Kinsler_Handbook_#32 December 2017

Kinsler Fuel Injection, Inc, 1834 THUNDERBIRD TROY, MICHIGAN 48084 U.S.A. Phone (248) 362-1145 Fax (248) 362-1032 154 EFI PLUMBING FILTRATION Pleated 10-micron paper filter elements ( see FUEL FILTERS on Pages #162-166) in this system are very fine, so they do an excel- lent job of cleaning the fuel, but this means they plug up quickly. Replace them after about every twenty hours of racing when operating on gasoline or every race event when using methanol. It is an excellent idea to use one of our large 45 micron filters to filter the fuel when filling the main tank. This will greatly extend the life of the elements in the system. Be extremely careful to keep water out of the tank as it swells the paper elements shut. SYSTEM PRESSURE We prefer to operate our EFI systems at about 70 PSI rather than the typical 45 PSI, as we find slightly better power and economy and less sensitivity to pressure fluctuations. A 1 PSI fluctuation affects a 45 PSI system more than a 70 PSI system: see ORIFICE THEORY on Pages #202-203. Sometimes system cost prohibts running the higher pressures. Fuel pressure reading should be taken as close as possible to the center of the fuel rail. This provides an average pressure reading. If the pressure gauge is installed before filters, tees, etc., the pressure gauge will read higher pressure than there really is in the rails, due to the pressure drop across these components. FUEL RAIL BASICS We recommend that EFI injectors be plumbed using fuel rails, rather than individual hoses. The instantaneous opening and closing of the injectors causes large pressure pulses in the system. This pulsing can be dampened by common fuel plenums (rails), a high quality pressure relief valve, and/ or a specially designed damper (see Page #143). Pressure spikes can cause poor fuel distribution and in severe cases lean conditions which can damage the engine. Two types of fuel rail material : 1) Aluminum - low cost and easy to machine. 2) Stainless steel - for use with alcohol and nitro. See EFI FUEL RAILS on Pages #141-143 and TOOLING TO MACHINE FUEL RAILS AND INJECTOR MOUNTING on Page #144. PLUMBING OF EFI SYSTEM WITH ELECTRIC FUEL PUMP ONLY VACUUM/BOOST REFERENCE The pressure relief valve should be referenced to vacuum and/ or boost. This will help offset the manifold absolute pressure on the outlet of the injector to maintain a constant injector flow rate (see EFI PRESSURE RELIEF VALVES AND ACCESSORIES on Pages #134-135, Fig. 2). TYPES OF FUEL RAIL PLUMBING PARALLEL : Parallel plumbing is done by teeing the feed hose from the pump into both fuel rails, then connecting the two outlets to the pressure relief valve, see Fig 1. This gives twice the flow capacity of series plumbing. It also reduces the fuel velocity in the rail when compared to series plumbing. If the fuel velocity is too high it may cause flow disturbance in the fuel rails. A parallel configuration is recommended to achieve the best cylinder to cylinder distribution. SERIES : Series plumbing is done by feeding fuel into one rail, then out to the other rail, then to the pressure relief valve, see Fig. 2. This configuration has inherent fuel supply problems for the last cylinders in the series. This is most apparent on a Group Fire type of EFI system since the injectors are fired in groups of 4 or 8 (on a V8 engine) causing a high demand in an instantaneous period of time. This plumbing method is NOT recommended on high horsepower engines. © 2017 SERIES PLUMBING Fig. 2 PARALLEL PLUMBING Fig. 1