Update (08/13/2003) - Joe's Water Injection Kit
Update (04/15/2003) - Water Injection Controller.
Update (12/31/2002) - new images and videos
Here are some images of the mcmaster car nozzles mounted inside the throttle body.
An overview video of the water injection setup is here (WMV
format 8MB) - it's a little nerdy - but all in good fun!
Video of each of the nozzles spraying inside the throttle body is here (WMV
format 4.7MB - MPG format
19.6MB) and another of both spraying is here (WMV
format 1.5MB - MPG format
6MPG). In the first video one can here the Shurflow pump turn on for
a few seconds to re-pressurize the accumulator at two points during the video.
Update (12/16/2002) - new Nozzle size.
I've switched the two mcmaster car
nozzles from a 3GPH and 5GPH, to a 5GPH and 10GPH for a total 15GPH or
946cc/min. This is not the actual flow, however, since I'm running
almost 20psi of boost, and the water pressure fluctuates between 70 and
100psi. So at 70psi of water pressure, and 20psi of boost, the
actual pressure is 50psi. The shurflow pump is adjustable, and
I want to try to change it so that it will turn off at 100psi like it
already does, but come back on at around 85-90psi.
Using the formula 
where
F represents flow and P represents pressure, one can calculate the flow difference. In
this case the nozzles should flow 15GPH at 100psi, so at 50psi, the actual
flow is 10.6GPH or 668.75cc/min. At 80psi the actual flow is13.4GPH or
845cc/min. So, with the current setup the water flow can range from 30.4%
of fuel flow to 38.4% fuel flow, assuming the 550cc/min injectors are static
open.
The 3SGTE runs great with this setup - nice and smooth. The previous
day (about 40degrees outside) I was doing some tests and the ECU went into
the bad gas mode (see TVIS document). So,
I thought it would be a good idea to raise the amount of water injected. So
far, it's running great - same boost, same outside temperature, no bad gas
mode.
It's possible that it went into bad gas mode when the water pressure was at
its lowest - that coupled with the low outside air temperature.
New Version 2.0 Water Injection!
The new version of my water injection setup uses the following components:
- Shurflow 100psi pump
- Shurflow accumulator
- 2 150psi Solenoid valves
- 2 pressure switches
- Water pressure gauge
- Mini mister nozzles from http://www.mcmaster.com
- Tank with level sensor from junk yard (Oldsmobile)
- LEDs to indicate pump on, solenoid 1 on, solenoid 2 on, and low water in tank
The Shurflow pump has an internal regulator set to 100psi. The
pump is therefore supplied with +12 volts at any time the ignition switch
is turned on. The two solenoids are controlled by the two pressure
switches T'd into the intake manifold (boost pressure). The solenoids
and pressure switches were purchased from http://www.poweraire.com. Total
cost for the setup was approximately $30 per solenoid, $40 for accumulator,
$80 for pump, $20 per pressure switch, $10 for the gauge from Lowes hardware,
$10.00 for the nozzles, $30 for various fittings, hose etc, and about
$15.00 for wiring, LEDs, fuse and so forth - so a total of ~$275.00 not
including shipping. The current nozzles are a 3 gallon per hour
(first solenoid) and a 5GPH (2nd solenoid) nozzle for a total of 8GPH
or 504cc/min at 100psi. The current tank can hold about
1 gallon of water, so the setup can support full boost for 6 minutes. The
pressure from the setup varies from 60psi (where the pump turns on) to
100psi (where the pump turns off). By using an accumulator, the
pump runs very infrequently. During 'normal' commuting of 50miles
a day, I see the pump come on about 2 times. It takes a good while
for the pressure to drop from 100psi down to 60 where the pump turns
on. Once the pump turns on, the pressure builds very quickly from
60psi to 100psi; about 2.5 seconds.
I'm currently running 19.2psi of boost with this setup, and the ECU seems happy
so far (no knock mode). Personal best 0-60MPH time is 4.8 seconds.
Future
Currently there is no more intercooler mister, as I wanted to keep the
hoses going from the solenoids to the throttle body nozzles as short as possible. By
keeping these lines short, there is minimal dripping after the solenoid closes. It
also ensures that when the solenoid opens, water will flow immediately. I'm
planning on adding an additional solenoid and nozzles to mist the intercooler
and possibly the front radiator under high boost conditions.
Current Measured Performance
My most recent run with the GTech performance meter shows 258HP running 19.2
psi.
More pictures on the MR2 picture page.
Old version 1.0 Water Injection
I've finished putting together and installing my own water injection
setup. It uses a pressure tank that contains a water bladder. The
tank is 2 gallons. I fill the water bladder with one gallon of
water, and then pressurize the tank with an air compressor to 100psi. The
setup uses two pressure switches to control two misting water nozzles
(mcmaster car mini-mister nozzles). The first nozzles comes on
at 5psi and sprays water onto the outside of the intercooler. The
second nozzle comes on at 10psi - currently using 189cc/min nozzle at
100psi, and injects right before the throttle plate. The pressurized
water is controlled via two solenoid valves. This allows the not
only a fail-safe for the throttle body injector (in case one solenoid
fails), but also permits the use of a second nozzle for the intercooler
mister.
Advantages:
No Pump - no pump delay - injection starts immediately.
Doubles as intercooler mister.
High pressure - excellent atomization (at 40-100psi).
Turn on pressure easily adjustable via adjustable switches.
Able to run with denatured alcohol.
Disadvantages:
Filling the tank is somewhat cumbersome, but not too bad. Have to drain
air out, open valve, and gravity feed the tank occasionally letting excess
air out. After filling - close the valve, and pressurize via air compressor. On
a two gallon tank, with one gallon water, and one gallon 100psi air, after
all water has been used, pressure will have dropped to 50psi. The user
can just re-pressurize the tank - but that leads to - Knowing how full the
tank is. I'm still working on this one - can use pressure reading to
see how full, but would be nice to use an additional pressure switch to turn
on an LED when the tank is empty.
Observations
Water injection really does work - I've noticed at least a 100
degree drop in EGTs, and I can run more boost without the ECU going
into the bad gas mode. This can be observed via two LEDs connected
to the turbo VSV, and the TVIS ports on the ECU. When the ECU
goes into the bad gas (knock) mode, it will open the TVIS valves under
any throttle position other than closed, and the ignition timing seems
to be severely retarded. Since I changed the headgasket (and
had the head resurfaced) the ECU has been going into this mode under
moderate (14.2psi) with PT upgraded 50 trim turbo - I believe this
is due to increased compression. I've been able to run 15.6 psi
with water injection without problems, and also tried 17.1psi briefly
without issues. I did some GTech runs with and without water
injection, and also with a 50/50 mixture of water and denatured alcohol
- results are averaged:
Just distilled water:
14.2 psi without 225
14.2psi with 222
15.6psi with water 242.
50/50 mixture of distilled water and denatured alcohol:
14.2psi - 225
15.6psi - 235
17.1psi - 242.
I attribute the lower numbers with the alcohol to the engine running too rich
- but that's just a guess.
I also did a my personal best 0-60MPH time with distilled water at 15.6psi
- 5.22seconds.
More pictures are on the pictures page.
Oh - BTW - the nozzle for the intercooler is 315cc/min. So one gallon
of water will last about 7.5minutes - course that would be under boost conditions
- with just the throttle body water injector it would last 20 minutes.
Great article about water injection from 1943 - some really interesting tests.
Any questions or comments - please email me at joelori@earthlink.net
