2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Questions about Greddy ProfecB SpecII

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Old Sep 18, 2005 | 06:15 PM
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Question Questions about Greddy ProfecB SpecII

ok....

what happens if i turn the gain up high, i'm running the stock turbo and the mechanic set it to 30%....

do i have to set the "start boost" at all...?

my turbo will only flow 10.5psi with my mods due too pressure drop, the PSI doesent change from 30% too 50%, does it matter which percentage it's set at although it doesent flow more for the higher?...

thanx....
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Old Sep 19, 2005 | 02:21 AM
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nobody knows anything about this?...
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Old Sep 19, 2005 | 09:41 AM
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Start boost = the point in which the Profec will let the wastegate open, in a 3 digit format. So if your target boost is like mine, 17 PSI, my start boost is 160 or 16 PSI. This gives me optimum spool with no overshoot. The closer to the target boost you set your start boost, the more risk you run of spiking (it holds the wastegate closed longer).

Gain = the amount of oscillation that the wastegate sees.. Too much, and your boost will fall off at high ends, not enough and you will get boost creep.

Generally, once your gain is set, it doesnt need to be changed unless you make large changes to your target boost.

Rat
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Old Sep 19, 2005 | 01:08 PM
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but the problem i have is, the car only see's 10.5psi AT MOST with all my mods and front mount....

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Old Sep 19, 2005 | 01:57 PM
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So how is that the Profecs problem?

If you raise your target boost, you HAVE to increase your Start Boost or the wastegates will open too early.

Read what I wrote before..

Start boost is the boost level that the profec starts to use the wastegates. This is used to help spool by keeping the wastegates closed to the last possible second without spiking. The Closer to your target boost you set the start boost, the more spool you get, but the more risk of spike you run.

Last edited by J-Rat; Sep 19, 2005 at 02:00 PM.
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Old Sep 19, 2005 | 07:02 PM
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sorry i didnt understand that, i had just woken up....

no need to be snappy....

thanx again....
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