As a frequent lurker, and closet WRX fan, I thought I would steer you guys to a thread I posted recently on the MR2 board about water injection. As many of you already know, Subaru has been using this technology on their WRC cars for some time now due to the extreme heat these motors develop.

Thanks to a client I now represent here in the U.S., ERL/Aquamist, this technology has trickled down from WRC rally to forced induction street performance.

While I have seen discussion lately of intercooler water sprayers, and rumor has it that the new STI will feature same, I thought some of you here might find the information useful as well:

Click Here

Also, feel free to contact me directly with any questions.

-- DavidV

 

Good information, though its important people understand water injection and water sprayer are two completely different mechanisms.



SLR-

 

Good point, SLR. I should point out that Subaru has been using both on the WRX. The've uses a simple water sprayer on the STI (which merely sprays water on the surface of the air/air intercooler to cool it down) and water injection on their WRC cars (water is injected into the intercooler piping right before the throttle body to dramatically cool the intake charge).

Ford also offered Aquamist water injection as an OEM factory part on its homologation version of the Ford Escort Cosworth in Europe.

-- DavidV

 

I've got a friend who uses the setup on his GN. Hell I've even heard of variable propane injection on some drag cars.

 

You supply your own tank (everything else is included). Many users prefer to tap into their windshield washer reservoirs. This has several advantages. It takes up less space in the engine bay, there is already a low water level indicator light in the dash, and since the Aquamist system does fine running on windshield washer detergent and water mix, this reduces the risk of having the water in the tank freeze in cold temperatures.

Personally, I run a Summit Racing fuel cell as my water reservoir.

-- DavidV

 

Sadly all of that is true for the 3SGTE motor. Toyota's factory ignition maps are far too aggressive for anything over 15 psi and the stock IC is prone to heatsoaking, contributing to making a bad situation worse.

You'll notice that in 12 pages of discussion on the MR2 board, no one has really disputed these claims. Unfortunately, those of us in the MR2 community know far too many fellow MR2 owners, as well as third Gen RX-7 owners, who have already lost motors to heat induced detonation. Call it a scare tactic, but I would hate to see boost happy WRX guys suffer the same fate.

-- DavidV

 

I don't have any EGT data on my own car. However, I grabbed these testimonials online and I'm sure there are others as well:

Syclone

"The most significant aspect of the 40°C EGT reduction is as evidence of how water is affecting the peak combustion chamber temperatures, thus suppressing the onset of detonation. The temperature reduction is significant and permits increased boost... timing... power. Such a reduction can, for instance, mean the difference between piston crown meltdown... or not."

http://www.syclone.freeserve.co.uk/waterinjection.htm

Dinan SC M3

"I have a '99 M3 with a Dinan SC kit, which Ive boosted to 11 psi, with the only charge air cooling in use provided by your kit. Everything was very good throughout the cooler months, but I was really waiting to see what happened on those 90 degree plus days...

Today is such a day up here....I just took a few hard runs to rev limiter, and Im very pleased to say that my EGT values never exceeded 1200 degrees! As a matter of fact, I register a higher temp when driving at say 4500 rpm cruise, when no water is spraying, ie, when Im hardly making boost....When Im heavy into the boost, like over 4 psi, and the water is spraying, the temps are fine... "

http://www.activeautowerke.com/Wate...testimonial.asp

MKIV Supra TT

"However, under extreme conditions such as very high ambients of 25 deg C or more and under full power for extended periods, exhaust gas temperature can rise above the 900~950 degC threshold. The most I have seen without water injection is 1050, and whilst no problems were reported it would be unwise to continue running the vehicle at this excessive limit, even at the very short time periods involved. With water, the most I have ever seen is 900 degC."

Anyone else?

-- DavidV

 

[please delete: double post]

 

Good questions, AntiochCali.

Depends how you have your water injections set up. Is it an Aquamist system 1S or comparable that comes on every time you hit boost? Is so, you'll go through a bit more water. If its something like a system 2C or 2S that you have mapped, you will go through quite a bit less. Other variables include how you drive the car and nozzle size.

Using a system 2S on my MR2, I top off my reservoir every 3-4 weeks for street driving. So maybe every third fill-up or so?

Yes, on the System 1S, this is done through nozzle sizing (bigger nozzle = more water, smaller = less). On the systems 2C and 2S you can remap the water delivery as needed through either a standalone ECU (2C) or handheld controller (2S).

I have yet to see one of ours fail. The pumps supplied with the Aquamist kits are the same ones used in WRC applications.

For best results, I recommend injecting it right before the throttle body. This ensures that you get the full benefit of in-cylinder cooling.

Feel free to contact me and I can either put you in touch with one of our dealers, or help you myself. Since I am local (NorCal) you can even stop by and check out the systems if you like.

(415) 509-2409
AIM: BoostedGroup
Email: info@boostedgroup.com

-- DavidV