Water Injection

[Todd T]

I have been allowing my pea-brain to get the best of me again. the latest thing to storm through it, is along the topic of water injection to lower EGT's under high boost conditions. for example 20PSI or higher boost levels or even a little higher 25PSI. mainly to use for those WOT bomb runs down the strip. or to allow me to stay in it a little longer on the highways



I have looked high and dry and found only a few squeeks of it around the web. mainly along the turbo-charged gasser lines.



anyone ever try this?



can any of you give me some numbers to shoot for, as far as pressure(bar) and ML's per minute needed.



I have found a few kits and think i could make up one just as easy, like i said, i just dont know where to start on nozzle sizes and pressures.



should i vary the rate of delivery in accordance to the boost level/s.



how fine of atomization do i need to be safe.



what kind of gains can i expect?



what are the down sides of it? any?

 

[jwgary]

I remember my dad had a water injection system in his Z28. I think MSD ignition made it, but that was more than fifteen years ago and I wasn't very old back then. I guess it worked fairly well. I think he had it because he had a vapor lock problem and he was trying to keep things cool. He was running high 13's with a mostly stock car except for the drivetrain (everything including premium interior was still there) in the early 80's.

 

[Bandit1]

if you know some modified tractor pullers talk to them, from what i understand they run a direct water drip straight into the cylinders. jsut a thought though.

 

[Gonzo 1066]

water question

Water injection is not a mistery, it is a well proven asset for high performance diesels. The most common way to add water is a spray into the turbocharger inlet. That is where the heat and pressure are created. The water flashes to steam in the turbo, lowering the intake air temp. Cooler air is much denser thus carries more oxygen to the cylinders. There is more than a few ways to inject water into your intake. The most common is a simple windshield washer pump and a small sprayer nozzle at the turbo. Injection rate of about a cup per 60 seconds is a good place to start. ALWAYS HAVE A HOBBS PRESSURE SWITCH IN LINE!! You can easly ruin your engine if you inject water into a stopped engine. This switch turnes on the pump at a preset manifold pressure. It is possible to build a very elaborate system, I have favored a 200 psi 12v sprayer pump. On my puller tractor I inject one nozzle before the turbo and 2 after into the intake manifold. However this is a non intercooled engine. You may want to pick up "Hugh Macinnis" excellent "TURBOCHARGERS" book. He has a indepth section on gas engine systems. I do not bieleve there is any reason to inject water below 25-30 psi manifold pressure unless you are non intercooled. IMHO

 

[SlyBones]

I recently asked someone who has one. The problem is you need a large tank or have to get out there and fill the thing every other day. 5 gal plus was mentioned. A small tank 1/2 - 1 gal can be sucked dry is a short time of hot rodding. I supposed that if you used it just at the track, then a small tank might be ok. Of course getting a transfer flow 30 gal fuel tank / tool box combo for the back of the truck would keep fillups to a minimum.

 

[CUMINNTSTRKN]

i have talked to many people about this. they have all said to not inject before the intercooler, here is why. the intercooler will lower the temp of the water and cause it to turn from a mist back to liquid and fill your intercooler with water. you will also lose some hp but egt's will be lower.



jim

 

[DarrellB]

These Guys will know

www.enterpriseengine.com ;If anyone would know it would be them. There is a guy that lives around here that pulls his Dodge and it has water injection but some pull wont let him use it. But I'm pretty sure that enterprise engine set it up for him.



Good Luck and keep use informed.

Big D

 

[Mundgyver]

One other thing to consider with water injection. Volume. Water that is injected takes up volume in the cylinder. The result is that you compression ratio should rise. I don't know how it affects the diesel due to the brute strength of the engine in how it is built. I have seen a gasser blow the pistons right out through the bottom of the oil pan. Study hard before you jump into it.

 

[Todd T]

Thanks Gonzo,



Jim, from what i am reading. the reason to not go ahead of the turbine is due to two things.



1st. the intercoolers efficientcy will drop due to the charge air temp and ambient air temp being closer together.



Note: I dont believe that would be the case in our trucks, our outlet temps are something like 350-400F @ 35PSI and around here the ambient is about 50F right now. and 70-90 most of the summer. again what Jim brought up may play into this though. i have to figure out what the volume of air is through it and try to determine if condensation is a factor or not.



2nd. injecting pre-turbo, the water could cause vaporization, taking up volume in the turbo causing its efficiency to drop or worse yet cavitation from the steam (ooh).



I am leaning toward introducing the water either in the end cap of the aftercooler or somewhere in the intake track before the split to the runners for each cylinder.





I am building some spreadsheets to help me calculate a few things. when i am finished i will share the findings with you guys.

 

[Gonzo 1066]

The right track

I would agree on the pre turbo theory of condensate forming in the intercooler. However the key is to map intercooler outlet tempertures and manifold pressures. If the outlet temperture is above 250 degrees you should be safe. Then set the pump to turn on at a appropriate boost level. I would assume at maximum fueling levels and maximum load 33 to 35 psi would be a good time to start injection. There is no need to have water injected at lower boost levels as the intake temps are quite low.

Adding methinol alcohol to the water does more cooling to the charge air and adds a good punch of fuel. On my 414 ci puller engine it takes about a pint and a half of pure alcohol in 25 seconds. The egt lower about 200+ degrees and there is MUCH MORE POWER. There is no detonation, the dense black smoke is much cleaner and there is MUCH MORE POWER. I agree that constant highway use would take a large tank. I see no need to run water of alcohol on the highway for more that a bit. Compitition would be the appropriate place for intake cooling. Cavitation in the turbo is impossible because the liquid flashes to steam on compression and there is a spray not a solid stream of water or alcohol. Injecting after the turbo is the more complex method but you avoid the condensate problem in the intercooler. The use of a intercooler in compitition diesels is not common. Most compition drag trucks or pulling tractors use water for 100% of the charge air cooling

IMHO

 

[Todd T]

i thought the use of alcohol was just for the gassers. i have some vacation next week and plan to attack this then. i thought i would start off with a 30 gallon spot sprayer with a diaphram pump. it just so happens i have one laying around the garage somewhere.



I believe the pump is good for 60PSI or so. i'll hit up the local farm supply for some nozzles of various sizes. and a good filter.



Gonzo, from what you are saying i tend to believe it would be safe to inject at the inlet of the turbo? i plan to use a pressure switch to activate the injection and i am still trying to figure out the amount of h2o needed. i figured i would put a switch in the cab to engergize the hobbs switch and from there the system would activate when the boost levels were high enough. I think i wil start out at 35PSI and see what it does. the truck can flash up 40PSI and hold 38 through 3-5 gears.



and yes it would only be intended for WOT runs both at the strip and on the street (when needed) after all, any other time i could just let off when the temps got too high.



thanks agian and keep the ideas coming.

 

[RobG]

If I were to setup a water injection system I'd want to have it rigged to the EGT guage so it could be automatically activated whenever the temps rise above a certain point. Even have the injection be variable so that it can inject more water (up to a set point, perhaps based on RPM if needed) as the temps go higher.



This could be really great for us modified guys trying to pull major hills when loaded!!



Rob

 

[Bad340fish]

I would think you would need some kind of check valve in the system. Otherwise 40psi of boost might blow up your resevoir that would suck. Plus your pump would need to be able to overcome your manifold pressure.

Clark

 

[CUMINNTSTRKN]

todd



if all you want is 35psi why not just use boost with a check valve. run your boost into the tank, then you have a unlimited amount of pump. then just get a solenoid and run it off your hobbs switch.





jim

 

[Smoker]

Rob,

I was talking to Scheid Diesel today and they have the exact system you were talking about. It uses a separate thermocoupler and turns the system on at about 900 degrees. Price?... ... a little over a $1000.

 

[Smoker]

Here's another point to ponder on. The props in our turbos spin at thousands and thousands of rpm's. If one was to inject pre-turbo, you would run the chance of water build-up in the intercooler and you might eventually observe degradation or warping of the turbo fins. Unless the water was injected at a very, very fine mist, you might run the chance of hurting your turbo. I have heard of stories where fins have been wore down due to injecting pre-turbo. It would probably be best to drill a hole in the air-to-air pipe on the outlet side of the intercooler. Drill the metal pipe and put the nozzle right after the rubber boot. This would give the water ample enough time to vaporize with the heat of the charged air before it reaches the intake. It would give enough time to let it spread out evenly with the hot air.

 

[Todd T]

good point Smoker, that is what i was thinking up front on this. the water only makes up about 3-7% of the total intake charge. a cavitation threat does still exist though.



what I'm finding is that i will need about 450ml/min of water.



Jim, the backpressure from boost should not backfeed the system the nozzle is only 1. 5-2. 0MM + the container would have to be vented to allow it to empty. its not a sealed system. the nice thing about it is if i run out of water i just cant stay in it as long, no harm to the engine will be incured.



Rob, the system could easily be adapted to run off of temps. just wire in a temp sensor with the hobbs meter for activation. or stage two or three injectors for the same effect. i dont have a variable speed pump right now so it will just have to workoff boost for now. i could even wire a pressure switch into the pump so it would shut the system off when the water ran out.



i will start with my pump and tank in the bed, once i get the amounts and starting points worked out i will build a tank and stick it under the bed and hide the pump under the hood somewhere.



Guys, this system wont cost anywhere near $1000. 00 anyone that is willing to pay that send the check to me. and ill send you a kit LOL.



OK one last chance, let me take a poll:



1. should i put the injector in the inlet tube?



2. should i put the injector in the outlet tube?



3. should i put the injector after the intercooler?

 

[Todd T]

I just found a killer site on the very topic.



www.aquamist.co.uk/



man, Rob they have a kit for what you were talking about its $850 but looks awsome.



the basic kit is decent too at $450 but i know i can buiild that for less. using a sureflo pump, some nozzles from the farm supply and a nice aluminum tank.

 

[Gonzo 1066]

h2o injection

Again the only reason that the turbo intake would be a problem is when the outlet temps are below boiling. If you calculate your delivery at 1 pint per 30 seconds that would be a starting point. . One more reason to mix alcohol in the water is freeze protection. A 50% mix will prevent freezing and add extra power.

Most farm sprayer nozzles are two large to atomize enough at the intake but will work well before the charger. Most farm supply stores have a good selection of sprayer parts, (try Farm & Fleet) MAKE SURE YOUR NOZZLE IS FASTENED VERY SECURLEY If the 5. 9 would inhale a . 50 spray nozzle you will be very unhappy. Typical of before turbo injection is to drill and tap a hole into the aluminum snout of the turbo and have a thredded nozzle thredded into it. Just went to the aqua mist site, Very interesting!! The prices are listed in british #s though.

 

[Todd T]

i just got back from Rural King, i didnt find anything that looked worth trying. i will hit the farm and tractor supply close to me to see what they have.



Gonzo, any idea of where I can get a threaded type nozzle in a few different sizes?