Load Target Offset (Overboost)

Asian47

New Member
Aug 23, 2023
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Hey guys, just wondering if anyone can provide some information on this table and how it interacts with other tables?

Have read that it may play into HPFP pressure somehow?
Made a single change to the tune and it's gotten better.
load target offset (overboost)

My table was just like every MHD table I can find, most values are 1 and taper as RPM increases.
But looking at JSR tunes, he tends to have it set to 1 everywhere. I can't find a good example of what the table does.
So blindly I changed the whole thing to 1's. Now pressure will drop, it'll miss a little and jumps back to life pretty quick, no lift needed. Before if it missed I had to lift, it wouldn't come out on it's own.

So from what I did find about load target .. it plays into a load adder calculation and it's only supposed to be active in IS codes (overboost). But it's been demonstrated to work in others with tweaks. So I'm thinking something with it worked and reducing with RPM was killing something for me.

And actually the car just all around feels better.

Thanks!
 

carabuser

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Oct 2, 2019
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It's just an addition onto the load target that is applied temporarily. Almost entirely pointless for after-market tuning.

It's there so that BMW can claim higher peak power figures without having to worry about adding additional cooling or causing any extra engine failure. It's used in the Z4 35is and will give an extra couple of PSI for a few seconds then revert to normal load target to prevent excessive IATs due to the crappy stock intercooler. It offers no benefit over adding additional load the normal way.
 
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rebuilt54

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Jan 3, 2024
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fuel pressure .png

would this play into getting hpfp pressure up with n20tmap ? @carabuser
 

carabuser

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Injection quantity is calculated using load. And fuel pumps base their output on fuel quantities.

The problem isn't with the n20, it's with people using tmap scaling manipulation to extend the boost target without correcting the load.
 

salt

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Jan 14, 2024
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Injection quantity is calculated using load. And fuel pumps base their output on fuel quantities.

The problem isn't with the n20, it's with people using tmap scaling manipulation to extend the boost target without correcting the load.
how would you "correct the load" while using TMAP scaling manipulation?
 

carabuser

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how would you "correct the load" while using TMAP scaling manipulation?
That's for the tuner to figure out, it's what separates the good from the bad ones. There's many ways to do it but really most people need to stop blindly scaling the n20 tmap to its full range.

If you are actually producing 25psi then you should be around 240~ load with some assumptions and that needs to be reflected in the tune.
 
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