HE351VE on 1987 BMW (gas) - inspired by lilbb!

[mantonakakis]

Long-term update: didn't do much with modifying the car or the code since the last update. It had been running good, but sitting a lot. A month or two ago I decided to fix a couple small coolant leaks on the car, and it snowballed. Among many other things I've built a closed-loop PID wastegate dome pressure controller, and pretty much totally revised my VGT control algorithm, as-yet untested. Hopefully I'll get a test drive in this evening to see if it's any better than what I was doing before!

[hakcenter]

Nice to see some movement on this

[mantonakakis]

New VGT algorithm mostly working well. Have a one or two little anomalies still, like some crazy VGT actuation when I'm within a short range of boost target. Still needs more tuning, but the algorithm is more model-based (kind of centered on mass flow, engine ECU is running speed density which makes for a decent mass flow estimate). In the not-too-distant future I will be adding pre-turbo EGT and pressure sensors. May work them into the algorithm, may just use for VGT tuning.
Wastegate dome pressure control using on-board compressed air is functional too, which is nice that I can drive both wastegate and VGT algorithms from the same target table on the engine ECU (been running a manual boost controller up to this point, and using the on-board air to hold the wastegate shut during spool, then fully vent the dome to let the manual boost controller take over). However, I still need to do a little refining here. The dead zone of the solenoids keeps moving on me, so even though the PID control is stable and responsive right now, it's still not doing a great job of hitting the targets.

[hakcenter]

Well target boost versus shaft speed is going to limit you.

My truck would hit 40psi @ 110k rpm and lower to 35psi but gain shaft speed to 125k. Total trip to watch happen.

But if max flow isn't sustaining I get it

[mantonakakis]

Well target boost versus shaft speed is going to limit you.

My truck would hit 40psi @ 110k rpm and lower to 35psi but gain shaft speed to 125k. Total trip to watch happen.

But if max flow isn't sustaining I get it

That 40psi vs 35psi change implying that boost dropped but mass flow/power increased?
I'm nowhere near pushing the turbo right now, maximum shaft speeds I'll see are about 90k, running about 190kPa absolute for max boost at the moment (I'm at 6000-6500' above sea level, so this is about 16psi boost above barometric).