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Old 02-11-2004, 04:34 PM   #1
Scooby Guru
Member#: 32792
Join Date: Feb 2003
Chapter/Region: NESIC
Location: lincoln, ri
2003 GGA MBP
12.9 / 105+

Question why not use fuel system components for WI?

particularly, how about a walbro 255lph hp pump, which is capable of over 100psi of pressure? they're cheap too--100 bucks! get a fuel tank, mount the pump in it. get an autometer fuel level gauge and mount it in the cockpit for your low water indicator.

combine that with an FPR, plumbed into the intake manifold, and you have a nice rising rate FPR to keep the injection pressure differential steady. if you use the oem FPR, you get the 43psi of water injection pressure, or you could go aftermarket. of course, you would have to plumb in a return line.

complaints about reliability are clearly sidestepped with this approach... if the components are good enough for fuel, why wouldn't they be with water (or alcohol, or some mix)?


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Old 02-11-2004, 04:48 PM   #2
Scooby Specialist
Member#: 43151
Join Date: Sep 2003
Chapter/Region: South East
Location: Charlotte, NC
04 STI
Kinda Silver-ish


Better yet, why not skip the cost and time of installing two seperate systems, and put the water right in with your gas in the gas tank, and turn up your IDC's accordingly! j/k

Sounds like a good idea to me.
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Old 02-11-2004, 05:04 PM   #3
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Location: Stevens, PA
04 STI


Ask ChargedPerformance (Ed) what he thinks. We just installed WI last night and the WI pump is WAY different from a fuel pump.
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Old 02-11-2004, 05:07 PM   #4
Jon [in CT]
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Join Date: Nov 2000
Chapter/Region: NESIC
Location: Connecticut, USA
02 WRX Sedan


If I went through the trouble and expense of adding what is essentially a second fuel system, I wouldn't fill it with water — I'd use xylene or toluene.

Last edited by Jon [in CT]; 02-12-2004 at 09:31 AM.
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Old 02-12-2004, 01:20 AM   #5
Equilibrium Tuning
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Join Date: Oct 2002
Chapter/Region: BAIC
Location: Fairfield, CA
2006 STI


Another issue with using fuel components is that they are not necessarily approved for water. Many fuel components will actually rust internally when used with water (fuel injectors especially).

-- Ed
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Old 02-12-2004, 12:22 PM   #6
Charged Performance
Member#: 40645
Join Date: Jul 2003
Location: Jersey City, NJ

Provided the components were compatible with your selected mixture there is no reason that you couldn't do this. But would the complications of installing a second fuel system (tank, pump, pressure regulator, return line, injector controller) aftermarket be worth the added benefits?

In my view an optimal supplemental mixture injection system would be a rising rate pressure regulated port injected system controlled by a map whose base flow characteristics was tuned to the knock tendencies of the motor and its torque profile. There would be an overlay +/- modifier to the flow amount for cylinder by cylinder EGTs. Add to it a small jet at the turbo outlet that was controlled by the temperature of the induction charge seen at the throttlebody.

I disagree that solely xylene or toulene would be the inherently better option when doing this. With a full blown second fuel system - you could alter the ultimate fuel mix to a knock suppressed optimal mixture without water injection - that I won't deny. But how much would the gasoline fueling have to be decreased and how much *lene would you have to inject to reach this point? Water still has an infinite effective octane requiring much less to be injected then its alternatives for the same effect.

Dispite John Banks' experiences I still have found that until fuel is reduced to optimal AFR water is a better injectable for the knock suppression being sought - though I remain open to learn otherwise. From there I would use methanol due to its solubility with the water and to ensure all oxygen actually was being utilized in combustion.

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