All LS1 / LS6 motors (except 97-98 Corvettes) use a returnless
type fuel system operating @ 58 psi. The BMW has a return type
fuel return system operating @ 43 psi with a pump flow rate of 90
To make the LS1 work with the BMW the operating pressure
needs to be increased, the pump volume needs to be increased to
a minimum of 130 L/hr, and either the LS1 needs to be converted
to a return type system or the BMW needs to be converted to a
returnless type system.
The LS1 can be converted to a return type system by replacing
the fuel rail with a ‘97 or ‘98 Corvette fuel rail. I elected to
convert the BMW to a semi returnless system by adding a
pressure regulator in line and using the BMW return line as show
in the following diagram. I used the stock fcar regulator that I
scavenged out of the fuel pump assembly that came with the
motor package. A better option is to use an aftermarket
adjustable regulator so that the F/A ratio can be optimized.
Getting enough fuel volume will be accomplished by installing the
stock fcar fuel pump onto the BMW in-tank bracket. If this proves
to be a difficult cobble job then option 2 is to install an external
inline pump and replace the in-tank pump with a pickup hose.
Another more expensive option would be to replace the in-tank
pump with an M3 pump.