Quote:
Originally Posted by Flr Power
Using the minimum of WI to just cool the intake air is alright. My point is that you would normally need to inject way past the dew point to have enough detonation protection.
If you can get away by using the minimum amount of WI to just cool the intake air, it means the engine is not pushing serious amount of power (per liter) or you are running alcohol fuel.
|
I think we are not understanding each other.
When I installed the water injection system never had the thought to inject water into the chamber or at least not enough like you are saying.
If I was making "serious power" I would never inject more water to control the burn but rather retard ignition timing or increase fuel mixture.
Over-injecting water would preserve an engine if it is making "serious power" by reducing/slowing the burn due to a cooler burn plus less air is into the chamber due to now water is instead of air in which it is equals to less power stroke = less "serious power".
Hot Air Temps are the actual danger of forced engines being prone to pre-ignition / un-controlled burn or detonation/knock and that is what water injection should be used for .....nothing else.
Summary :
- Injecting water till dew point into the intake will get you the coolest air that you can achieve.
- OVER-injecting water over the dew point will actually displace air reducing engine air flow. Less air-flow = Less power due to richer mixture
- Over-injecting water would make water condense into the plenum / throttle body etc.. which would be liable to corrosion or even hydrolock if there is excess water formation.
- If Water injected is controlled till Dew point and the Air temps are still high for your tastes (above 40DegC) you need to :
1. Check what is the efficiency of the turbocharger and try to set the ecu to target these efficiencies at various rpms
2. Decrease intake temp by either Air filter position or else pre-turbo water injection
3. If these are not enough, consider using a bigger pump pressure so that water is sprayed finer. The finer the water mist the more difficult to reach dew point = chance of cooler air.
4. If also with big pressure is not good than consider intercooling before water injection but this will cost you spool up time and a laggy engine = to less torque on low to midrange rpms.
Presently my setup is a 1.5L engine running a GT2560R turbo - NON-intercooled @ 16psi and 20DegC Air Temp seeing 35DegC Air Temp.
Next Pre-Turbo water injection to reach target of 25DegC Air Temp.