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Discussion and questions related to the course EFI Tuning Fundamentals
I have a 2JZ swapped into an E46 BMW. Daily driver. The engine is a stock twin turbo in sequential mode, ECU is Link G4+ Storm, and I've got smart coils. Beyond that nothing else done to the engine.
I've had a HKS GTS 8550 centrifugal supercharger in storage for some time and I was toying with compound charging the 2JZ as follows: Turbos to Intercooler#1 to Supercharger to Intercooler#2 and then intake. The goal obviously is more boost, but I was hoping also to get earlier boost too. In the stock twin setup, Turbo#1 kicks in about 2500 RPM with 0.5 bar and Turbo#2 at 4000 ish with 1 bar. Am I wrong to assume the turbos will probably kick in earlier and with higher boost levels in the compound setup? I realize this is centrifugal which is not great at lower RPM, but I'm thinking the compounding effect will still be significant and I'll have both a more responsive and more powerful engine.
The supercharger is generally used in kits for the big Lexus V8 and Nissan 3.5L V6. I've attached the power and torque curve for the Nissan VQ53DE with this supercharger (from HKS website).
Would love some opinions. The HKS supercharger is already with me so it's not a cost (if anyone suggests buying a large single turbo etc). As to why I want to do this: the same reason for the engine swap, for the fun of it.
Normally this kind of compound charging on a gasoline engine use pretty sophisticated controls to have a smooth torque curve, incorporating things like electronic throttle and electronic boost control. I think you'll find that the controls will be difficult with 3 boosting devices. Consider how complicated the Supra's boost controls are already. Have you considered a modern single turbo first (doesn't have to be your standard Supra sized monster), and then maybe consider an Eaton TVS style roots blower (similar to what's on most factory superchargers)? That's what Volvo uses on their twin charged engines.
You may want to check this out:
Sort of compound charging with electric turbo.
Thanks for the info!