Increasing Fuel Pressure
Fuel pressure obviously plays a major role in the performance of your Electronic Fuel Injection system. Multi-port injection systems require much higher fuel pressure than mechanical systems can supply and the pressure and volume must be consistent throughout the entire rpm range of your engine. To answer these needs, MSD offers a high-output Electric Fuel Pump and Adjustable Regulators.
MSD Competition Fuel Injectors are flow rated at 43.5 psi (3 bar), but they will also perform and flow more fuel, with higher fuel system pressure. Increasing the fuel pressure also better atomizes the injector's fuel spray and improves its uniformity. So if you make slight changes to your engine combination you may be able to compensate without having to replace all of the injectors by increasing the fuel pressure. But how high can the pressure go?
It is recommended that the fuel system pressure does not exceed 72.5 psi (5 bar) and that the specified injector electronic drivers are always used. To illustrate this increased flow capacity, here are the results of pulsed fuel testing of the largest MSD Injectors, PN 2014 (72 lb/hr) and PN 2015 (96 lb/hr). Both injectors were operated with their specified electronic driver at an 85% duty cycle (equaling 10.4ms on-time).
Note: The MSD Adjustable Pressure Regulators are useful for setting fuel pressure at 5000 rpm and fuel specific gravity was 0.788. Wide open, non-pulsed static) flow would of course be higher, but this data is more accurate for real world use with an engine management system.
Fuel Pressure |
PN 2014 (72 lb/hr) |
PN 2015 (96 lb/hr) |
30 |
60 |
78 |
40 |
69 |
91 |
50 |
77 |
100 |
60 |
82 |
109 |
If you know an injector's static (non-pulsed) fuel flow at one system pressure you can derive its static flow at another pressure with this equation.
*@ 10.4 milliseconds
F2 is the calculated injector static flow (lb/hr) at the higher pressure.
P2 is the fuel system pressure (psi) you want to use.
P1 is the fuel system pressure (psi) the injector is rated for.
F1 is the injector's static flow (lb/hr) at its rated fuel system pressure in psi.
For example, our PN 2018 injector is static flow rated at 38 lb/hr at 43.5 psi. If we want to know what its static flow will be at 60 psi then:
Following are two conversions tables to assist your calculations:
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