For anything you'd like to see added to Speeduino
#53062
I would like to have 2 separate boost control loops running simultaneously and then have some parameters that allow the ECU to select which loop to use for the boost control output. Each loop could have different input, target, PID, etc.

Seems like one could get away with basically duplicating the current boost control programming and then add in parameters that select between the loops based and maybe have a delay between switching loops.

Sounds simple to me. I'll be working on it myself, but I someone with any programming experience could probably do this quite easily.
#53116
Although useful on a standard turbocharger to help account for environmental changes if you don't have compensations thuroughly tuned, the primary use would be for VNT turbochargers. Boost is still the main target, but the vane control adds some complexity to boost control across all the different scenarios and its useful to have exhaust pressure as part of the control scheme.

Its not as much of an issue if you're always driving at the same elevation and are not running near the compressor's flow limit. If you're going up/down 5000ft and want to hover near the compressor limit, then you need to have your compensations mapped out very well.

You could get away with an exhaust pressure gauge, several compensation maps, lots of logging, and lots of tuning. I would prefer to skip most of that by having exhaust pressure monitored and constantly adjusting for environmental changes.

The control strategy between to the 2 loops would probably be simply use the loop that currently has a lower DC% output.
#53123
So you are actually looking for VNT control?

Why wouldn't you just say that?

Would likely require a LOT of work as it would be all new and additional MAP's, sensor input and output etc.

VNT's are not that popular in the aftermarket so it may be difficult to find someone who would be interested in doing the work.
#53135
Because some people seem to go crosseyed at the mention of VNT and I figured I would try to avoid the debating with people about the 'why' and focus on the 'how'.

'all new and additional MAP's, sensor input and output etc.'. The input and output capabilities are already there in the hardware. Repurposing sensor inputs is something even a non-programmer like me can do. The wastegate output is already there and meets the frequency requirements. Yes it would require another MAP, but that seems simple to duplicate an existing MAP.

Seems to me that all it would require is adding a 2nd boost control loop (A bit of copy/paste/rename) and adding logic so that the wastegate output uses the lesser of the two loop outputs.

You're trying to tell me that it is LOT of work? Maybe, but if that requires a LOT of work then I think I'll try coal mining instead.
#53146
A couple high-altitude Garrett VNT setups I've worked on (think hill-climb) used a second standard wastegate on exhaust pressure with calibrated light springs. VNT controlled for boost target, and the wastegate bled excess pressure. The VNT could auto-correct to maintain boost. Lots of ways to come at this.

As your application is fairly limited, it would be good for a user like yourself to guide dev on it.
#53148
Figuring out the programming myself is next on my project list. I guess I was hoping to hit the easy button and hand it off to an experienced programmer haha. :D

An external wastegate is definitely a must for a compound turbo setup. That is the next step after getting the VNT controller working. A small responsive VNT is nice, but driving +70mph up to 11k elevation requires I a big turbo to back it up. Ideally I would be able to have yet another wastegate control loop to control that external wastegate as well. Though I think I may stick with simple machanical boost control for everything other than the VNT turbo and, like you said, use the VNT turbo to maintain the desired boot target.

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