Fueling for Boost
Upgrading the fueling system for our G37 ended up being more complicated than we expected. For lower power forced induction projects, bigger injectors and a higher capacity fuel pump may be most of what’s needed for fueling. When we considered fueling the VQ37VHR for boost we didn’t want to have to come back later for upgrades. We also didn’t want the fueling to be a potential weak point in our build and we’ll address those points here. A future article will detail the fueling system installation. Follow these links to read about our Vortech V3 SI supercharger or our Infiniti G37S project.
One company kept bubbling to the top when needing a fueling solution for the 370z and G37 and that’s CJ Motorsports. They offer a range of products that go beyond fueling for these cars. There are a few parts like their oil rail that would vastly simplify the mess of adapters we used for our Autometer oil temperature gauge. Charles at CJ Motorsports was instrumental in stepping us through the process of selecting our fueling components. The first step was determining whether we had a G37 that had legacy G35 fueling components or if we had a car with newer 370z/G37 style components. This required removing the fuel pump module from inside the gas tank and determining which one of the two possible units our car was assembled with. Our car came with the newer 370z fueling system so we were able to select the right fueling system to proceed.
Taking a step back to take a step forward
We’re going to be installing the CJ Motorsports S1.SE fueling system that converts the stock returnless fuel system to a return fuel system. If like me you were wondering why a return system is necessary; it’s because fuel pressure to the factory fuel rails is about 52 psi minus any pressure drop along the plumbing. The fuel pressure in the factory system decreases as the flow increases. These pressure changes can be dealt with in tuning to a point but when considering adding 150 or more horsepower, a thorough redesign was necessary.
The CJ Motorsports S1.SE fueling system eliminates the stock fuel filter located in the fuel pump housing and the pressure regulator. Larger fuel feed lines are used to reduce pressure drop and keep the fuel pump on the higher end of its flow chart. An external fuel filter is added for serviceability and eliminating the stock fuel filter in the pump housing allows provisioning for larger fuel pumps. The fuel pressure regulator is relocated to the engine bay and regulates the fuel pressure after the line pressure drops so the fuel pressure stays where the regulator intends until the fuel pump can no longer keep up. On boosted VQ37’s fuel pressure can drop to as low as 15 psi and this new return system goes a long way in preventing that pressure drop from the 52 psi setting.