quote:I understand what you are saying, and I agree that, according to the law of equilibruim (fluid mechanics), a high pressure source will always exhaust to a low pressure source. This is what you are referring to with the larger exhaust. The "back pressure" (which incidentally does not exist, you are referring to a resistance to flow), is reduced because of a larger pipe diameter. I totally agree. However, keep in mind that the pressure on the other side of the wastegate is at atmospheric pressure, (1 atm, or 14.7 psi, standard atmospheric pressure at sea lever, which may vary if you live in the mountains). Taking into relation the pressure in the exhaust vs. the pressure outside the wastegate, your exhaust will always first flow out the wastegate. Now, let's also keep in mind that an outlet can only flow so much volume of air at any given pressure (PV=nRT). While you increase the volume of air through your exhaust, you have not increased the diameter of your wastegate to allow the excess to vent to the atmosphere. That brings me back to the earlier point, which was that increasing your wastegate diameter will prevent "boost creep". The problem arises not because the exhaust "chooses" to flow through the exhaust piping, but rather because the wastegate is unable to vent the proper volume of air.
Originally posted by scooter:
i was trying to put it in simple terms. so its because the exhaust can not flow out he wastegate huh? well i wonder if its because its to easy for it to flow out the turbine hole instead. yep, i believe so. when you have backpressure, its easier for it to come out the wastegate hole. meaning that the exhaust going out the turbine hole is getting backed up, so some pushes out the wastegate, which keeps the wheel from spinning as hard. if its real easy for it to all go out the turbine hole, it just bypasses the wastegate and all goes through the wheel, which makes it build more boost, and this is boost creep. also you never said i had a false view, spoulson did. im not trying to be a dick to you and i know its hard to admit when youre wrong, but im not the only one with this view on boost creep. you even say the only thing a 3in will do is add more flow to the turbine. well you think it can add so much that all the exhaust just starts bypassing the wastegate, well i and some others here do.
If anyone thinks this is wrong, please let me know.