Profec-B II Boost // problems - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

slider2828 · 04-21-2006, 10:10 AM

I think around 12lbs of boost, it would be on the upper end of your set and gain range. About 42% set and 22% gain. That is about where I have it. But a T25 will have that sort of boost curve because you are pretty much running close to its efficiency and secondly, the T25 with std actuator will not manage a flat boost curve at this level. The exhaust backpressure is rising at higher revs, causing the boost pressure to drop. The only way to combat this is to use the Profec-E01. The difference is that with the profec e-01, you can actually increase the SET% based on RPM. So if you know that your boost is dropping off, you can increase the SET% at the RPM that the boost starts falling off. This feature is called RPM offset. Not really much you can do..... Screw it increase boost to 13.5 which is around 46% SET. Other than that either a profec-e01 or bust. Wouldn't even bother changing the actuator. Good Luck

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04-21-2006, 10:10 AM	#1
slider2828 Post Whore! Join Date: Oct 2004 Location: San Francisco, CA Posts: 6,040 Trader Rating: (13) Feedback Score: 13 reviews	I think around 12lbs of boost, it would be on the upper end of your set and gain range. About 42% set and 22% gain. That is about where I have it. But a T25 will have that sort of boost curve because you are pretty much running close to its efficiency and secondly, the T25 with std actuator will not manage a flat boost curve at this level. The exhaust backpressure is rising at higher revs, causing the boost pressure to drop. The only way to combat this is to use the Profec-E01. The difference is that with the profec e-01, you can actually increase the SET% based on RPM. So if you know that your boost is dropping off, you can increase the SET% at the RPM that the boost starts falling off. This feature is called RPM offset. Not really much you can do..... Screw it increase boost to 13.5 which is around 46% SET. Other than that either a profec-e01 or bust. Wouldn't even bother changing the actuator. Good Luck