The F5 Series

The Haltech F5 is a supplementary fuel injector computer designed to control the fuel delivery of an additional injector or injectors fitted to an engine’s fuel system as part of an after-market turbocharger or supercharger installation.

Without additional fuel delivery it is likely that the engine would ‘lean-out’ under higher boost pressures as a normally aspirated car’s fuel system is not designed to deliver additional fuel required once the engine is boosted.

The F5 System is totally independent of the standard fuel system. This makes it universal to most turbocharging or supercharging installations.

The F5 senses two engine parameters and actuates the supplementary injectors accordingly.

These parameters are:

Engine RPM:
   The rpm trigger is taken from the negative side of the ignition coil.
   For every 2 coil discharges the F5 computer actuates the supplementary fuel injector once.

   The fuel delivery is therefore tied to engine rpm.
   As the rpm doubles for constant load, the number of injector actuations doubles and so the additional fuel injected doubles.

Engine Load:
   The engine load is proportional to the amount of air/fuel drawn on each intake cycle
   which is turn proportional to the pressure in the inlet manifold.

   The F5 measures the pressure in the inlet manifold and therefore has feedback relating to
   engine load which it uses to increase the rate of delivery of fuel as the pressure increases.