Scott
I have finally transferred your great write-up:
Water injection Study Models
This is a brief but concise documentation of the following water injection study carried out in March 06.
First of all let me explain why I decided to do the experiment.
After reading various forums and trying water injection within a controlled environment (A regional drag strip), I decided the best way to cut through some of the rumours, myths and facts surrounding various mixtures, and possible gains and losses associated with those mixtures.
From information gained on the Internet the general feeling was that injecting water or other chemicals into the intake tract would/could un-harness possible power gains for very little effort.
I used my own car for these tests, Mazda RX-7 FD3S twin turbo. The car itself is highly modified so was a stable platform from which to launch the test.
The data was captured using FC Datalogit software and analysed using Data log lab.
The water injection was the new Coolingmist vari-cool controller operating a multi nozzle system, one nozzle being at the throttle body and the other being just after the intercooler.
The tests were performed using the same fuel map and ignition maps on the same stretch of track, minutes apart. The fueling was set at 11:1 at peak torque which was considered safe for this tune at a boost level of 14.7 psi with a safe level of ignition advance.
The above power graph is the control for the test. 11:1 AFR @ 14.7 psi at peak tq. Air temps were 34 deg C at stand still dropping to 30 deg at 7000 RPM, peak knock was 33 @ 6000 RPM.
The above power graph is for water injection. Max flow was at full boost of 14.7 psi and was 4 GPH of water. The AFR?s seemed to be a touch richer on this run dipping from 11:1 to 10.8:1 in most of the full boost cells of the fuel map log (this seemed very odd with water not being a fuel and also displacing air). Air temps were a bit cooler at stand still 25 ?C and had a reduction at 6000 rpm to 19? (a drop of 6 ?C in a matter of seconds). Max knock was 33 at 6800 RPM
This power graph is 50:50 Methanol: Water. The flow rate was the same as the previous run.The AFR?s were again a touch richer than the control dipping to 10.5:1 in a high RPM cell but were generally between 11:1 and 10.8:1. The AFR?s do seem to be a little unstable with this mixture as compared to other runs. Air temps were back up again for this run to 31 deg standing and dropped to 27 deg at 6700 RPM. The knock peaked to 32 @ 6000 RPM.
This power graph is for Methanol. The flow rate is the same as the previous runs. The AFR?s were very rich on this run, which makes sense. A very cool 10.3:1 at its richest and barely coming out of the 10:1 range at all.
Air temp @ standstill was 28 ?C and dropped to 26 ?C as soon as the system started to run but lowered no further than this. Knock peaked at 31 at 4000 RPM but as a whole was extremely low whilst on boost.
The above table is a simple representation of the results from the runs. The results run in number order. Ie 1 being the best & 4 being the worst. I have highlighted the best as blue and the worst as red.
Methanol is the best overall mix in this test. But 50:50 mix seems to be superior.
N.B please note all of these results are on a untuned basis. There is still plenty of room for additional tuning and power gains over this tune. Once tuning has take place different mixtures may well take over as the top mixture. I predict there is around 50 hp more in most tunes. The hp figures were kept low intentionally to keep the tune safe due to other mixtures that were used in this test but not displayed in this document.
In brief different mixtures and chemicals will give different results. The data above is just the tip of the iceberg as far a tuning these chemicals goes. This data clearly shows that there is a very small margin for real performance gains without proper tuning, but also shows that a bit more safety can be achieved with a bit of thought into the mix.
I hope this info is useful and helps clear up some myths concerning this subject
Scott Bishop