Boost #'s Explained

[colonel angus]

I started this thread so everyone could chine in on what produces boost, why some trucks produce more than others, how and where to properly measure it and what to look for when it won't hit or hold X #'s.

My hopes isn't for a 70 Page thread, but rather a few very knowledgeable folks share early so we all benefit from their experience.

TIA,

Denny

[Adamv7010]

I've always heard and read the most accurate reading is obtained in the intake tube


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[Willy Mo]

Whats done to your truck has the biggest impact on boost numbers. are you talking stock for stock? modded with stock turbo? larger more free flowing exhaust, larger intercooler, better intake manifold ect can all drop boost pressure. teh more efficient the engine the less boost neede to make teh same power level.

[snopro_03]

In closed loop, the PCM uses exhaust backpressure, manifold and barometric pressures, accelerator pedal position, and engine RPM and calculated load for turbo control.
Changes in parameters for each of these sensors will result in a variation in VGT duty cycle. Higher load demands more duty cycle..... Most always the best place to get and accurate boost reading is on or just before the intake manifold. Essentially you want to take your boost reading at the most end of the charge system letting you know ok my turbo is making it's targeted number and I know I have no leaks in the charge system.

[TwiztedPiff]

how much boost is a stock 04 supposed to produce? i have 4"mbrp no cat or muffler turbo back exhaust. tlas40hp injector tune and pr5r filter with zoodad mod no programmer installed how much boost should i roughly be making?


ohh and for the heck of it... when im on the boost and i let off mid range the turbo goes (woot woot woot woot) anybody know what that is or why its happeneing??

[Tuscany]

That is normal twisted. That is essentially the wastegate for your turbo. They fart back through the intake releasing that excess boost pressure and that is why you hear it.

[TwiztedPiff]

so it doesnt cause damage to the turbo or anything?

[Tuscany]

No that is how they operate.

[TwiztedPiff]

ok good to know. it never did it before until the intake filter was put on and the zoodad mod. so i was thinkning it was related and well hoping it wasnt something i had to worry about. thanks for the info brother.. i appreciate it

[Tuscany]

No problem. Just don't go doing it all the time as that probably isn't good for it lol. It is a function of our turbos though so don't be alarmed.