When running a MBC with GIAC X, is there a limit to how low I can set boost?
05-16-2005, 09:15 AM
#1
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When running a MBC with GIAC X, is there a limit to how low I can set boost?
Running on the track, I'd like to run with less than 15lbs boost. Will I get throttle cut if I set it that low? Any other problems? Should'a never sold that stock ecu!!
05-16-2005, 09:20 AM
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SEL scaling is your friend. Boost at or near redline is where it really counts.
MBC won't affect that, but SEL scaling will. Adjusting SEL scaling is easier than twisting the **** on your MBC.
05-16-2005, 09:22 AM
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X/XR are pretty friendly when comes to that. I went limp with XR and .94 bar TCD, though.
If people can get away with a .95-1bar TCD on X, they most definitely can actually turn boost down that far without any codes/limpness. Still, boost near or at redline is much more important to lower if you are going to the track. SEL scaling all the way, baby.
05-16-2005, 09:25 AM
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On another note, how did you come to figure that 230mbar overboost is the threshold for TC?
I used to cut throttle on occasion at ~6,000 RPM with this setup:
<img src="http://pictureposter.audiworld.com/69223/block_115-mbc_only-57d.jpg">
As you can see, the overboost isn'e even quite 200mbar.
<img src="http://pictureposter.audiworld.com/69223/block_115-mbc_only-57d.jpg">
As you can see, the overboost isn'e even quite 200mbar.
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05-16-2005, 09:28 AM
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Sure, that'll most definitely work. If you have time, play around with a few different SEL settings.
Set it, log a 3rd gear pull to redline, adjust accordingly. Otherwise, just pick a random # (80% for instance) and go with it. If you are MBC in parallel, no need to even adjust the MBC for the new boost setting because the ECU will follow the lowest setting between the 2 (MBC and N75) at a given RPM.
05-16-2005, 09:30 AM
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Great, I don't actually even have a MBC installed yet. I had it backwards though, I thought the SEL
scaling would throw codes, and not the MBC. Glad I asked before buying!
05-16-2005, 09:34 AM
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Neither will throw codes if used appropriately. I played with SEL scaling on a AMS stage 5 car.....
just for ***** n' giggles.
His MBC was set well over 1 bar. Because he was in parallel and requested boost was lower than the MBC setting, the N75 took over and he was making less than .6 bar ;-)
<img src="http://img.photobucket.com/albums/v654/DocSlow/LOG-01-115-AMS_Stage_5_56_SEL.gif" alt="Image hosted by Photobucket.com">
His MBC was set well over 1 bar. Because he was in parallel and requested boost was lower than the MBC setting, the N75 took over and he was making less than .6 bar ;-)
<img src="http://img.photobucket.com/albums/v654/DocSlow/LOG-01-115-AMS_Stage_5_56_SEL.gif" alt="Image hosted by Photobucket.com">