Cheap Water Injection - PeachParts Mercedes-Benz Forum

pdrayton · #1 02-19-2012, 02:26 PM

Here's a few pics on how to make a cheap water injection for your mercedes diesel. AKA 'turning stuff you don't need into stuff you do need'.

Water injection is a fairly well accepted method of cooling the air charge, and cleaning internal engine parts. I've been running WVO and losing a bit of compression and power, so I decided to put in a Water Injection (WI) system.

Not having a lot of money for car stuff, I hodge podged a few things together.

See the pictures attached.

1. The heart of the beast - the pressure switch. It's best to inject the water when the engine is under load. So you put a pressure switch to switch the water pump on at about 10psi boost. I made a cheap pressure switch by attaching a push button switch to the top of a compressor pressure release valve that I had replaced the spring in so it opens at about 8 psi. T-d off the boost pressure gauge to supply boost pressure to the switch, and bada bing bada boom, it switches on when boost goes above about 8psi. As second safety check against spraying water in to a idling or off engine, I connected the power to the switch to an ignition on fuse in the fuse box (fuse 7)

The current from the switch goes to a relay.
2. Relay and water filter. The water comes from the windshield tank. I don't have any space under the hood, what with my WVO conversion stuff in there.

3. pump. I 'stole' this pump from the RV out back. It's stationary and not going to the camp ground, so it doesn't need the water pump. It's only a 45 psi pump, which is at the bottom of the range of what you want to inject at. Rule of thumb I heard is you need a pump with at least 2x the boost pressure.

The connections for the water on it are the only 1/2" to barb I could find at Lowes. I'm still looking for a better 1/2" to barb.....

4. Pump to intake. I tapped a 1/8 npt hole in the crossover pipe and used thread lock to screw a mister nozzle (Mcmaster part# 3178K75) into the crossover pipe, and then attached an adapter and 90Deg fitting to fuel line. It's a low pressure system, so it's not critical parts. Some of the good systems use 200PSI to really atomize the water, but alas, did I mention this is a cheap system?

Voila! there is it. Works as advertised - while driving it switches on at about 9psi. We'll see what it does for my compression and power.....

Please refrain from "colorful metaphors"

1992 300D 240K

oldsinner111 · #2 02-19-2012, 02:31 PM

Good job I have a 50psi pump

destroy · #3 02-19-2012, 03:05 PM

i've been thinking about doing one of these for a while.

the only question i really have is could the mix be injected into the elbow of an intake after the air filter or should it be going into the manifold?

Renntag · #4 02-19-2012, 03:44 PM

Great thread.

2 things I'd like to mention. I use Water Injection on a 6.5 TD to intercool the air charge for better towing performance.

I used a 90* pipe fitting at the intake inlet, not a mister nozzle. Imagine dumping the contents of a bottle of water out the window at 50mph. It atomizes instantly. The column of air entering the intake is hot and moving fast, enough to turn the water into vapour.

I also used a small ball valve to throttle down the water flow from the pump, testing it by measuring volume to time. I did so by seeing how long it takes to fill to 8 ounces in a clear container. Looking for 32oz/minute, it should take 15 seconds. This wasnt a perfect test as my container wasnt under 10-15psi pressure, with a relief valve to allow air out.

To control the system, I used a Hobbs switch threaded into an 1/8" npt hole I drilled/tapped into the intake. Watching a boost gauge, I drove the burb to make boost and watched at what point the switch activated a light. I adjusted the switch until the correct pressure trigger was achieved.

Two keys necessary for this project on any vehicle are boost and pyrometer gauges. They dont need to be permanently installed, but are needed to calibrate the system. Seeing that the system engages at the proper pressure, and EGTs (Exhaust Gas Temps) drop by 3-400*F will prove that its working. At that point, the gauges can be removed, but some may prefer to keep an eye on boost and EGT.

If anyone has access to a very small inspection camera, perhaps they might wish to look inside one of these OM diesels before and after water injection to measure effectiveness of steam cleaning benefit without tear down.

Maybe testing two motors, one with EGR eliminated, one with out.

Renntag · #5 02-19-2012, 03:53 PM

Quote:

Originally Posted by destroy

could the mix be injected into the elbow of an intake after the air filter or should it be going into the manifold?

Assuming I understand you correctly, you are suggesting injection before the turbo? I would say it is possible, but the water must be ultra fine mist so as not to pit the impellers of the turbo compressor.

From what I have read on this subject, it is easiest to inject just after the turbo. This also can be done just as a stream of water, no nozzle needed. A nozzle isnt a bad idea, just not needed over 8psi.

A gentleman by name of "KillerBee" has made a water injection "Cuff" for preturbo injection. It ultra mists water at very high pressure to cool the intake charge prior to the turbo also taking heat away from the turbo compressor housing itself. This is a more expensive option, but very effective if that fits your budget. Note that this thread is focused on being cheap.

Have a great day all !

pawoSD · #6 02-19-2012, 04:44 PM

So what happens to the water container and hoses/pump etc when the car sits overnight in 5F weather?

BoiseBenz · #7 02-19-2012, 04:47 PM

Very hillbilly.

I love it!

engatwork · #8 02-19-2012, 07:42 PM

A system from this company was showcased on one of the automobile shows this past weekend. Looks like a pretty neat set up. Seems that the water/methanol injection is the route to go.

Snow Performance

ROLLGUY · #9 02-19-2012, 08:04 PM

Nice way to do it "on the cheap". I am not sure if I saw a check valve, but you probably need one. I am trying to do a system cheap as well, but I have a few more challenges than you. I have been trying to find a good way to WI a 617 for a while now. The problem is that there is not a good place to put a nozzle in a 617 because of the short distance from the turbo to intake ports. The turbo outlet points right at cyl #1, so that cyl would get a greater volume of non-atomized water.
The OP (pdrayton) does not have that problem because he has a 2.5 which has the crossover tube and long intake runners. I had a brainstorm the other day, and figured out the perfect solution (I think). Most 617 owners delete their EGR, which leaves the port available for a water injection nozzle. However, the problem stated above still applies. The solution I thought of might just work. I will try to explain it, as I have no way to illustrate it otherwise. If I was to make an injector that curves around into the center of the turbo outlet (mounted on a plate bolted to the EGR inlet), spraying water directly against the air flow, that should atomize the water properly. I have a non-EGR manifold on my car now, so I got an EGR manifold out of my shed to get cleaned up for some experimentation. I have all the rest of the components of a Coolingmist (brand) system- pump, nozzle, hoses, boost switch, etc. I found the entire kit (less the tank) for $120.00 on the 'list. I will probably use the windshield washer tank as well.

destroy · #10 02-19-2012, 08:06 PM

Quote:

Originally Posted by Renntag

Assuming I understand you correctly, you are suggesting injection before the turbo? I would say it is possible, but the water must be ultra fine mist so as not to pit the impellers of the turbo compressor.

From what I have read on this subject, it is easiest to inject just after the turbo. This also can be done just as a stream of water, no nozzle needed. A nozzle isnt a bad idea, just not needed over 8psi.

A gentleman by name of "KillerBee" has made a water injection "Cuff" for preturbo injection. It ultra mists water at very high pressure to cool the intake charge prior to the turbo also taking heat away from the turbo compressor housing itself. This is a more expensive option, but very effective if that fits your budget. Note that this thread is focused on being cheap.

Have a great day all !

Yeah, that's kinda what I figured. Never hurts to ask! Cheap is good, but sometimes it's nice to pay a little for something that works and looks nice. I've looked at a few kits from Snow for my Benz and my bus. I'll probably go that route when I do.

Quote:

Originally Posted by pawoSD

So what happens to the water container and hoses/pump etc when the car sits overnight in 5F weather?

Since the water-meth is basically an alcohol and loosely related to your -30* etc winter washer fluid, it should stay liquid... driving would certainly warm it up enough sooner or later with under-hood temps raising, pending some 0* Kelvin temperatures...

pdrayton · #11 02-19-2012, 10:34 PM

There are 7psi air pressure switches like this Airtex OS75 for $13. It switches on at 7psi, not adjustable.

One thing I will change on my setup is to get the mister from summit or coolingmist that has the thread on the outside of the nozzle so it can't fall into your intake.

Also, I'm not sure about the water being atomized if you don't spray it at high pressure. I had a leak in mine and there was water coming out of the tube leading to the pressure switch.

bmwpowere36m3 · #12 02-20-2012, 01:37 AM

45 psi or so I a little low to fully atomize the water/meth. I would say 100 psi minimum, closer to 150.

pdrayton · #13 02-20-2012, 09:21 PM

Yes, 45 psi is low. Did I mention I got the pump for free and I don't have $125 spare for a 100psi pump?

Regarding the check valve - I didn't put one in because I saw that my pumps successor has a built in check valve, and I don't see any return air when the pump is off, so I assume it has a check valve. I also have a suspicion that since it is a diaphragm pump, it is naturally a check valve.

destroy · #14 02-22-2012, 08:45 PM

Quote:

Originally Posted by ROLLGUY

Nice way to do it "on the cheap". I am not sure if I saw a check valve, but you probably need one. I am trying to do a system cheap as well, but I have a few more challenges than you. I have been trying to find a good way to WI a 617 for a while now. The problem is that there is not a good place to put a nozzle in a 617 because of the short distance from the turbo to intake ports. The turbo outlet points right at cyl #1, so that cyl would get a greater volume of non-atomized water.
The OP (pdrayton) does not have that problem because he has a 2.5 which has the crossover tube and long intake runners. I had a brainstorm the other day, and figured out the perfect solution (I think). Most 617 owners delete their EGR, which leaves the port available for a water injection nozzle. However, the problem stated above still applies. The solution I thought of might just work. I will try to explain it, as I have no way to illustrate it otherwise. If I was to make an injector that curves around into the center of the turbo outlet (mounted on a plate bolted to the EGR inlet), spraying water directly against the air flow, that should atomize the water properly. I have a non-EGR manifold on my car now, so I got an EGR manifold out of my shed to get cleaned up for some experimentation. I have all the rest of the components of a Coolingmist (brand) system- pump, nozzle, hoses, boost switch, etc. I found the entire kit (less the tank) for $120.00 on the 'list. I will probably use the windshield washer tank as well.

My knowledge on this is probably pretty limited compared to plenty on here, but since I'm not looking at the manifold... let me get this straight: the inlet from the turbo points directly into the intake for the #1 cylinder?

Without some kind of crossover where would be better? The middle? Multiple points? Would it really matter all that much? Like, is this really that big of a deal? Logically if there was so much more pressure present, wouldn't there be an even larger discrepancy than usual between #1 and the other cylinders due to the differences in intake and the resulting combustion/cylinder pressure from the turbo?

ROLLGUY · #15 02-23-2012, 12:01 AM

Quote:

Originally Posted by destroy

. let me get this straight: the inlet from the turbo points directly into the intake for the #1 cylinder?

Take a look at the OM617 in both of your cars and you will see what I mean.
I think I have it worked out, I just need to wait for my buddy to bring back my extra manifold that he is hot tanking for me.