When to trigger on injection?

[megavar]

Hi guys,

I currently have a 2D with DDS3 set to turn on at 12psi (minimum) and is injecting 75:25 meth to water. The car has a peak boost of 26psi so the injection is on a fair bit of the time. I seem to remember reading that it is better to activate the WI much closer to the peak boost (and I doubt whether it is necesary below 18-20 psi on my vehicle). Would this early onset be slowing boost rise or causing any other negative effects beside additional meth/water consumption?
Your input would be appreciated.
cheers

Matt

[Dust]

If you are concerned about how much you use, then think about how much boost you see. How often to you see 12 psi? How often do you see 12 PSI but don?t get to 18 psi? If you have a logger or tuner, or anyway to monitor knock on your setup, see how the car responds to the increase in turn on pressure?

If you see 12 psi at ?-3/4 throttle, and that all you give it a lot, then it may help you reduce usage by upping the turn on, but if you only see 12 on the way to 26, then I don?t see it doing anything bad, and actually gives the spray a chance to get in there before it is really needed.

[keithmac]

I turn mine on at 9psi, I have a safe tune up to 8psi (wastegate pressure) and a more agressive tune starting at 11psi which needs water/meth injection active.

Depending on how quickly your car builds boost it may be good practice to keep it at 12psi to cover the "lag" time for the WI as Dust said. I have a 1-2 second lag between pump active and the mixture actually hitting the combustion chambers and affecting the AFR and the two small turbos 9b spool up very quickly.