Haltech E6K - Manual (Page 129)

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APPENDIX D FUEL SYSTEMS & STAGING
The best EFI installation will yield poor results if the fuel system does not meet the demands
of the engine. Insufficient fuel flow can lead to engine lean out and detonation which could
cause serious damage. For the safety of your engine, we urge you to check your fuel system's
capacity and ensure that there will be sufficient supply at all times. A fuel pressure meter
should be used during testing and tuning to ensure that fuel pressure does not fall out of
regulation i.e. that the pressure does not drop or oscillate.
This appendix offers guidelines to testing your fuel system and suggests some solutions if
there are supply problems. If you find you need to modify your fuel system and are unsure
what to do, contact a Haltech dealer for advice.
WARNING:
FUEL IS DANGEROUS. BEWARE OF FLAMES, CIGARETTES,
ELECTRICAL SPARKS, ETC.
D.1 Fuel Requirement
If you can estimate the power output of a gasoline engine, you can make a reasonable guess at
the fuel flow requirement. A simple rule of thumb, thus, may be expressed in metric or
imperial units.
Note: Every 100 hp needs around 50 lb/hr (8.0 US gal/hr) of fuel
(6.6 Imp gal/hr)
Every 100 kW needs around 670 cc/min (40 L/hr) of fuel
This assumes a brake specific fuel consumption of 0.50. The actual fuel flow necessary by
injectors and pump are likely to exceed a figure derived this way. This is due to the overheads
in injector dead time and pumping return fuel to maintain regulation.
D.2 Injector Flow Capacity
If you have purchased second hand injectors, or have removed the current injectors while
doing work on the engine, we strongly recommend that you clean and flow test them. If you
have bought new injectors, it is worth flow testing them anyway if you do not know their flow
rate. Make sure that you test the injectors at the fuel pressure that your regulator is operating.
Your total injector flow capability is given by the sum of the injector flow rates. Injector flow
rates are usually specified in either cc/min or lb/hr. Check that you have enough injector flow
to match the estimated power output comfortably. Keep in mind that you do not want to
exceed 85% duty cycle injection on time, and that at high rpm, injector dead time can
consume a significant amount of available injection time.
If you find that your injector flow is insufficient, you can change to larger injectors, add extra
injectors, or increase fuel pressure. Raising fuel pressure to increase injector flow rate is not