Tsung

Great feedback on your testing and giving my theories a try. Your methods are very methodical and makes sense. My gt28r hybrid twins are coming in from BNR next week, and will attempt to run in in stock ecu with piggyback EManage blue. I have an enlarged ebv bypass pipe and will be having the ebv iron collectors ported to help with pushing the prespool to a higher point. If you are intending on using USDM twin turbos and are interested in the enlarged ebv pipe and aftermarket exhaust manifold that works for both usdm and jdm turbos, I recommend you contact Stu Hagen. You can pretty much google him email him directly. I look forward to what your findings are with the enlarged ebv pipe and larger exhaust manifold. Another thought I have is how you said the transition is closely related to egcv and iacv opening within 100rpm of one another. For prespooling, that would translate to ebv and the one way reed valve to allow boost generated by second turbo to join the intake. Having excess prespool May have the bottleneck at the size of reed valve pathway which limits the boost in which it can sustain before transition.

Great breakdown of the setup for sequential. I have a few suggestions to see if you can improve upon your transition. I see the boost dip from map 27 psi to below 20 psi then back up to 27. That is a big drop and I believe you transitioned too low of rpm for the second turbos to spool up. In your ttc log, you don’t reach 27psi map till after your 3744rpm mark. I would like to see what your graph would look like if you move the sequential transition to start at 3900-4000 rpm and see if you still get that big of a drop in MAP during transition. I am curious because I am in the process of installing gt28r hybrid twins and I see big dips on dyno sheet between 3700-4200rpm as if the sequential went into ttc too soon. Another interesting idea is to keep the egcv transition the same and allow the exhaust gases to pass through the second turbo early to spool up the turbo and open the iacv later at 3900-4000 rpm so the second turbo is fully spinning when it opens. http://www.munroracingturbochargers.com.au/performance.2jzgteTransition DIP.html This site discusses taping into iacv vsv to help with better transition in their hybrid twins set up. Please do some experiment with delayed transition and come back! another issue I see is that ebv should only be active in prespool and turns off when the egcv opens as the exhaust air now travel through the second turbo via exhaust manifold and not ebv.