware. With flash mapping you can similarly adjust the advance limiters but wind up in basically the same place. Less the potential injection/VANOS side effects.

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    So just to be clear, all the offsetting does it delay the signal by whatever degree, right?

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    That's all retarding the timing is, changing when the ignition occurs in the compression cycle.

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    Right, negative offset relays the crankshaft position sensor signal. Positive offset advances it. Advancing it is a bit trickier as you have to model the crank and predict when the missing tooth is coming along. But in early bench testing I'm pretty sure this processor can keep up with it. When time permits I'll work on revising the firmware to allow advance as well but at the moment it's a low priority.

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    You can intercept and delay the coil signals but takes special hardware. With flash mapping you can similarly adjust the advance limiters but wind up in basically the same place. Less the potential injection/VANOS side effects.
    its clear that a flash is the most complete solution. Problem is that all these canned flashes are usually just for a stock engine and it's very difficult to find someone to create a custom flash for specific mods. When flashing the ecu becomes easier it will probably be the lions share of the market. I see what your saying about the VANOS side effects but what injection side effects do you speak of?

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    It's a direct injection motor and does up to 3 fuel injections per cylinder. As you fake the CPS signal those injections also move a proportional amount.

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    Click here to enlarge Originally Posted by Jimefam Click here to enlarge
    That's all retarding the timing is, changing when the ignition occurs in the compression cycle.
    Yes, but how the CPS does it is different from it being as simple as just retarding the ignition timing.

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    Click here to enlarge Originally Posted by Jimefam Click here to enlarge
    its clear that a flash is the most complete solution. Problem is that all these canned flashes are usually just for a stock engine and it's very difficult to find someone to create a custom flash for specific mods. When flashing the ecu becomes easier it will probably be the lions share of the market. I see what your saying about the VANOS side effects but what injection side effects do you speak of?
    Custom flashes are available and several tuners do it. The problem thus far has been limitations in the performance of flashes compared to the piggybacks as well as cost/time.

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    It's a direct injection motor and does up to 3 fuel injections per cylinder. As you fake the CPS signal those injections also move a proportional amount.
    Ahh ok. I thought since the N63 doesn't use VANOS I would be free of any side effects if these piggy's were ever implemented for it. That could be more likely the culprit of the misfires than the VANOS adjustments no?

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    It's hard to speculate. Maybe after more data is collected.

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    Terry. Would you say I'm safe running map 2 with FBO and quality 91 oct? I hate cali gas............

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    It's hard to see since I'm on the iPhone but it would seem something between 50-60% would be ideal. The power drop off at 50% wouldn't be too bad to have some added protection against knock. Let's assume for a moment that as you say the drops(which I can't see right now due to my phone) aren't really knocking, at 50% cps offset the dme would be in a better position to handle "real knock" as the timing would need less retarding to get below the knock correct? The difference at 50% is 4hp and 9wtq.

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    Click here to enlarge Originally Posted by Jimefam Click here to enlarge
    Ahh ok. I thought since the N63 doesn't use VANOS I would be free of any side effects if these piggy's were ever implemented for it. That could be more likely the culprit of the misfires than the VANOS adjustments no?
    I think you are confusing VANOS and Valvetronic.

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