AEM 30-71XX Infinity Stand-Alone Programmable Engine Mangement System Full Manual - Manual (Page 311)

Fuel System Setup 305
© 2014 AEM Performance Electronics
Fuel Pump
To achieve proper fuel delivery, you must select the right fuel pump for your vehicle. In most
cases, where the engine has been modified only with “bolt on” performance items, there is rarely
need for a larger fuel pump or larger injectors. Vehicle manufacturers typically design a “safety
factor” into the fuel pump to accommodate the deterioration of the fuel system over time. This
safety factor is intended to compensate for a fuel filter that is nearing the end its life, or for
deposits in the injector orifice. Our research has revealed that generally there is about a 15%–
20% oversize in most factory fuel pumps.
If the engine is enhanced via forced induction or nitrous oxide, the stock fuel pump is
inadequate. If the engine’s power is increased more than 15–20% fuel delivery must
increase as a factor of the power gain.
The way to determine the proper-size fuel pump is based on the desired brake specific fuel
consumption (BSFC) of the engine. This term refers to how much fuel in pounds per hour (pph)
the engine consumes per horsepower and is a measure of the efficiency of the engine. It is a
useful term in determining the total fuel requirement of the engine. On vehicles equipped with
forced induction or nitrous oxide, higher BSFCs are required as an added measure of safety to
prevent detonation or high combustion chamber temperatures. Below is a guide of BSFCs with
standard CR that AEM uses for various engines that run on gasoline:
Naturally Aspirated engines have a BSFC of .48 to .50.
Forced Induction engines have a BSFC of .65 to .68.