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Why does 20 psi @ low rpm = more load than high rpm in SD?

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Old Nov 10, 2012, 06:45 PM
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Why does 20 psi @ low rpm = more load than high rpm in SD?

I see this all the time, if I floor it from a low RPM I hit higher load cells than if I floor it from a few thou higher. Is load calculated VS rpm?

Im trying to understand how I will make a load based boost control work, but first I need to understand what the difference in load vs psi is, let alone Im on SD so load= psi, but .. its definitley not the case!

Last edited by 211Ratsbud; Nov 10, 2012 at 06:48 PM.
Old Nov 10, 2012, 07:44 PM
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You're making the engine work harder by flooring it from a lower rpm. Someone correct me if my explanation isn't making sense as it is late and I have worked too many hours in the last 2 weeks.

There is more exhaust energy for longer the lower the rpm you begin your pull from. The difference in a pull for me from 2.5k and 3k is a difference of 10 higher load @ 500rpm sooner @ 2.5k.

Hope that helps a little.
Old Nov 11, 2012, 09:11 AM
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Boost (and load) will slowly creep up on my BBK if I give it a good amount of gas below 2500 rpm in say 4th gear, but once the turbo hits its efficiency range, I see the same boost and load regardless of where I got on the gas.
Old Nov 11, 2012, 01:22 PM
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FMFL!!!

Ive been skimming through my SD rom and I happen to notice that my Map V was not 1;1 with my kpa. I know I changed this 1:1 before, but I must have went back to a rom one day unknowingly. This might explain a portion of the problem Ive been seeing.
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