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Setting up open loop boost control table

Boost Control

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Hey Guys - I'm (finally) getting to my boost control solenoid setup. I've been running on waste gate springs up to now.

My constraint is: my boost control duty cycle table is 2D and I can only control the X axis. Meaning Y-axis is locked to duty cycle and X-axis I can choose what I want to control by. Running a Haltech Platinum Plug & Play on a greddy twin Z33.

My question is: should I control duty cycle based on RPMs, Actual Boost Level, Manifold Pressure, or something else?

Thank you for your insight -

Easiest thing to do in my opinion is RPM. So what you do is, you set the whole table to the same value at first. Let's say 30%. Now it's basically a manual boost controller but adjustable on a laptop. You do WOT pulls and look at the boost curve. You've got a 10psi spring and you want 15psi.

30% duty - peak boost is 11psi tapering off at 5000rpm

40% duty - peak boost is 13psi tapering off at 5000rpm

45% duty - peak boost is 14psi tapering off at 5000rpm

So you now raise duty cycle at 5000rpm and up to hold 14psi to redline. Then at this point to get more response you can give it a little bump down low to hit 15psi. So raise duty to 80% up to say 2500rpm and then transition down to 45% over the next 1000rpm or whatever. Now you will have better spool and your peak boost will probably increase to 15-16psi and be relatively flat or with a slight taper.

With this method most of the part load boost is still limited by the throttle, and the rpm based adjustment is mostly for WOT.

Thanks for your response RX

I should probably re-watch the BC course!

I did this over the weekend and it worked well enough - started and 25% and creeped up to 30% and was reaching 16psi gauge/12psi absolute (which is about where I want to be for the time being). A buddy from the 350z forum also suggested RPMs.

Should there be any worry of overspinning the turbos while at higher RPMs, in vacuum, and my WGs are pinned shut? For example down-shifting - TB is shut/BOV is open? Other concerns?

Thanks for your response

I wouldn't worry about it.

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