Building a Budget Water Injection System
 

Well I was heavily recommended by my tuner to look into water injection before going to the track. I'm running a stock S5 top mount intercooler, and as you can imagine, air temps skyrocketed after one dyno pull with the hybrid turbo I have.

I'll start by breaking down the turbo system a bit.

- S5 Turbo, with a U-Trim Compressor Wheel, TA-34 Turbine, T04B .60 AR Compressor Housing
- Stock Wastegate at 5psi, but creeps to 9-10 psi by about 4500(?) and tapers off to 8-9psi
- CorckSport Turbo Inlet Pipe with Filter located in a nice cool place
- Stock Turbo Outlet Pipe w/ a Synapse BOV
- S5 Top Mount Intercooler

All on a Stock S4 Block.

I'm kind of on a budget with this build, but I will not compromise on the quality or effectiveness of the parts I've installed. However being that it's only water injection, I will definitely use more China/eBay parts on this system than I have with some of my previous upgrades. If I was doing water/meth where A/F ratios needed to be tuned then I'd probably get the AEM kit no doubt.

Luckily my EMS-4 has an I/C spray feature, and since water injection doesn't have to be pulse width modulated with a high current controller, the ECU should handle this fine w/ a standard 30/40A relay.

So here are the parts I'm looking into for the W/I system:

SHURflo On-Demand 1GPM, 60psi, 12v Pump: SHURflo On-Demand Diaphragm Pump — 1 GPM, 60 PSI, 12 Volt, Model# 8009-541-236 | Sprayer Pumps| Northern Tool + Equipment

Alcohol Injection Systems 5GPH Water Injection Nozzle: The Best Water injection system and water methanol injection systems at AlcoholInjectionSystems.com
(can be found on eBay for about $32 shipped)

12v Water Solenoid Valve w/ 1/4" Push Connect Fittings: http://www.ebay.com/itm/1-4-Solenoid-Valve-Aluminum-Air-Water-Gas-12v-Volt-DC-w-Push-connect-fittings-/111309182833?pt=LH_DefaultDomain_0&hash=item19ea8b5771($17 shipped, can't go wrong with that)

I will also need some misc. fittings obviously, but I just wanted to point out the main components I'm looking into.

The water tank I'm still up in the air for. I may be able to find a cheap, vented, durable plastic tank at some local store for gardening or farming, but if I can't then I'll probably go with the 1 gallon tank from CollingMist.com:

1 Gallon Water/Alcohol Tank

That's it for now, I'm hoping I can start ordering parts in sometime this month and post up on this for any people who may want to look into a similar solution in the future.

Doesn't the zone sell those aftermarket/stock/ish washer fluid reservoirs? I think the largest one holds about a gallon? I can't wait to come down and see your car now that it's tuned.

You didn't specify, but since this is a budget system and water only, I'm assuming it will be boost activated. FWIW, I'd recommend a float sensor in whatever tank you choose to activate a small red LED as a low level warning. I also hooked up a green LED to light up when the pump is activated. Not sure how else you'd set the boost level for pump activation without one. Both LED's I sourced from the local Radio Shack...cheap. Both are decently bright. Anywhere near your line of vision and they should be bright enough for track duty even on a sunny day. The float sensor I got from Devil's Own, but other suppliers have them.

It'll be activated by my EMS, I'll be using the intercooler spray feature to kick the relay/system on. I'll have an interceptor switch to the 12v wire going to the relay, it'll be my on/off switch.

I don't want to get to fancy with it so I doubt I'll get a float level sensor, even though I've seen some for like $3 on eBay. I wont be using the water injection system to make more power, but mainly to keep charge temps down and keep everything reliable.

I found 2 tanks that may fit the dimensions I need, though I will probably get the pump and plumbing first to have an idea how much space I have. My goal is to fit everything in the rear driver side bin area. It may be difficult but if I can get it done it'll be worth it I'm sure.

Here are the two tanks I'm considering:

1 Gallon Natural Tank 11.25"L X 6.5"W X 4.5"H (1-3/4" Neck) 12777: http://www.usplastic.com/catalog/fil...ings/12777.pdf

2.5 Gallon Black Tank 12.75"L X 7.75"W X 7.75"H (2-1/4" Neck) 12778: http://www.usplastic.com/catalog/fil...ings/12778.PDF

Can be found here and are real cheap at about $13 and $18 respectively: Multi Purpose Tanks | U.S. Plastic Corp.

I'll be looking to order up the pump and plumbing stuff pretty soon, and will post pics once I get some stuff mounted.

Oooo, definitely going to be buying some of those nozzles. I want to put direct to manifold water injection on my Audi 5-pot and one issue these engines have is horrible wet flow in the intake manifold. So the idea is five much smaller nozzles mounted one-per-runner. It won't give the many and various charge cooling benefits but you get the anti detonation benefits which is really all I'm after.

Got everything installed, here's some pics that'll do the talking:

https://www.rx7club.com/attachment.p...1&d=1401997660
All I did for the nozzle was cut off the little elbow that is normally in this location and drilled and tapped it with a 1/8" NPT Tap. Pretty good location I think and should mix in with the incoming air real well.

https://www.rx7club.com/attachment.p...1&d=1401997660
Here's how it looks installed and you can kinda see the solenoid that I mounted on the passenger side strut tower.

https://www.rx7club.com/attachment.p...1&d=1401997660
Finally here's a pic of the 2.5 Gallon Tanks. Fits perfect and I used some rope to tie it down, hopefully it wont rip but the reason I used it is in case I ever need to remove the tank quickly. The pump I mounted right on that rear panel with some self tapping screws. Had to make sure I drilled in the right spot though, since there are some brake lines mounted back there.

Here is a quick snap of the data log showing how the air temps dropped. I was only free revving the engine, so more testing needs to be done under boost.

https://www.rx7club.com/attachment.p...1&d=1401998375
Here we are 104 degrees Fahrenheit.

https://www.rx7club.com/attachment.p...1&d=1401998375
And here we are 93 degrees Fahrenheit.

Thread update!
 

Got a chance to run the car at the track, ended up going to the Balcony in Willow Springs. My current injection settings have the system kick on when it's above 5lbs of boost and 84* AIT.

Overall, intake air temps were good. While idling or sitting, temps were 135-145* Fahrenheit, which seems normal considering it was 105* out. What does worry me though is that the air temp would stay way low even after the water shuts off...

I'm almost thinking that the water may condense on the temp sensor which gives basically faulty/inaccurate readings. If someone could shed some light on this it'd be greatly appreciated. In any case, here are some shots of my data logs:

Running down the straight before water injection kicked in:
https://www.rx7club.com/attachment.p...1&d=1404958634

Air temps while in drift [clutch kicking, WOT to Decel, crazy s**t]:
https://www.rx7club.com/attachment.p...1&d=1404958634

Air temps while cruising after the drift run. These are the temps that concern me the most, especially considering I have the nozzle post intercooler, so it's not like the tube and fins from the core were necessarily cooled down.
https://www.rx7club.com/attachment.p...1&d=1404958634

I would think that the amount of water condensation that could possibly build up would be moved away very quickly by the 100+ degree air.

However, better to have it stay richer longer than vise versa.

Yea it just really doesn't make sense to me. The only thing I can think is if there's a little bit of condensed water on the end tank of the intercooler and even if the water isn't being injected it will kinda jump into the air stream and keep the temps cool.

But yea, it does run it a bit richer this way so it should be safe. Just need to make sure my ignition doesn't advance at these temps.