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---- 806-065 ----- HFS4-v3.1 system for DI engines The most advanced system to date.

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Your Price:
USD909.97 (You save USD47.90)
4.40 KGS
Estimated Shipping Time:
*** 3-5 weeks *** (many apologies)
Calculated at checkout
* led colour:
Std. Jet sizes or select any 3:

(Maximum Size: . Type: )
Universal or Car model specific:
Estimated HP?:

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Product Description


** Please note the HFS4 supports all DI engines under the "universal" option


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: version3.1 (serial no. 121750 on)

User manual: 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.  




Other Details

Full kit without water tank.
Std. jets:
0.8, 0.9, 1.0mm (if not specified with order)
richard@aquamist.co.uk (purchased from here only)

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