basic water injection non boosted

[TheVsStig]

i think the pump holds a pretty constant pressure. when i tested it i just wired the pump to the battery, the w injector was just plugged into on of the fuel injector plugs and a bottle of water to feed. the higher the rpm the better the spray pattern, it is almost like the 2nd pulse of water being so far up the ass of the 1st pulse, mists the 1st pulse and then the 3rd pulse mist the second pulse and so on. no i haven't tried running the injector at higher pressures as i don't have the appropriate switch to do so.

btw i think that pump has like a 2psi drop at most before it kicks back in. so i would be pumping up to 17 then dropping to 15 before it pumps back up to 17. when the pump was kicking back in it was bring the pressure back up within maybe a quarter of a second, and i couldn't see any difference at all in the spray pattern when it kicked over. there is a fine tune adjustment on the pump that can adjusted up to +/- 2psi, to make very accurate changes to pressure (i could change from 17psi to 17.5psi if i wanted). also the pump can hold a constant pressure of up to 80psi at 4.3 Lpm

 

[Tsunamix]

FYI Temps measured using a thermocouple in the inlet stream of pot #1.

The problem with pulsation is you do get areas of the inlet stream that do not have mist in them.

I did most of this research myself, then decided the best way to go was to use a constantly running pump, with a recirculate function.

When I did the 308, we used a washer pump from an HQ. it put out about 70PSI, and through 1.06 mm CIG Welder tip, flowed about 150CC in 60 seconds, which is just about spot on for a 650DP at 4000 RPM.

So you start by figuring out how much fuel your running through your syste, On A stock ecotec thats 29lBS x 0.85 (85% duty max) in 3600 seconds per injector. Fuel density is about 720kG per cum, or 1589 lbs per cum. Pay attention Beavis. This works out at about 78.8 Kg in 3600 seconds, or 1.314 Kg per minute.

So your ideal flow rate on a dry day will max out at .1314 Kg per minute and since volumetrically speaking water weighs 1 gram per cc, your target flow rate per minute is 131.4 cc/min

So far so good right ? Wrong. Throw everything away and forget it because this is the WOT rate. What happens at part throttle - say 30% ? well theoretically you only want to be injecting 39.42 cc/min. How are you going to do that ? Injecting more than double the required rate is going to quench combustion, and maybe even cause rough running like wet fuel does. On the 308 we put in a WOT switch and only ran it at 100% throttle which was good for trackwork, but makes it useless for fuel economy.

Thats why I ended up with a staged system. 200 PSI Pump pressure for good atomisation and a variable output aperture at the pump to adjust flow rates without ruining the atomisation. <ine uses boost pressure referencing rather than throttle referencing but it has a similair effect.

Tell him he's dreaming.

 

[Tsunamix]

Please dont use PVC or Nitrile / Rubber based hoses for 50"50 water meth. Stick to Nylon, MDPE or HDPE, PTFE or similair.

If in doubt, use fuel line.

 

[Tsunamix]

FYI the AEM complete kit and tank cost me $550.

Time wise, installation was a bit.....complex. I put a thread up on here about it somewhere...

oh yeah - here

 

[TheVsStig]

"So far so good right ? Wrong. Throw everything away and forget it because this is the WOT rate. What happens at part throttle - say 30% ? well theoretically you only want to be injecting 39.42 cc/min. How are you going to do that ?"

Have you not read the thread properly? the pulse rate is controlled by a injector signal, it will decrease and increase as the injectors pulse faster. all i have to do is find the right line pressure and it will maintain the right mix the whole way through. the way i've got it setup on 17psi it will inject 100cc a minute at wot and 5cc a min at idle give or take a bit (not that it will be running at idle due to a cut off switch i'm mounting on the TB. granted your setup is better but look at the price tag. when i'm finished with mine it will cost me 60-80 bucks, and it could be done even cheaper depending on how creative you want to get.

the whole reason why i have used a injector controlled by another injector is so i have a setup that will maintain an even 1:10 ratio (or a bit less) through the whole rev range. as far as i can see it is the most controlled way to do it on what i've got without throwing money down the toilet. remember this is supposed to be a cheap and fairly simple diy setup for anyone to do, that will give all the advantages of a WOT setup and a cruising vacuum style setup.

EDIT - also by placing the injector in the intake pipe not the plenum i'm hoping it will give a more even distribution of the water through the intake charge (so its not just pulses of water into my manifold). i've looked at flow charts of the plenum to see how the air moves through it, and i think this will make things pretty even and consistent by the time the charge hits the runners. and anything above 2000rpm the pulses are pretty damn close together anyway and at redline it almost a constant flow. and btw 17psi is fine for what i want as it is well before the T/B and the pump easily keeps the pressure up to this and the injector spray pattern acctually gets better the faster it's pulsing.

 

[Tsunamix]

Have you not read the thread properly? the pulse rate is controlled by a injector signal, it will decrease and increase as the injectors pulse faster. all i have to do is find the right line pressure and it will maintain the right mix the whole way through

Actually yeah i did read it thoroughly. if you noticed I said you DON't want pulsation because you will get dry spots in the intake charge. Unfortunatley no matter where you place the the injector you will STILL get dry spots in the intake charge. That means there will be portions of the intake where no benefit will be obtained. It's a bit like having a flapper valve covering an intercooler core. Even if you double the length of the injector pulse (I don't see how, it's already at 85% duty cycle at WOT) then you will still only have 2 pulses per 6 intakes.

Hence me saying go for a 'continuous spray' at WOT by all means, but doing it at part throttle means pulses which means more of your intake cycles will receive no benefit that those that do.

remember this is supposed to be a cheap and fairly simple diy setup for anyone to do, that will give all the advantages of a WOT setup and a cruising vacuum style setup.

Remember that any money spent on something that achieves nothing is more expensive than something that costs 600 bucks that achieves everything thats needed.

No matter which way to cut it, slaving one injector to another is only going to get you a pulse when that injector fires.

I suggest you do some more maths and calculate just how long the pulse is, and how fast your intake charge is travelling, so you can get some idea of how much of your intake charge will NOT see a pulse. Heres a start point. The throttle body flows around 600CFM at 28" of Mercury (1 atmosphere). It's diameter is 69mm. Go to this website, select velocity, and plug in these numbers - FLOW RATE CALCULATOR . The result just over 75M / sec. if your pulse is of 0.2 second duration, your going to have only 15m of your 75m of intake charge with the water pulse present.

**Caveat - since we don't know the pressures involved, these numbers are applicable at 1 atm / 28" of mercury only. But the RATIOS / PERCENTAGES will remain UNCHANGED**

Looking at that result, you can see why I am saying pulsed is not the answer.

My memory says injector pulse width at idle is 15-17 msec. The full table of pulse widths and duty cycles I got from here Technical Database - Engine.

This tells me that 1 injector pulse even at 100% duty cycle will still max out at .25 sec, leaving 0.75 sec of airflow without cooling.

 

[PIR4TE]

I suggest you do some more maths and calculate just how long the pulse is, and how fast your intake charge is travelling, so you can get some idea of how much of your intake charge will NOT see a pulse. Heres a start point.

The throttle body flows around 600CFM at 28" of Mercury (1 atmosphere).

That's more than twice typical measured CFM for an LS3, impossible for a 3.x V6, and I thought it was 28" of water?

You could also download a copy of HP Tuners or ask Ari or someone else here what the actual figures are in the stock tune...

 

[Tsunamix]

Nope. 408" of aitchtwoohh, 28" of mercury.
http://www.convertunits.com/from/inches+of+water/to/atm

Your sort of right on the flow rates. ls1's flow around 250cfm, but that's not at 28" of mercury. It's only a partial vacuum on the suction side, not a full vacuum. You also need to note that i said the Throttle body flows 600cfm not the engine consumption is 600cfm.

But since the intake ports can flow 180 odd CFM PER PORT at 0.5" lift.... http://forums.justcommodores.com.au...cation/63410-v6-head-flow-specifications.html

 

[PIR4TE]

Nope. 408" of aitchtwoohh, 28" of mercury.
Convert inches of water to atm - Conversion of Measurement Units

Your sort of right on the flow rates. ls1's flow around 250cfm, but that's not at 28" of mercury. It's only a partial vacuum on the suction side, not a full vacuum. You also need to note that i said the Throttle body flows 600cfm not the engine consumption is 600cfm.

But since the intake ports can flow 180 odd CFM PER PORT at 0.5" lift.... http://forums.justcommodores.com.au...cation/63410-v6-head-flow-specifications.html

OK fair enough, an engine's theoretical CFM is calculated at (STP) 1 atm, and typically not converted to the 28" water dynamic standard. However flow rate is always at 28" water. Also if an LS1 was truly flowing 250 CFM @ 28" water at the TB then its power would be north of 500HP...

Max flow rate of intake ports at max lift is overstating it as well, no relationship. I'd suggest that given the lack of performance tuning that the Trapped Ve% is at best around 85% (of the Measured CFM minus the Ring BlowBy CFM, minus the CFM lost during the OverLap Period, then divided by the theoretical CFM). Best guess for OP's calcs is 153 CFM @ 28" water.

Meaning OP's calcs are not 25% of target actually rather close, on review.

 

[ari666]

Remember that any money spent on something that achieves nothing is more expensive than something that costs 600 bucks that achieves everything thats needed.

i think this is where your repose derails.

it doesnt achieve "nothing" it assists with fuel consumption... refer back to my first post.

something that costs 600 bucks to do "whats needed" isnt actually needed, thus its doing stuff that isnt necessary.


also sadly there is no chance i could give you exact Ms off hptuners, since all the tables are just scalables and multipliers based off lambda. it doesnt work like a haltech which has a Ms table for injector duty.