What/why exactly does boost creep occur with a free flowing exhaust?
09-26-2003, 09:32 AM
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What/why exactly does boost creep occur with a free flowing exhaust?
noticed here and a couple other places people talking about boost creep occuring with a 3" DP. Is the reason because the pressure differential is so great between the turbine and compressor side that it almost pulls the compressor wheel revolutions upward?
Cheers,
Sameer
Cheers,
Sameer
09-26-2003, 09:54 AM
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It works like this:
Your wastegate is there for the sole purpose of letting extra exhaust pressure escape the exhaust housing of the turbine in order to regulate the boost pressure in your manifold.
If you put a larger exhaust on, the exhaust gas says "hey - it's a lot easier to go out this way through the newly unrestricted exhaust than through the itty bitty hole in the wastegate... Later!!"
Doing this will then spin the turbo faster (as it's now less restriction), creating even more pressure, spinning the turbo faster, etc.
It's basically a case of the wastegate not being able to handle the additional flow of the exhaust with a bigger downpipe.
Make sense?
If you put a larger exhaust on, the exhaust gas says "hey - it's a lot easier to go out this way through the newly unrestricted exhaust than through the itty bitty hole in the wastegate... Later!!"
Doing this will then spin the turbo faster (as it's now less restriction), creating even more pressure, spinning the turbo faster, etc.
It's basically a case of the wastegate not being able to handle the additional flow of the exhaust with a bigger downpipe.
Make sense?
09-26-2003, 12:41 PM
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well, it's adequate for what it's designed for...
... which is stock boost/exhaust flow levels. Once you start making more HP, it's pretty common to see boost creep.
You can get around it a bunch of different ways. The easiest is normally to port the hot side of your turbo.
You can get around it a bunch of different ways. The easiest is normally to port the hot side of your turbo.
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09-26-2003, 02:03 PM
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but if you go too big, I assume you create more lag?
I would like to think the tuners would account for this in slecting turbos and whatever they do with them as they are R&Ding kits.
