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BMW 3-Series (E90 E92) Forum
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Just installed Juice Box Stage 2...
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09-23-2007, 08:05 AM | #89 | |
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09-23-2007, 10:20 AM | #90 | |
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PS, you do know that the procede runs nearly the same AFRs, perhaps a bit richer, than the S2 right? Of course you did, which further invalidates this "argument."
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09-23-2007, 11:59 AM | #91 |
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Terry probably has the most miles. I think he probably has around 4000 miles or so logged with the JB2. He has quite a bit of track time with his car as well. There are quite a few cars with it installed and no problems reported so far
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09-23-2007, 01:05 PM | #92 | |
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All of the products bring discussed increase power by increasing boost by increasing resistance to the TMap circuit whether it is plugging directly into the sensor wire like SSTT or tapping into it in pin 10 and 32 in the DME connectors like in JB, Xede and PROcede. Ohms law: I = V/R. Increasing R decreases current which leads to increased boost. The higher the R the more boost you will make. With the JB and JB2 Terry was conservative on the amount of boost being very careful to measure for and stay below the point where knock retard was being introduced. With the JB2 you also tap into the fuel delivery circuit of the DME so as to be able to increase boost above the JB1 still without reaching knock retard. Since you don't really want the linear relationship of ohms law for the fuel enrichment I am assuming rather than a resistor he probably uses a slightly more complex circuit using perhaps paired diodes (semiconductor) to get a exponential delivery of fuel so none or very little under low load/throttle/boost situations and more under higher load/throttle boost. TerryI actually have no idea if this is what is in the JB2 or not and I don't really care since I know it works very well and safely and give conservative amounts of boost, excellent AFR and great performance. The truth is you could probably do it yourself if you wanted to spend the long hours and buy all the testing equipment and risk doing it wrong and toasting your car. Terry did it origionally because he was curious what he could come up and had the knowledge to know where to start. His post that shows you the circuit for the JB1 including the parts is still here somewhere in the forum. But once he did it and realized how well and safely it worked figured he might as well sell it since there will be plenty of folks who would be interested in an inexpensive safe mod that give very nice gains. Basically it is only ignorance on the subject that makes folks perceive it as scary or high risk compared to the other options. |
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