The following is an explanation of how and why the Boost Enhancer works. Once you understand the basics of the 951 waste gate system, you will see the necessity for the Boost Enhancer.
The waste gate is the device that regulates the speed of the turbo, otherwise with enough pressure the turbo would over-rev. This is a bad thing! There is a diaphragm in the waste gate that contains the pressure and opens an exhaust valve inside that relieves excess exhaust gas pressure to slow the turbo down. This basic concept is used on virtually all turbo charged applications. The waste gate has a connection to the intake system that feeds boost pressure to it. This is the basics of how the system works. The “Banjo Bolt” on the boost tube is where this connection to the waste gate takes place.
Most people, even factory mechanics, are not aware of this fact: The factory design of the 951 waste gate opens it as soon as any pressure is introduced. It might be barely open, but open none the less. The higher the boost pressure goes, the more it opens. The problem is it is dumping valuable exhaust pressure to drive the turbo, before it has to! More boost at a lower RPM means more torque and horsepower in that RPM range.
Who knows why Porsche did this! Personally it think they did this so the car would be slower and a little easier for the average person to drive. Remember the 951 was the bottom end of their line of cars, they didn’t want it to be the fastest!
The solution to this problem is to slow or completely stop the air signal to the waste gate as long as possible. Most of you with stage 2 software have the modified “Banjo bolt” that was supplied. This device has a restriction jet that slows the boost signal to the waste gate. It works well, but it only slows the boost reaching the waste gate. Why not stop it all together?
That’s where the Boost Enhancer comes in. This device does exactly that, it stops the boost signal until a preset pressure is reached, then full boost is applied to the waste gate and factory systems operate normally from that point on!
It's not intended to allow you to build higher boost pressure, but to give you your normal level of boost much sooner. Once the Boost Enhancer is fully open, the factory controls for timing, fuel, knock control and maximum boost is still there, it is not intended to over ride them.
Factory setting on the Boost Enhancer is 10psi. It requires 10 pounds of boost pressure to start to open it. The higher the pressure it receives, the further it opens and the more it flows air to the wastegate.
We highly recommend that if you have the “Banjo bolt” with the air restrictor, remove it and install the factory bolt! The reason for this is that once the Boost Enhancer opens, you need to get the boost to the waste gate as soon as possible. There is no more reason to delay it any longer!
For street applications, there is really no advantage in changing the factory setting of the Boost Enhancer. We have already set it at the optimum pressure for safe operation. The speed of the turbo increases exponentially. In simple terms, the time it takes the turbo to build 4psi, it can go from 4 to 16psi just as fast. So if you set the Boost Enhancer to high, the turbo can spin up so fast that it could over-boost. The Factory computer will shut the engine off if this takes place, so you won’t blow the engine. The 10psi-factory setting gives the waste gate time to regulate the turbo like it needs to.
If you have a racecar running significantly higher than normal boost pressures, a slight gain might be had by “Tweaking” the setting.
The following is an explanation of how to adjust the Boost Enhancer.
We like to see the Boost Enhancer pressure set at 5psi less then the total boost you normally run. Lets assume you run 15psi of boost, thus we set it at 10psi. That allows a 5 pound window of time for the signal of air to open the wastegate properly and eliminate overboosting or boost spikes.
The housings of the Boost Enhancer screw together like a nut and a bolt. Right hand threaded. Once you loosen the "Jam" nut (the thin red nut) from the Inlet Housing (Blue Housing) you can screw the Outlet (Red Housing) in and out freely. One revoloution equals approximatally 1 psi of pressure. Tighten in (clockwise) one turn for one additional pound or pressure and loosen (counter clockwise) one turn to lower one pound of pressure. Two turns equals two pounds, etc... etc...
After turning the housings to desired position, you need to tighten down the "Jam" nut back against the Blue Housing. This locks the two housings back together again.
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