AEM Performance Electronics 30-3300 - Engine Tuning; Tuning for Power Gain; AFR and Flow Rate Adjustment; Cold Weather Operation

Water/Methanol Injection V2
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© 2020 AEM Performance Electronics
ENGINE TUNING
Water/methanol injection is generally not considered a bolt-on power adder for forced induction gasoline
applications. Engine tuning is usually required in order to maximize potential power gain. Water/methanol
injection allows for a more aggressive tune to be used while still using pump gas as your base fuel.
Using a 50/50 mix of water/methanol is recommended for the best combination of air charge cooling and
detonation control. With conservative boost and timing, establish a base AFR that is one point higher than your
final target AFR. For example, if your final target AFR with water/methanol injection is 11.0:1, set your base AFR
to 12.0:1. Once the base AFR has been set, start injecting water/methanol and adjust the injection flow rate to
achieve your final target AFR. For example, if before injection your base AFR is 12.0:1 and then during injection
your AFR drops to 10.5:1, reduce the water/methanol flow rate until your final target AFR is reached. It is
generally recommended that the flow rate of the injection system be changed in order to reach your target AFR
and NOT your primary fueling. Injection flow rate adjustments can be made by changing your nozzle selection
or by adjusting the “Start PSI” and “Full PSI” settings.
Once the injection flow rate is set to deliver your desired final AFR, boost and ignition timing can be increased to
take advantage of the additional air charge cooling and detonation control. When injecting the correct amount, a
50/50 mix of water/methanol has been shown to provide an effective octane of over 110 when using a base fuel
of 91–93 octane pump gas. A properly tuned water/methanol injection system will usually support a typical “race
gas” engine tune.
COLD WEATHER OPERATION
A water/methanol mix will also lower the freezing point of the fluid. Below is a chart with freezing points for
different percentages of water/methanol mixtures.
Temperature
Methanol Concentration % by
Volume
20
o
F
13
0
o
F
24
-15
o
F
35
-40
o
F
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MAINTENANCE
The injector nozzle should be cleaned periodically. Disassemble the nozzle and clean it with a suitable cleaner
until all debris is removed. If excessive contamination is found, check the rest of the system for the source.