In keeping with the excellent integration with the Di engines, the latest HFS4-v3.1 is packed
with even more capabilities. 

An additional AUX input (0-5V) allows the system to alter flow based on air, exhaust temperature or air fuel ratio. If one of signals exceeds a pre-set level, failsafe will be triggered to protect your engine. The standard turbine flow sensor based failsafe remains.

A “Fast Acting Valve” (FAV) controls the delivery rate based on a PWM signal from the 

HF4 controller. The FAV enables superior linearity and atomization across the entire injec-
tion range. A constant line pressure (160 psi) is provided by an Aquatec pump working
in the “by-pass” mode. This method is very similar to the conventional fuel injection sys-
tems, allowing wide dynamic range and lighten responses to engine load.

The combination of quality components, superior method of delivery and a precision Di
signal decoding algorithm, the HFS4-v3 remains to be the most advanced and capable
water/methanol injection system in the world to date.

Lastly, we have oulined a capability and price comparison chart here against some popular brands. 

User manual: version3 (serial no. 121500 on)

User manual (April 2015 on): version3.1 (serial no. 121750 on)

User manual (April 2017 on): version3.12 (serial no. 122228 on)

 Choosing water/methanol flow for your application:

• 100% water:  10-15% water/fuel ratio or 0-5-1cc per BHP 
• M50/W50: 15-20% MW/fuel ratio or  1-1.5cc per BHP
• 100% methanol: 20-25% methanol/fuel ratio or 1.5-2cc per BHP 

Selecting the correct jet or jets for the required flow: 

• Calculate the "true" pressure by subtract the 160psi pump pressure by the "boost" pressure
• Select the jet or jets from "true" pressure from the chart below (compensated).
• Always pick the next size up or allow 10-15% more to allow more headroom.  

Notes on Direct Port application:

• Divide the final flow amongst the DP jets
• Allow one extra jet for IAT cooling, normally twice the size of the DP jet.  (re-calculate DP jet)
• Ideally the DP jet should have an external or internal check valve to minimise vacuum induced after-spray. 
• Insert an "high pressure inline filter" before the FAV to minmise the risk of clogging. 
• Order extra jet adaptors (806-357N) - Std. kit comes with two.
• Recommend using the aquamist Hex Manifold. (comes standard with all compression fittings)
• Optional PTFE (4mm) is optional but ideal for combating the heat in the engine compartment. Essential for track or rally events   
• Keep hose run to the DP jets as short as possible. Not necessarily need to be "equal" length.    
• Contact aquamist for your unique application before ordering.