Nissan 350Z Intercooled Twin Turbo kit >> AutoTech Engineering

High horsepower demands precise fuel delivery to each individual injector, particularly under demanding conditions such as drag racing and autocross.

The APS upgraded fuel system is a complete bolt-on precision fuel system that consists of a comprehensive range of components designed specifically to support huge horsepower and yet retain excellent fuel atomisation, fuel economy and driveability in day to day driving conditions.

The drop-in Quad Orifice Directional pattern injectors supplied in the APS Single or Twin Turbo Systems flow 500 cc at 4.0 Bar (58 psi) differential fuel pressure. Each of these injectors are ideal for sustaining 100 horsepower (flywheel) while maintaining a 12.0:1 air fuel ratio - for a total of an insane 600 horsepower at the flywheel.

Differential pressure is the critical yardstick when discussing injectors in forced induction applications. As boost pressure increases inside the inlet manifold where the injectors are situated (lower half of the intake manifold) the fuel rail pressure must also increase proportionally in order to maintain a constant pressure difference across the injector orifice. This is called a constant differential pressure fuel system.

Less sophisticated fuel systems may not employ a constant differential pressure fuel supply - instead they maintain a constant fuel rail pressure that does not increase with increasing boost pressure. These are called constant fuel pressure systems and were only ever designed for naturally aspirated applications.

The table below compares the pressure difference across a fuel injector orifice at different boost pressures for both constant fuel pressure and constant differential pressure fuel systems.

Boost pressure	Constant Fuel Pressure		APS Constant Differential Pressure
Boost pressure	Fuel Rail Pressure	Injector Orifice Pressure Difference	Fuel Rail Pressure	Injector Orifice Pressure Difference
0 psi	58 psi	58 psi	58 psi	58 psi
2 psi	58 psi	56 psi	60 psi	58 psi
4 psi	58 psi	54 psi	62 psi	58 psi
6 psi	58 psi	52 psi	64 psi	58 psi
8 psi	58 psi	50 psi	66 psi	58 psi
10 psi	58 psi	48 psi	68 psi	58 psi

As can be seen from the table above, with a constant fuel pressure system, the pressure difference across the injector orifice drops as the boost pressure increases - and consequently the volume of fuel supplied by the injector drops as well. This can lead to engine damage through lean mixtures at moderate to high boost pressure levels. The APS system addresses this issue and is a true constant differential pressure fuel system that maintains a constant pressure difference across the injector orifice.

An advanced injector wiring loom is also included in the APS upgraded fuel system in order to avoid cutting and soldering of the original injector looms. After all, a bullet proof electrical connection is vital for injectors on a high performance engine such as the single or twin turbo Z.

This wiring loom is unique to the industry of forced induction packages to suit the 350Z and follows the strict APS philosophy of designing and manufacturing complete systems - that are truly complete.

High capacity injectors place extraordinary loads upon the fuel supply system and in the case of a high horsepower turbocharged 350Z, far higher capacity than the stock fuel pump can satisfy.

APS has produced the ultimate with an in-tank mount direct replacement fuel pump that will supply up to 600 horsepower (flywheel) at 4.5 Bar fuel pressure at 13.5 Volts. This is the operating fuel pressure when the APS Twin Turbo System intake manifold pressure sensing 4.0 Bar regulator registers 0.5 Bar (7.3 psig) boost pressure.

In order to ensure precise fuel pressure delivery at high horsepower levels, a 4.0 Bar fuel pressure regulator replaces the stock 3.5 Bar unit. In addition the APS fuel pressure regulator is vacuum/pressure referenced to the engine's intake manifold, therefore the regulator is mounted on the outside of the stock fuel pump/sender unit - and housed in a custom high flow housing assembly. In this way, fuel pressure across each injector orifice is maintained at a constant level regardless of the turbocharger boost pressure level - a configuration as found in the world's best turbocharged high performance production engines. Best of all, the restriction caused by the stock 3.5 Bar regulator is removed completely and a new custom replacement plug is included to facilitate this.

The APS custom high flow regulator housing is safely bracketed on the top of the stock fuel pump/sender unit and therefore no cutting of the stock sheet metal is required. New high pressure fuel line, custom made high flow hose barbs and the correct style hose clamps complete this beautiful installation.

In order to facilitate the fuel return from the external regulator housing, a single 12.0 mm hole is drilled in the top flange of the plastic sender unit. In order to deliver a perfect seal and return the fuel to the correct section of the pump housing, a custom configured fuel return pipe is also supplied. This is professionally flanged, Viton O-ring sealed and locked into position with a special lock-nut and washer arrangement.

This complete and comprehensive fuel upgrade system is a part of the APS Single or Twin turbo systems.

The APS fuel system by far exceeds any fuel system found in other brands of Turbo systems for the 350Z and addresses the erratic fuel pressure problems associated with non-return fuel systems that utilize a high capacity pump and upgraded fuel pressure regulator - in fact, the APS fuel system stands head and shoulders above the rest! A total package engineered for extreme performance in line with the APS philosophy of total system engineering.

To see more components for the Nissan 360Z Twin Turbo kit click HERE