Advantages to higher pressure in H2O injection?

payne171 · 12-23-2006, 11:41 PM

In reading the latest issue of Sport Compact Car, part of the article on the Mazdaspeed three grabbed my attention. It seems the extremely high pressure of Mazda's DISI fuel system causes instant atomization of the fuel that absorbs 50-70 degrees from the combustion chamber. This allows for considerable advantages as both an anti-detonation measure and in allowing more oxygen to be stuffed in. So my question is this: would this work for water injection as well? Obviously, water injection does these things already. Would it work better at higher pressure levels?

karl · 12-25-2006, 10:28 PM

higher pressure almost always atomizes better. the only exceptions are when the pressure goes so high that the solenoid holding the fluid back has trouble opening..

i remember when our FSAE team did some research on the effects with normal fuel injectors, running them around 75psi instead of the rated 43, and gained a couple % across the board on the engine dyno (not chassis dyno). on a regular car it would be negligible, but it was worth it on the ~500lb formula car..

AndrewMcG · 12-26-2006, 12:56 AM

The water from a decent water injection system turns to steam by the time its in the combustion chamber anyway. Technically, higher pressure is better but the good systems out there are already at 100psi of water pressure and atomize the water well enough to become steam. Poor water injection systems like Spearco's only shoots water at like 20 psi or so and that is no good, but I see no benefit at all for atomizing the water injection more so than the good systems are already doing.

91mr2n702 · 04-01-2007, 04:40 PM

I agree w/andrew. The good systems(aquamist) already does this.

The high pressure combined with the right nozzle gives you atomization(lowering temps), but they also designed the system to put some small droplets into the combustion chamber to interfere with combustion(act like high octane race gas & allow for more ignition timing to be used safely)

Weasy2k · 04-10-2007, 07:14 PM

I wouldn't buy or build any WI system with less then 60psi...you want water to mist in there not "flow" :P

Aquamist has one hell of a system lineup!

12-23-2006, 11:41 PM	#1 (permalink)
payne171 No Skills Join Date: Jul 2006 Posts: 14 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Advantages to higher pressure in H2O injection? In reading the latest issue of Sport Compact Car, part of the article on the Mazdaspeed three grabbed my attention. It seems the extremely high pressure of Mazda's DISI fuel system causes instant atomization of the fuel that absorbs 50-70 degrees from the combustion chamber. This allows for considerable advantages as both an anti-detonation measure and in allowing more oxygen to be stuffed in. So my question is this: would this work for water injection as well? Obviously, water injection does these things already. Would it work better at higher pressure levels?

04-10-2007, 07:14 PM	#5 (permalink)
Weasy2k 3.4L 10K RPM In the works Join Date: Mar 2005 Location: Vancouver, BC Posts: 8,895 Thanks: 34 Thanked 80 Times in 66 Posts iTrader Rating: (9/100% )	I wouldn't buy or build any WI system with less then 60psi...you want water to mist in there not "flow" :P Aquamist has one hell of a system lineup! __________________ -Johnny @ Sea2Sky Tuning - www.sea2skytuning.com http://www.mr2.com/forums/sea2sky-tu...-out-sale.html

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12-25-2006, 10:28 PM	#2 (permalink)
karl all macgyver on it Join Date: May 2006 Location: robbinsdale, MN Posts: 298 Thanks: 1 Thanked 31 Times in 24 Posts iTrader Rating: (0/0% )	higher pressure almost always atomizes better. the only exceptions are when the pressure goes so high that the solenoid holding the fluid back has trouble opening.. i remember when our FSAE team did some research on the effects with normal fuel injectors, running them around 75psi instead of the rated 43, and gained a couple % across the board on the engine dyno (not chassis dyno). on a regular car it would be negligible, but it was worth it on the ~500lb formula car..

12-26-2006, 12:56 AM	#3 (permalink)
AndrewMcG Its not lag, Its foreplay Join Date: Feb 2005 Location: Albuquerque Posts: 747 Thanks: 6 Thanked 17 Times in 15 Posts My Google Map iTrader Rating: (3/100% )	The water from a decent water injection system turns to steam by the time its in the combustion chamber anyway. Technically, higher pressure is better but the good systems out there are already at 100psi of water pressure and atomize the water well enough to become steam. Poor water injection systems like Spearco's only shoots water at like 20 psi or so and that is no good, but I see no benefit at all for atomizing the water injection more so than the good systems are already doing.

04-01-2007, 04:40 PM	#4 (permalink)
91mr2n702 Try me! Join Date: Jun 2006 Location: Vegas Posts: 98 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	I agree w/andrew. The good systems(aquamist) already does this. The high pressure combined with the right nozzle gives you atomization(lowering temps), but they also designed the system to put some small droplets into the combustion chamber to interfere with combustion(act like high octane race gas & allow for more ignition timing to be used safely)