I'm in the process of installing my homebrewed water injection unit on my 6.5TB.(Among other things) Buying a unit pre-done is not a option, its just not my style!(got lots of fittings,precision pumps,sensors,etc.. from work to help me out!)One thing that I cannot find any clear answer on is the question of pre or post turbo?


From what I read the pro's and cons of injecting the water pre-turbo are as follows:


Cons:Injecting post turbo can cause damage to impeller if not properly atomized. (Big droplets)


Injection nozzle could fly off wasting your turbo!(A thought of mine!)


PROs: Said to actually cool the turbo extending life of bearings.


Turbo helps atomize water better.


Easier to install as water does not have to overcome turbo boost pressure.(Can use boost to pressurize tank and force water in eliminating need for high PSI pump)


Injection nozzle could fly off wasting your turbo but in turn sacrificing itself for your motor!(A thought of mine!)


I am thinking of doing it pre-turbo (For ease) but would like to know if anyone else has done this pre-turbo and what their expiriance was! (Good or bad)

I'd say post turbo, you don't want to cool it till it passes the turbine.
Post some pics.

W.M.I is used in place of mechanical charge-air cooler to reduce hi temps out of turbo compressor.


If inlet temp is reduced by 10deg, outlet temp will be reduced by same amount. Where inlet temp is 90-100deg, outlet temp can easily reach 300deg at only 10psi Boost.


Reducing inlet temp from 90 deg to 80 deg can reduce outlet temp from 300deg to 290deg.


Would not remove much heat, if water vapor was compressed along with air.


Reducing outlet temp from 300deg to 80deg will net more oxygen per unit volume, to which you can add more fuel, for more power.


And, that is the tricky part, matching injected vapor pressure to varying levels of Boost pressure.


It can be done - we have the technology


Check out Bill Heath's site - he pioneered the tech for 6.5l trucks back in the '90s, developed a working unit, sells a tailored package for Dodge, Ford, GM, others.


And, he's friendly - will explain all.

I have Heath's unit on my truck. It is built a lot different than I was expecting but it does work.


I can't get it to lower the IAT below 120 degrees.(even running more water than he recommends)


It also lowers my water temperature 5 to 10 degrees which really helps on my truck.


The only bad thing about it is having to fill the water all the time. Pulling the trailer with 10 round bales on it on the back roads uses more water than fuel and I only have a 5 gallon water tank. I ran out of water on the last trip home today and had to turn off the AC and slow down to keep the temperatures down. (coolant and EGT)

Burning turbos is not an issue. Compressor side turbo bearing never fails from overheating, Exhaust side suffers the most. Suggest after the turbo. When you inject before you also reduce the amount of air that can enter.

That makes sense when you say it is more effective at cooling the charge post turbo as there is no influence by the turbo. May have to go with post turbo it sounds like.


whatnot, with that 5 gallon tank do you run the injection continuosly or hooked up to a boost switch? Since I have a big truck I figured at least a 10 gallon tank. I have a 3200 lb cabover camper and a towing a 18ft boat (Don't know weight) I eventually want to upgrade the water pump, fan, dual thermostat but this seems to be the quickest and cheapest way for now!

get 2 breathers and plug the Crankase inlet between the filter and turbo, you'll see and feel the difference.

For really really cooling, wrap the WMI inj line around the a\c low pressure return line, which you may have noted is always cold and dripping condensate.


Even more cooler is the a\c receiver\dryer - buncha turns around that sucker could even freeze the WMI fluid. Add a little alchohol?


Inject some 40deg vapor to get those IAT's lower than 120deg.


'Course, this also means higher inj pressure to vaporize the denser liquid, right?


Also, if you were, say, living in Death Valley, or the Sonoran Desert, or some such place, where the ambient is realy hot (140deg) and dry (0% humidity), you might also want to inject some, pre-compressor.


Boost temp is based on intake temp - start lower, result is lower.


:Also - lower IAT by 200deg, lower EGT 200deg.


Result is usually one for one, for same engine loading condition.

Whatnot - why not add a larger water container on the trailer tongue, adjusting the hay load slightly rearward to compensate for added tongue weight, which will vary as water is consumed.?


A 20gal there, plus your 5gal, plus wrapping the linj line around the a\c should conserve quantity required to get the job done.Edited by: gmctd

whatnot, with that 5 gallon tank do you run the injection continuosly or hooked up to a boost switch? Since I have a big truck I figured at least a 10 gallon tank. I have a 3200 lb cabover camper and a towing a 18ft boat (Don't know weight) I eventually want to upgrade the water pump, fan, dual thermostat but this seems to be the quickest and cheapest way for now!





The water comes on at 10-1/2 PSI. While pulling loads of hay, that is about 60% of the time. (because of the corners, hills and stop signs)

Now I have some things to try! TDG I read your post about getting the breathers and plugging the Crankase inlet between the filter and turbo. I will also do this. It may also alleviate the blow by i'm getting out my dipstick. (Seems excessive) I read that the CDR (PVC as I think)could be in backwards causing this.


gmctd, I was gonna ask about injecting pre and post. You have answered that for me! I live in southern Oregon but it gets hot in the summer here! (105 the other day!) I like you idea.Wrapping that injection line is definitely going to happen. I think i'll use some copper pipe for the AC/Dryer wrap that way it will have a better heat/cool transfer than the polypipe i'm using.


I have some time as my truck is down. I replaced the crankshaft sensor and it still stalls. (Thought I had it.) I did the simple test of unplugging the optic sensor and it fired up with it disconnected. So i'm guessing it is bad!(Need to keep the bro's Snap-On scope at my house!) Anyway it is all a mute point. I called the GM dealer in town (Brother use to be one of the head mechanics up there) and talked with the service rep. He ran my vin and said that it was elegible for a IP replacement. I asked him how much for labor or whatever and he said nothing!(Pays to know people!) The truck is going in on the ninth so I'm just doodling with what I can in the mean time. I have found some interesting things on the PMD though but I am waiting on a email back from the transistor manufacture.Then I'll post what I know so far if it pans out to be true.Edited by: mdhorban

I have been running it with the water tubing around the AC. I was thinking about using copper and insulating it but was afraid that it would freeze up.


http://www.dieselplace.com/forum/uploads/129_wmi.jpg

whatnot


Why not put some heat transfer compound between your tubing and the receiver and then wrapping the whole thing in insulation to block off the engine temperatures which are now effecting 80% of the tubing as it is wrapped around the receiver. Also insulate the tubing from the receiver to the injection point. If your water tank is mounted under the truck I suspect the water temperature is close to 140+ degrees after a few miles as this is the temperature flowing back from the engine on an average summer day.


As for fear of freeezing the water. If your AC is fully charged the suction pressure as seen on a guage will not drop below the freezing point and if the AC is on with the fan on you will have some Super Heat in the receiver anyway.

If it freezes just turn the A/C off for a minuite.
Copper would work well and if you soder you could put fittings for the vinyl tubeing, wrap it up as a unit.

I wouldn't worry too much about freezing up that water line. It would take an enormous amount of time to freeze that water in the line. It takes a lot of latent heat removal from that water to get it to freeze. It would turn slushy first before freezing hard too, by that time, it should have moved down the line.

Lets back up a minuit. Where is the vaporation of the water taking place? Are we assuming the air temperature coming off the compressor is above 300 degrees F


If you want to vaporize the water before it enters the cylinders you do not want to cool the water but may want to heat it to insure the laten heat of evaporation takes place in the air flow before it enters the cylinders. This would decrease the density of the air and increase the total air charge entering the cylinder.


If you cool the water vaporization may not be complete before the charge enters the cylinder and you may end up with water droplets entering the cylinders, thus producing stean in the cylinders but not having increased the total air charge as much.


Who has taken a Thermo class lately and which produces more power?Edited by: HowieE

Plastic is a fair insulator, so wrapping insulation around the plastic WMI tubing and dryer cannister would cool the water better, plus the plastic line would transfer less engine compartment heat to the fluid from there to the point of injection.


Plastic tubing would also prevent water freeze-up in the line - I'm sure you've all seen the dryer iced up after a long drive, and at ~15mpg water injected, we're not talking a large amount of flow thru that line.


Good idea, whatnot - lookin' good!


Should require less cool water injection to remove same amount of heat than hot water, right?


Further scientific discussion requested (required?) on this point......


And, of course, the compressor outlet temp is not always 300deg, tho the 10.5psi Boost whatnot runs loaded would keep it up there. I was seeing 220deg up steep hills with only 7.5psi Boost, where it had time to cool on the down side, then right back up to 220 on the next.Edited by: gmctd

Why not do the fuel line the same with copper tubing.

Would certainly keep the inj pump and PMD cooler, wouldn't it?


Now, if we could find some way to control soaring shut-down temps.....


HowieE - the vaporization/misting takes place across the injection nozzle.Edited by: gmctd

Actually, the water makes a huge difference in the temperature after shutdown. Since the intake manifold isn't hot, it can absorb a lot of heat. I hadn't really thought about it before but I think it was a lot cooler under the hood after shutdown. I will have to check it out tomorrow.


Also, the water can lower the EGT more than the amount it lowers the IAT because since it makes more power with it on, less fuel in injected to make the same power with less heat. (can be 300 - 400 degrees lower under certain conditions)

One thought about the fuel line going around the a/c accumulator: in the summer time, (I'm not sure about the fine science behind this) would you run the risk of cooling the fuel to the point of waxing/gelling if not careful. Most summertime fuel is not set up for cold temperatures, I wonder between cooling ablity, flow rate, incoming fuel temperature, if you may be approaching that possibilty of gelling, or if it would be so remote, that it would not matter.

Good points - Diesel Power Services offers several additives to compensate.


PCM may react adversely to cold fuel temps.


Still, would be good to reduce pump fuel temps to below 100deg, for PMD longevity

Diesel fuel doesn't wax until somewhere in the -30 range, shouldn't pose a problem. I would like to see if you could take a scanner and read difference in fuel temps a/c on vs off.

As engine coolant temps rise, fuel temp rises.


At ~180deg ECT, fuel temp is ~127-130deg.


At 205-210 deg, a-c on, fuel temp is 140deg, rising some as tank level drops to 1/4.


Have not seen it much higher than that, except after shut-down heat-soak, and it quickly cools back down at Start.


Switch to the full tank, and it drops to ~135-137deg at 200deg ECT.Edited by: gmctd

What would be wrong with a 'swamp cooler' style WMI? What if you could put in a small section of swamp cooler matting, held in place by chicken wire and supply it with water from the jet? If water quantitys were well managed, you could ensure that only evaporated water enters the turbo/engine, and you could cool IATs by evaporation the way a swamp cooler does. Edited by: Texas Diesel Guy

Those coolers operate at minimal static pressure increase from Baro, measured in inches of water.


27" h2o is only 1psi.


Pressure and flow rate are limited to prevent the water from blowing right out of the mat.


If mat were dense enough to retain the water, little flow-thru would be possible.

fine, put a full squirrel fan swamp cooler in the bed and plumb a snorkel into the airbox to feed the engine LOL


I really don't see how any of there WMI systems can make any resonable difference, especially considering the hassle, but if someone has put in a system and can post proof, I'd very much like to see it.

What kind of proof are you looking for? I can watch the MAT drop from 220 to 130 within seconds after flipping the switch and the coolant temperature drop 5 to 10 degrees while going up a hill.


It probably works better on some trucks. Also, a truck with stock boost setting will probably not make near as much difference.


I peak at 15.8 the way it is setup now and the WMI can hold the IAT / MAT down near 130 degrees at that pressure.


It would take a dyno to prove if there is a difference in power, but even if there isn't, it keeps the temperatures down so the computer doesn't have to cut back fuel.

Inlet air temp is of little concern, here - reduce inlet air temp by 10deg, reduce Boost temp by 10 deg.


Where inllet air temp is 100deg, 10deg cooler is a big change.


Boost temp out of the compressor is 300deg - reduce that to 290deg does not make any difference in 6.5 output.


Inject some 120deg water vapor - water is much denser than air - and reduce that 300deg Boost temp to 120deg.


That temperature reduction results in a significant increase in power output.


Normal Boost temps run around 180deg at 4-5psi - reduce that to 100deg or so, the engine will return quicker response with lower overall operating temp.


Similar to running on a cool morning, as opposed to running in hot noontime traffic.


.As whatnot indicates, light trucks do not respond as much, with lower overall Boost pressures, but the advantages are significant for a heavy workhorse.


An air-over charge-air (Boost) cooler does the same thing, at only a 1000 dollars more, give or take.....


And, no thanks, on that swamp cooler in the bed idea - wouldn't mind dual stainless exhaust stacks, tho, with them little flappers on the tops.....

Has anyone combined a watermist in the exhaust with a charge air on the intake?
I would think you could cool things both ways.

What would the watermist in the exhaust do?

I could see the watermist after it is vaporized from combustion increasing exhaust volume and giving the turbo a little more kick. I don't see any negative side effects, H2O is normally present in exhaust anyway.