Discussion in 'Performance & Upgrades' started by Markinter, Apr 13, 2005.
Hopefully it will be there by tomorrow afternoon.
How about de-compression stroke since there is no compression
TEN gallons per hour ??
No wonder you ate your motor!
That is way way off.
Run the numbers.... (DT466 example)
Your cruising 60mph....and, say, 10 mpg. That is only SIX gallons of fuel per hour. And the water should only be 30% of the total, MAX. So that'd be about TWO gph needed at cruise; not TEN!
On a medium-truck, I think it'd be safe to assume (for this discussion) that one is using about half the max-HP to maintain 60mph on the flat; i.e. 100-125 hp. Since the max HP is about 250, even max-power climbing a hill would only need 4gph of water.
I think that if you work for more of a 'spray' than a mist, you will see more of a decrease in EGT's...AND an actual improvement in MPG's. It is the water that evaporates IN the cylinder which lowers the EGT's.
A fine mist which evaporates in the air-stream BEFORE it gets to the cyl's only cools the incoming air a bit. It doesn't cool the EXHAUST at all. Whereas, droplets which are turned to steam IN the cylinder are absorbing COMBUSTION heat, i.e. cooling the EXHAUST gases....i.e. "EGT's"
For best results, go for droplets instead of mist, and "linearize" the system, instead of just having "full/none".
I.e., put 3 small-capacity nozzles in the intake, and 3 microswitches on the go-lever. First nozzle comes on just off of idle....2nd nozzle at just below wherever your normal 'cruise' pedal position is; and the 3rd comes on somewhere near full pedal.
If your truck idles a lot, it'd be worth having the first nozzle on at idle; i.e. whenever the engine is running. (oil-pressure switch). The water-injection definitely helps prevent carbon-deposits; and removes deposits you already have.
Cruise flow should not be higher than 2gph for a truck that runs cruise-mpg of 10. Proportion the numbers to fit your own engine/mpg/truck etc..
I would strongly suggest injecting the water AFTER the turbo, btw.... Injecting prior to turbo will erode the compressor blades, and the blades also smash the water to mist; which will, again, prevent you from getting the EGT-cooling and MPG-improving benefits.
One of the Scandinavian truck-makers....Saab-Scania, or Volvo, did a big study of water-injection a few years ago. The report, or at least an abstract of it, is floating around the web somewhere. If you have access to SAE papers (big-city library, if you don't have an on-line SAE account), that same truck-maker published detailed SAE papers on it.
Actually, water-inj has been around forever. Most any decent ICE engineering textbook or handbook will have a chapter on it with the basics. The on-line archive of NACA (father to NASA) papers from the 1920's-1950's contains several papers on water-injection.
Keep us posted on results Mark! It's a good addition to a diesel...especially as fuel price continues to climb...
. I'm not sure the mist has enough time to evaporate before the cylinder. I agree that 10gph is way too much, the formula I've seen is around 1.5 gph per 100hp. I'm using 3.0 gph on my DT rated at 210 hp. Staging the nozzles at incremental boost levels is the way to go.
I added some alcky to the water today but I haven't tested it yet to see if it's better than straight h2o. I wish there was a dyno around here that would take my truck in.
yah, a dyno's the only way to really KNOW....and wouldn't it be SO nice to really KNOW...
You'd be surprised how much -will- evaporate, under the conditions that were posted; i.e. fine mist produced at high pressure (100+ psi), misted into the compressor outlet, which is a 250-degree hot, super-turbulent 100mph airstream....
If it's injected -prior- to the turbo, it'll probably ALL evaporate prior to the cyls....because the compressor will smash it to super-mist.
There are "misters" for industrial-processes made on the exact same principle; i.e. a rapidly spinning bladed disk, with a jet sprayed into the blades. All that comes out is a fog ...like an ultrasonic humidifier...
I'd look at lawn-irrigation heads, or something else like that, that're designed for 40-50psi and to produce droplets rather than 'mist'.
Or chase down the papers and draw your own conclusions, let us know what you think. I'd be interested in correlation, or refutation, of what I got out of studying them.
Just in case you guys didn't see Rob's article, Click Here. He also has it as a link in his sig now, so you'll find it posted above.
I read his article a few days ago and his DIY kit is right along the lines of most kits found on the net. The major consensus for these kits is higher pump pressure is better for atomizing the water. Whether this is for better control or uniformity of flow I don't know for sure. Most kit marketers say that you should install the nozzles after the turbo but as far from the intake as possible. My thoughts are if evaporation is occuring prior to the cylinder it's still helping to lower egts because it is absorbing heat. It could be less effective but I wouldn't have any idea what the percentages are.
Water injection has been referred to as "the poor mans intercooler" with the same principle of charging the air. Water injection has been stated to be more effective at lowering egts than a IC.
I think lawn irrigation heads might produce a high gph flow rate. My biggest fear is that my nozzle will get loose and fall down into the turbo or get blown into the engine
Banks and many others from what I've read use misting type nozzles so there might be good reasons for mist rather than droplets.
I think Rob's idea of checking the flow of your nozzles prior to install a very good one
I would go for what has been tried and used with the least possibiity of causing engine failure( if there is such a thing)
I'm going to try building my own injection setup. Sounds like I'm on the right track, with a [email protected] pump. I like the staged injection idea, too, if I can find the right solenoid valves to run it.
I think I'll stay simple, first go around, and just get some different nozzles, to play with delivery rate.
I read that Ford was messing around with the idea of piping the A/C from a Lightning SVT into the intercooler on the motor for racing.
I think the principal idea was to build a diverter valve that blows cold A/C air into the I/C to lower charge air temps. When you want to race, you pushed a button that activated the diverter valve and blew A/C into the I/C. The results were astounding from what I remember reading. The SVT concept was dumping 600HP before Ford axed the SVT program last year.
Supposedly it will return in '07.
If the pump's max is 1.6gph you wouldn't be able to run more than 1 nozzle at a time. If your pump puts out say 6gph you could stage the nozzles using 3 boost switches each set to various levels and 3 solenoids that would activate after it's particular boost switches level was met. The diameter of the nozzle's orafice is what the flow will be not the gph of the pump unless the pump is less than the nozzle. Demand pumps will cycle on and off to meet their psi rating and there is no way to force say 6 gph through a 1.6 gph nozzle. I would suggest you get a higher volume pump and then play with the dia. and or amount of the nozzles that way you can add more without having to buy a new pump.
I want to add a indicator light from the solenoid that lights when there is actual flow to the nozzle and maybe a pressure gauge so I could tell whether or not a hose has come off and I'm pumping water/alky onto the hot turbo or manifold which did happen to me
Rob's article is good and I would follow it except that a nozzle that puts out .17 gp minute =over 10 gph that IMO is too much like Dozer has said. That much water can "quench" ignition and worse. Also the use of the thin plastic 1 gallon container may rupture since it looks like its smashed against the pump. This is just a temporary tank just like my washer fluid tank is but I'm still using it . Instead of plumbing into the bottom of my washer fuid tank I cut a hole in the fill cap and ran a hose through it and added a filter to the hose and it stays on the bottom of the tank and just about sucks it dry. 1 good hill will use the whole tank. A 5 gal plastic gas can using the method above should do the trick, just have to decide where to place the container.
You could make an even more simple kit by using just a pump and nozzle and just turn it on when you need it on a hill and turn it off when you want, but you'd have to make sure that your pump and tank are below the nozzle so water isnt drawn into the system.
Start low like you've said . Surflow and Aquatec have good demand pumps.
Good luck and let us know how things are going.
Some of the kits say you don't have to clamp the hose onto the nozzlesand solenoids but you do and the same goes for the boost tube that comes off your intake, mine blew off a few times and I could really hear the turbo then . Here is another good DIY site.
Check them out and let me know what you think
Good feedback guys. As far as the nozzle size goes you’re very wise to start small and go from there.
I definitely don’t think we are in agreement as far as how much water is enough or too much, but that’s good. Those are the kinds of issues these forums are for.
From the folks I’ve talked to, Matt Snow and others, for a 7.3 engine making about 260 hp at the crank, anything less that .15 gpm isn’t going to give you much benefit. They recommended between .15gpm and .3gpm! All of there calculations are based on hp. I started at .25 and could hear noises I didn’t like right away. I cut the system off and went to a lesser nozzle. I believe the IDI is such a high compression beast (hence the line in my sig) only the lowest end of their recommendation is safe for the IDI.
After Travis’s engine failure we exchanged some PMs. If WM injection was the cause, and I think it was, I think the biggest reason was the bigger pump he was using. He had is pump pressure maxed.
Based on some bench tests that I’ve done since. The pump Travis had, set the way he had it set, maintains 220psi. When capturing the mist in a jug, he was flowing between .27 and .3 GPM. Believe me, if you put more pressure at these nozzles, they will flow more water. Much more, I’ve done the testing and seen it happen.
I may be singing an entirely different tune if I blow my engine up tomorrow, but based on my test runs and experience, I’d say the desired range for an IDI is between .13 and .20 GPM.
based on the chart at snow performance http://www.snowperformance.net/files/diesel_installation.pdf
It looks like I am a tad high. According to his chart, which is different than an email conversation we had a year ago, It looks like I should be shooting for .12gpm (451ml pm)
the big firms like Volvo that have done it on real-world trucks have injected the water directly into the cylinder, like the fuel.
In fact, in some cases, -with- the fuel. I.e., they injected a mixed water/fuel emulsion.
This has produced the best MPG/HP gains and EGT reduction. Those are the benefits I'm after; so I will be duplicating that setup as closely as possible; which would be spraying large droplets as close to the manifold as possible.
On the other hand, if your only goal is to cool the charge-air like an IC, then an IC is easier, and it never needs water...
I like the idea of a manual control; because you could use it as a poor-man's "dyno". Hit a section of road that's real 'constant', like a long flat, or a known grade, and flip it on and off 10-20 seconds at a time....any 'worthwhile' difference should be noticeable.
That would also be a good way to test the difference between mist/fog and droplets. Put in 2 different nozzles, and a 3 position center-off toggle in the cab (i.e. SPDT). Run the same tests on the flat and/or grade. If either mist or droplets has a 'worthwhile' edge over the other, it'll be noticeable. Any effect that isn't noticeable, probably isn't worth the trouble.
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