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Originally Posted by svxistentialist
If you boost the SVX on the stock internals and CR as Phil has done, the additional heat in the charge will tend to cause detonation. When the ECU gets the knock signals, it retards the ignition and adds more fuel to cool things down in the cylinders. As it is not burning the mixture at the best ratio in this mode, you do not get all the power the boost should be able to give.
Phil is probably getting good power because he is keeping the boost low. Using race fuel will also help, less tendency to detonate.
As Mychailo says, the fine water spray mist helps cool the charge, which in turn reduces detonation, and lets the ECU run things without retardation. This gives more power. Water is actually better than methanol, because it requires more energy to evapourate it than methanol does. Thus it absorbs more heat, cools the cylinders better. Methanol on the other hand will improve the Ron rating of the fuel mixture, so is a help to improve the burn rate of the mixture, as well as absorbing heat. For ordinary road use, a mix somewhere between 25% and 50% methanol would be a good compromise, but pure water would be 100% OK at lowish boost levels.
If you are going to very high boost levels, 10-15-20 lbs, the sheer amount of heat you are adding here [which is also a function of the efficiency of your blades, not just based on the pressure you are adding], this heat is not possible to remove by water injection alone, at least not without high pressure pumping of large volumes. This is just not practical.
The sensible route is probably to lower the CR for higher boost. In addition, water injection is probably easier to install on our SVXs for boosts in the 6-10 lbs region, and would not need a huge reservoir. You will probably need both injection and an IC if you go for higher boost levels.
Joe
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+1
I run 3.5-4lbs of boost on pump gas and 6psi on race fuel,just to make sure i am not pulling timing. I ran about 60 miles on 6psi without high octane fuel and experienced no timing retard, but im sure given another variable that would be detrimental such as a hot day, i would most likely make less power with more boost. But, given the way the car is setup now, i really do love taking your same tq curve and then just pulling it up even higher
If i do decided to lower the compression, ill be forced to go with a TEC-II or possibly program in an AEM, as the need for bigger injectors would be imperative. So for now, i cant say WI wouldnt hurt, but im enjoying endulging(and not over endulging) in boost, while keeping my car on the road
phil