Different Approaches on Piggyback Boost Control - Consistency and Safety

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We expanded the capabilities of the standback A LOT in the last few weeks. We will be posting incredible news for this community, platform, and modding scene in the coming weeks. If you thought tuning solutions had cool features before wait till you see whats next!

[Terry@BMS]

You need to be clear about what you desire. Adjusting boost up at high IAT would be adding more air and consequently more fuel so power is maintained but the higher boost that you specified would result in higher temps as the turbo would be spinning faster. Therefore raising boost because of an already high IAT would result in hotter air and more chance of detonation. Additionally lowering boost b/c of low IAT may maintain consistency but you are robbed of the power than a colder intake charge would give you at the same boost.

Most guys I know that tune their cars lower boost or rely on meth to keep temps low when the temps rise but love to drive as the ambient temps fall as the air is more dense, the charge cooler, the timing advanced, and power up.

Raising boost when it's hot out and lowering it when it's cold is absolutely contrary to what you want to do for performance.

It definitely needs to be mapped properly and well thought out. But the basic concept of altering your boost curve based on air density (and VE items such as the VANOS change over) real time is preferred to just picking say 15psi like you might with an old fashioned boost controller and letting power vary as air density does.

On the JB3 we generally run more boost with colder air intake temperatures and progressively less as intake temps increase. We also shift the peak boost RPM in with less density to keep compressor speeds down as the OEM tune does. Users are able to alter those settings in the user interface as well should they think we've gone too conservative.

[Terry@BMS]

I'm not at liberty to disclose all but I can confirm in car controls for map switching-map 1, 2, and valet and code clearing with feedback from the dash about what map you're in and that codes have been cleared. That's all I can confirm ATM but there is more to come and the concepts are really cool.

Very cool stuff! I think it's great to see N54 enthusiasts users have multiple options from respected companies. We're working on similar stuff as well.

[pentaxis]

You need to be clear about what you desire. Adjusting boost up at high IAT would be adding more air and consequently more fuel so power is maintained but the higher boost that you specified would result in higher temps as the turbo would be spinning faster. Therefore raising boost because of an already high IAT would result in hotter air and more chance of detonation. Additionally lowering boost b/c of low IAT may maintain consistency but you are robbed of the power than a colder intake charge would give you at the same boost.

Most guys I know that tune their cars lower boost or rely on meth to keep temps low when the temps rise but love to drive as the ambient temps fall as the air is more dense, the charge cooler, the timing advanced, and power up.

Raising boost when it's hot out and lowering it when it's cold is absolutely contrary to what you want to do for performance.

I think you interpreted my post wrong. My post agrees with this when tuning for performance.

[Sticky]

Admittedly, I don't know the answer.....but if I had to speculate, I would imagine it has something to do with producing smooth and consistent power levels.

I recall reading something along those lines in the N54 technical papers. The stock programming targets a certain predetermined torque level.

My thinking in this regard is that this is not the ideal logic for those seeking to make more power than stock.

I think you speak to that when you say you altered the shape of the boost curve.

But regardless.....both tuner methods work.

Procede takes over with direct control while the JB indexes the stock control system and relies on layers of algorithms and PID logic to shape the stock curve.

I don't have a problem with the stock curve at all. In fact when I run in stock mode, I find power delivery to be smoothest of all.

It's when you start to push boost past stock levels that the tunes start to have problems with conflicts from the DME not being fooled 100% of the time.

Boost oscillation due to throttle closure invoked by the stock safety systems reared it's ugly head and ruined day to day driveability.

Obviously JB3 20 has gone a long way to predict and eliminate those variances, so the current versions are much better in this regard.

But hey! Even procede has just gone through a period of boost hicuups and I have an ongoing little boost burp between 2nd and 3rd on low load when I shift around 3K.

So no one is infallable and it's actually a good thing that both tunes still allow the DME to intervene when it has to, but as mentioned in the above post - you have to wonder whether that's enough when the DME doesn't really know what's going on?

This is all well said, two different approaches.