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PseudoSport HalfDork
8/17/12 11:41 a.m.

I’ve been reading up on water injection and was thinking about putting together a system for our Challenge Jeep. The vehicle is already running off MegaSquirt so controlling a pump should be pretty easy. Now I’ve read up on people using a high speed solenoid and injecting the water with the same pulse as the injectors. I’ve also read about people triggering only the pump and having a check valve. If I can avoid buying a solenoid that would be great unless I really need one. How would you set it up?

I’m also trying to find a cheap pump. I don’t think windshield washer pumps are going to put out enough pressure since I need a minimum of 40 psi. Do you think a marine water pump from Harbor freight would be enough? What else could I use?


petegossett UltraDork
8/17/12 11:49 a.m.

15-years ago I remember finding a DSM home-built unit online that used an aquarium pump or something silly. I don't remember details, but seems like it was ~$100 or less in all new parts.

Knurled SuperDork
8/17/12 11:54 a.m.

Boost pressure and inject it pre-turbo?

1988RedT2 UltraDork
8/17/12 11:54 a.m.

I run a coolingmist unit on the RX-7. You can peruse their website for info. Snow is another one.



4cylndrfury UltimaDork
8/17/12 12:09 p.m.

a small 12v air compressor and a SS tank full of water...pressurize the tank with the pump on a pressure switch, and use an injector triggered by megasquirt to spray into the intake tract...tank is always "hot" with pressure, Megaqsquirt+injector determines when to spray. Since the spray will be low volume, the compressor wont have to run too often to keep the tank up to pressure .

$26 at Harbor Freight

weedburner New Reader
8/18/12 9:58 a.m.

or use a small co2 tank/regulator for serious pressures...

fifty Reader
8/18/12 11:50 a.m.

Here's how I did my Megasquirt water injection back in the dizzay:

  1. Bilge pump from Walmart ($19.99)
  2. Spray nozzle, solenoid, brass tees, hose and other crap from McMaster Carr.
  3. Washer fluid reservoir from a Cadillac - I used this since it has a low fluid sensor integrated into the reservoir.
  4. Windshield washer fluid for injection - it's 50/50 Methanol / Water which enhances the cooling effect.

I based the build on an old Mitsu Mirage turbo write up - here is the writeup with part #s http://www.turbomirage.com/water-alcohol-injection-parts-list.html

I modified their setup - my pump ran continuously (to maintain system pressure) and the ground pin of the solenoid was wired to the Megasquirt .

I've since gone to E85 - same cooling with less complexity, and less potential for failure. WIth E85 you need ~ 30% more flow from the injectors. I went to larger injectors and a beefier fuel pump ($90 from Summit), but you could easily increase fuel pressure at the fuel rail by 30% and get the same outcome. Some people crush the FPR cans to get more pressure, or you could go with an adjustable FPR from ebay.

I salute your innovation!

m4ff3w UltraDork
8/18/12 12:37 p.m.

How long would an injector last spraying water?

What about a small self contained fuel system spraying E85 instead? Or would it just be way too rich at the point you get enough cooling?

donalson PowerDork
8/18/12 12:58 p.m.
m4ff3w wrote: How long would an injector last spraying water? What about a small self contained fuel system spraying E85 instead? Or would it just be way too rich at the point you get enough cooling?

Not long based on when I asked some years back...

I considered a tolune injection system back before e85 was ago.... Build a 2nd fuel system with injectors upstream of the throttle body

As for inexpensive water/ally injection I've known some to do it with 2 windsheild pumps in series and the tank gwen a hose

donalson PowerDork
8/18/12 1:02 p.m.

Er stupid phone

Anyway... Used a hose to the intake to add pressure under boost... I'll dig up the thread when I get home...

Zomby Woof
Zomby Woof UltraDork
8/18/12 1:39 p.m.

You can find SS injectors, and SS fuel pumps in the wreckers these days.

I ran a Firefly turbo (Swift GT) fuel pump, and injector in a water/alcohol injection system for over a year without any problems. I used windshield washer antifreeze, and cycled the injector off a home made extra injector controller board.

iceracer UltraDork
8/18/12 6:12 p.m.

I just read an interesting article in Air &Space Magazine. Part of it was about water injection on the air racers reciprocating engines. Too much reduces power. It takes a very small amount to do what it is intended for, to inhibit detonation. They use a 50/50 mixture of water and methanol.

iceracer UltraDork
8/18/12 6:41 p.m.

Found This: They were using a No. 20 drill size jet/ .161" Of course that is feeding 3450 cu.inches. So it would have to be really small fo an auto engine.

donalson PowerDork
8/18/12 6:52 p.m.

here the thread is on turbobricks... it's super GRM ghetto fabulous http://www.turbobricks.org/forums/showthread.php?s=c322dad1125135d39e0e6b6aef84c151&t=10208

noddaz Reader
8/19/12 8:39 a.m.

From an old article in Hot Rod I remember something about a Hobbs switch being necessary... (But I don't remember why...)

donalson PowerDork
8/19/12 1:29 p.m.

hobbs switch is an adjustable pressure switch so it'll come ON at a certain pressure...

to Zomby Woof... what did you pull the SS injector/pump from?

PseudoSport HalfDork
8/19/12 10:23 p.m.

Since I'm running megasquirt I won't need the hobbs switch. I can program it to come on at any pressure I want.

We are not running E85 since we would have to budget for larger injectors and a pump. Also the closest startion that has it is 35 miles away.

chaparral HalfDork
8/19/12 11:08 p.m.

Windshield washer tank and pump, with a calibrated restriction into the line before the turbocharger.

donalson PowerDork
8/20/12 12:20 a.m.

beware... I hear that you'll see some rough compressor blades in fairly short order if you do it before the turbo...

donalson PowerDork
8/20/12 12:23 a.m.

er also this is a better write up on the ghetto windsheild washer pump style alky/water injection


Nashco UltraDork
8/20/12 12:41 a.m.

FYI, I ran E85 in the $2011 N600 and we were able to easily get E85 in town. Might be worth seeing what you can get away with on E85 with the hardware you've got before pouring water in the fire. Quite possible that you don't run out of injector depending on how much pressure your fuel pump can put out at max power.


PseudoSport HalfDork
8/20/12 9:52 a.m.

Our fuel system is just about maxed out. We are running GM 32 lbs injectors and have the regulator crushed so they flow more like 36 lbs. That should be enough to safely make power we want to. Our current problem is intake temp. Last time we were not running an intercooler and had temps over 200 degrees. It’s also a non cross flow head so the turbo sits right under the intake manifold which doesn’t help. We only have room for a small intercooler so I was looking into water injection to cool things down.

The jeep does have dual washer pumps so maybe I’ll measure the pressure those put out.

mrwillie HalfDork
8/20/12 2:06 p.m.

Not to threadjack, but could a water injection setup be used in a NA engine to lower its octane requirements? I'm not understanding the info that I've found on the subject so far. It seems that it should work( by decreasing the engine's tendency to detenate while running a lower octane fuel ), but maybe I'm not understanding the physics.

alfadriver PowerDork
8/20/12 2:40 p.m.
PseudoSport wrote: Our fuel system is just about maxed out. We are running GM 32 lbs injectors and have the regulator crushed so they flow more like 36 lbs. That should be enough to safely make power we want to.

Can you take a picture of the tip of one of your injectors?

If you have a spare, you might be able to cut the tip off, which will almost double hte flow out of the injectors. It just depends on the injector design.

(assuming that E85 is a realistic idea)

PseudoSport HalfDork
8/20/12 3:41 p.m.

Injectors are slim Bosch ones, have 4 holes in the tip, and look a lot like these:

Our fuel pump is rated for around 160 LPH which will be the next weakest link in the fuel system.

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